博客第二次作业
目录:
（1）前言
（2）设计与分析
（3）改进建议
（4）总结
前言:
（1）关于接触了java之后一段时间的感想
java学习至今其实已经是对编程的习惯造成了很大的影响，原先一直是觉得java面向对象的语言是一种很麻烦的的事情，明明面向过程的C语言已经足够了，为什么还要搞一个面向对象的java语言呢，现在可以给一个答案，因为方便，因为积累，因为”继承“。继承真的赋予了java语言很大的灵活性，在之后的这些练习中也很好的进行了夯实基础及提升
（2）设计与分析：
今天主要对以下四个题目进行分析分别是：PTA题目集4（四边形）、5（五边形）以及期中考试
PTA题目集4(四边形)：
1 import java.text.DecimalFormat; 2 import java.util.Scanner; 3 import java.util.regex.Matcher; 4 import java.util.regex.Pattern; 5 public class Fours { 6 public static void main(String[] args) { 7 try (Scanner input = new Scanner(System.in)) { 8 int t[] = { 0, 8, 8, 8, 12, 10 }; 9 String str = input.nextLine(); 10 String[] arr = str.split("[: ,]"); 11 double[] num = new double[12]; 12 int max = 0; 13 int choice = -1; 14 15 String content = str; 16 if (str.charAt(1) != ':') { 17 System.out.println("Wrong Format"); 18 System.exit(0); 19 } 20 String regStr = "[:, ]+"; 21 Pattern pattern = Pattern.compile(regStr); 22 Matcher matcher = pattern.matcher(content); 23 String ss = ""; 24 while (matcher.find()) { 25 ss = ss + matcher.group(0); 26 } 27 if (ss.charAt(0) != ':') { 28 System.out.println("Wrong Format"); 29 System.exit(0); 30 } 31 for (int i = 1; i < ss.length(); i++) { 32 if (i % 2 == 1) { 33 if (ss.charAt(i) == ',') { 34 continue; 35 } else { 36 System.out.println("Wrong Format"); 37 System.exit(0); 38 } 39 } else { 40 if (ss.charAt(i) == ' ') { 41 continue; 42 } else { 43 System.out.println("Wrong Format"); 44 System.exit(0); 45 } 46 } 47 } 48 49 if (arr[0] == "") { 50 System.out.println("Wrong Format"); 51 System.exit(0); 52 } else { 53 if (judge(arr[0])) { 54 if (arr[0].charAt(0) < '1' || arr[0].charAt(0) > '5') {// 6.0 55 choice = 0; 56 } else { 57 if (arr[0].length() == 1) { 58 choice = Integer.parseInt(arr[0]); 59 } else { 60 choice = 0; 61 } 62 } 63 } else { 64 System.out.println("Wrong Format"); 65 System.exit(0); 66 } 67 } 68 if (choice > 5 || choice < 1) { 69 System.out.println("Wrong Format"); 70 System.exit(0); 71 } 72 for (int i = 1; i < arr.length; i++) { 73 if (max >= t[choice]) { 74 System.out.println("wrong number of points"); 75 System.exit(0); 76 } 77 if (judge(arr[i])) { 78 num[max++] = Double.parseDouble(arr[i]); 79 } else { 80 System.out.println("Wrong Format"); 81 System.exit(0); 82 } 83 } 84 if (max != t[choice]) { 85 System.out.println("wrong number of points"); 86 System.exit(0); 87 } 88 89 switch (choice) { 90 case 1: 91 judgequadrilateral(num, num[0], num[1], num[2], num[3], num[4], num[5], num[6], num[7]); 92 break; 93 case 2: 94 judgespecialqua(num, num[0], num[1], num[2], num[3], num[4], num[5], num[6], num[7]); 95 break; 96 case 3: 97 jdugequas(num, num[0], num[1], num[2], num[3], num[4], num[5], num[6], num[7]); 98 break; 99 case 4: 100 getans(num, num[0], num[1], num[2], num[3], num[4], num[5], num[6], num[7], 101 num[8], num[9], num[10], num[11]); 102 break; 103 case 5: 104 judgein(num, num[0], num[1], num[2], num[3], num[4], num[5], num[6], num[7], num[8], num[9]); 105 break; 106 default: 107 System.out.println("Wrong Format"); 108 } 109 } 110 } 111 112 public static void getans(double num[], double x1, double y1, double x2, double y2, double x3, double y3, 113 double x4, double y4, double x5, double y5, double x6, double y6) { 114 System.out.println("not a quadrilateral or triangle"); 115 } 116 public static void judgein(double num[], double x1, double y1, double x2, double y2, double x3, double y3, 117 double x4, double y4, double x5, double y5) { 118 119 if (quadrilateral(num, x5, y5, x2, y2, x3, y3, x4, y4)) { 120 for (int i = 2; i < 10; i += 2) { 121 if (num[0] == num[i]) { 122 if (num[1] == num[i + 1]) { 123 System.out.println("on the quadrilateral"); 124 System.exit(0); 125 } 126 } 127 } 128 if (gett(num, x1, y1, x2, y2, x3, y3, x4, y4).equals("on") 129 && gett(num, x1, y1, x2, y2, x4, y4, x5, y5).equals("on")) { 130 System.out.println("on the quadrilateral"); 131 } else if (gett(num, x1, y1, x2, y2, x3, y3, x4, y4).equals("on") 132 || gett(num, x1, y1, x2, y2, x4, y4, x5, y5).equals("on")) { 133 System.out.println("on the quadrilateral"); 134 } else if (gett(num, x1, y1, x2, y2, x3, y3, x4, y4).equals("in") 135 || gett(num, x1, y1, x2, y2, x4, y4, x5, y5).equals("in")) { 136 System.out.println("in the quadrilateral"); 137 } else { 138 System.out.println("outof the quadrilateral"); 139 } 140 141 } else { 142 boolean st[] = new boolean[10]; 143 double x[] = new double[3]; 144 double y[] = new double[3]; 145 int cnt = 0; 146 for (int i = 2; i < 10; i += 2) { 147 for (int j = i + 2; j < 10; j += 2) { 148 if (num[i] == num[j] && !st[i] && !st[j]) { 149 if (num[i + 1] == num[j + 1]) { 150 cnt++; 151 st[j] = true; 152 } 153 } 154 } 155 } 156 if (cnt >= 2) { 157 System.out.println("not a quadrilateral or triangle"); 158 } else { 159 int ttt = 0; 160 for (int i = 2; i < 10; i += 2) { 161 if (!st[i]) { 162 x[ttt++] = num[i]; 163 y[ttt++] = num[i + 1]; 164 } 165 } 166 if (judgesanjiao(x[0], y[0], x[1], y[1], x[2], y[2])) { 167 String sss = gett(num, x1, y1, x[0], y[0], x[1], y[1], x[2], y[2]); 168 if (sss.equals("on")) { 169 System.out.println("on the triangle"); 170 } else if (sss.equals("in")) { 171 System.out.println("in the triangle"); 172 } else { 173 System.out.println("outof the triangle"); 174 } 175 } else { 176 System.out.println("not a quadrilateral or triangle"); 177 } 178 } 179 } 180 } 181 182 public static boolean judgesanjiao(double x1, double y1, double x2, double y2, double x3, double y3) { 183 double l1 = Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2)); 184 double l2 = Math.sqrt(Math.pow(x2 - x3, 2) + Math.pow(y2 - y3, 2)); 185 double l3 = Math.sqrt(Math.pow(x3 - x1, 2) + Math.pow(y3 - y1, 2)); 186 if (l1 > l3) { 187 double t = l1; 188 l1 = l3; 189 l3 = t; 190 } 191 if (l2 > l3) { 192 double t = l2; 193 l2 = l3; 194 l3 = t; 195 } 196 if ((l1 + l2 - l3) <= 1e-6) { 197 return false; 198 } else { 199 return true; 200 } 201 } 202 203 public static String gett(double num[], double x4, double y4, double x1, double y1, double x2, double y2, double x3, 204 double y3) { 205 for (int j = 2; j < 8; j += 2) { 206 if (num[0] == num[j]) { 207 if (num[1] == num[j + 1]) { 208 return "on"; 209 } 210 } 211 } 212 double x[] = new double[3]; 213 double y[] = new double[3]; 214 String s[] = new String[3]; 215 s[0] = getPoints(x4, y4, x1, y1, x2, y2, x3, y3); 216 s[1] = getPoints(x4, y4, x2, y2, x1, y1, x3, y3); 217 s[2] = getPoints(x4, y4, x3, y3, x1, y1, x2, y2); 218 for (int i = 0; i < 3; i++) { 219 if (s[i] == null) { 220 return "out"; 221 } 222 } 223 for (int i = 0; i < 3; i++) { 224 String arr[] = s[i].split("[ ]"); 225 x[i] = Double.parseDouble(arr[0]); 226 y[i] = Double.parseDouble(arr[1]); 227 } 228 for (int i = 0; i < 3; i++) { 229 if (x[i] == x4) { 230 if (y[i] == y4) { 231 return "on"; 232 } 233 } 234 } 235 if (x[0] < Math.min(x2, x3) || x[0] > Math.max(x2, x3)) { 236 return "out"; 237 } 238 if (x[1] < Math.min(x1, x3) || x[1] > Math.max(x1, x3)) { 239 return "out"; 240 } 241 if (x[2] < Math.min(x1, x2) || x[2] > Math.max(x1, x2)) { 242 return "out"; 243 } 244 return "in"; 245 } 246 247 static void jdugequas(double num[], double x1, double y1, double x2, double y2, double x3, double y3, 248 double x4, double y4) { 249 DecimalFormat df = new DecimalFormat("0.0##"); 250 if (quadrilateral(num, x1, y1, x2, y2, x3, y3, x4, y4)) { 251 if (ut(num, x1, y1, x2, y2, x3, y3, x4, y4)) { 252 System.out.println("true " + df.format(getc(x1, y1, x2, y2, x3, y3, x4, y4)) + " " 253 + df.format(getmianji(num, x1, y1, x2, y2, x3, y3, x4, y4))); 254 } else { 255 System.out.println("false " + df.format(getc(x1, y1, x2, y2, x3, y3, x4, y4)) + " " 256 + df.format(getmianji(num, x1, y1, x2, y2, x3, y3, x4, y4))); 257 } 258 } else { 259 System.out.println("not a quadrilateral"); 260 } 261 } 262 263 public static double getmianji(double num[], double x1, double y1, double x2, double y2, double x3, double y3, 264 double x4, double y4) { 265 double a = geTsq(x1, y1, x2, y2, x3, y3); 266 double c = geTsq(x1, y1, x4, y4, x3, y3); 267 double b = geTsq(x4, y4, x2, y2, x3, y3); 268 double d = geTsq(x1, y1, x4, y4, x2, y2); 269 if (Math.abs(a + c - b - d) < 1e-6) { 270 return a + c; 271 } else { 272 return Math.min(a + c, b + d); 273 } 274 } 275 276 public static boolean ut(double num[], double x1, double y1, double x2, double y2, double x3, double y3, 277 double x4, double y4) { 278 double a = geTsq(x1, y1, x2, y2, x3, y3); 279 double c = geTsq(x1, y1, x4, y4, x3, y3); 280 double b = geTsq(x4, y4, x2, y2, x3, y3); 281 double d = geTsq(x1, y1, x4, y4, x2, y2); 282 if (Math.abs(a + c - b - d) < 1e-6) { 283 return true; 284 } else { 285 return false; 286 } 287 } 288 289 public static void judgespecialqua(double num[], double x1, double y1, double x2, double y2, double x3, double y3, 290 double x4, double y4) { 291 if (quadrilateral(num, x1, y1, x2, y2, x3, y3, x4, y4)) { 292 if (parallel(x1, y1, x2, y2, x3, y3, x4, y4)) { 293 if (linxin(x1, y1, x2, y2, x3, y3)) { 294 if (ve(x1, y1, x2, y2, x2, y2, x3, y3)) { 295 System.out.println("true true true"); 296 } else { 297 System.out.println("true false false"); 298 } 299 } else { 300 if (ve(x1, y1, x2, y2, x2, y2, x3, y3)) { 301 System.out.println("false true false"); 302 } else { 303 System.out.println("false false false"); 304 } 305 } 306 } else { 307 System.out.println("false false false"); 308 } 309 } else { 310 System.out.println("not a quadrilateral"); 311 } 312 } 313 314 public static double geTsq(double x1, double y1, double x2, double y2, double x3, double y3) { 315 double l1 = Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2)); 316 double l2 = Math.sqrt(Math.pow(x2 - x3, 2) + Math.pow(y2 - y3, 2)); 317 double l3 = Math.sqrt(Math.pow(x3 - x1, 2) + Math.pow(y3 - y1, 2)); 318 double c = l1 + l2 + l3; 319 double t = c / 2; 320 double s = Math.sqrt(t * (t - l1) * (t - l2) * (t - l3)); 321 return s; 322 } 323 324 public static double getc(double x1, double y1, double x2, double y2, double x3, double y3, 325 double x4, 326 double y4) { 327 double l1 = Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2)); 328 double l2 = Math.sqrt(Math.pow(x2 - x3, 2) + Math.pow(y2 - y3, 2)); 329 double l3 = Math.sqrt(Math.pow(x3 - x4, 2) + Math.pow(y3 - y4, 2)); 330 double l4 = Math.sqrt(Math.pow(x4 - x1, 2) + Math.pow(y4 - y1, 2)); 331 return (l1 + l2 + l3 + l4); 332 } 333 334 public static boolean ve(double x1, double y1, double x2, double y2, double x3, double y3, 335 double x4, 336 double y4) { 337 double a1 = x1 - x2; 338 double b1 = y1 - y2; 339 double a2 = x3 - x4; 340 double b2 = y3 - y4; 341 if (Math.abs(a1 * a2 - b1 * b2) < 1e-6) { 342 return true; 343 } else { 344 return false; 345 } 346 } 347 348 public static boolean linxin(double x1, double y1, double x2, double y2, double x3, double y3) { 349 double a = Math.pow(x1 - x2, 2) + Math.pow(y1 - y2, 2); 350 double b = Math.pow(x3 - x2, 2) + Math.pow(y3 - y2, 2); 351 if (Math.abs(a - b) < 1e-6) { 352 return true; 353 } else { 354 return false; 355 } 356 } 357 358 public static void judgequadrilateral(double num[], double x1, double y1, double x2, double y2, double x3, 359 double y3, double x4, double y4) { 360 if (coinCide(num, 8)) { 361 System.out.println("points coincide"); 362 } else { 363 if (quadrilateral(num, x1, y1, x2, y2, x3, y3, x4, y4)) { 364 if (Parallelogram(num, x1, y1, x2, y2, x3, y3, x4, y4)) { 365 System.out.println("true true"); 366 } else { 367 System.out.println("truefalse"); 368 } 369 } else { 370 System.out.println("falsefalse"); 371 } 372 } 373 } 374 375 public static boolean quadrilateral(double num[], double x1, double y1, double x2, double y2, double x3, double y3, 376 double x4, 377 double y4) { 378 if (parallel(x1, y1, x2, y2, x2, y2, x3, y3)) { 379 return false; 380 } else if (parallel(x2, y2, x3, y3, x3, y3, x4, y4)) { 381 return false; 382 } else if (parallel(x1, y1, x4, y4, x4, y4, x3, y3)) { 383 return false; 384 } else { 385 return true; 386 } 387 } 388 389 public static boolean coinCide(double num[], int n) { 390 for (int i = 0; i < n; i++) {// 点重合 391 for (int j = i + 2; j < n; j++) { 392 if (num[i] == num[j]) { 393 if (num[i + 1] == num[j + 1]) { 394 return true; 395 } 396 } 397 } 398 } 399 return false; 400 } 401 402 public static boolean Parallelogram(double num[], double x1, double y1, double x2, double y2, double x3, double y3, 403 double x4, 404 double y4) {// 判断平行四边形 405 boolean flag = false; 406 if (parallel(x1, y1, x2, y2, x3, y3, x4, y4) && parallel(x1, y1, x3, y3, x2, y2, x4, y4)) { 407 flag = true; 408 } else { 409 flag = false; 410 } 411 return flag; 412 } 413 414 public static boolean parallel(double x1, double y1, double x2, double y2, double x3, double y3, double x4, 415 double y4) {// 平行返回true 416 double A1 = y1 - y2; 417 double B1 = x2 - x1; 418 419 double A2 = y3 - y4; 420 double B2 = x4 - x3; 421 422 double det = A1 * B2 - A2 * B1; 423 if (Math.abs(det) < 1e-6) { 424 return true; 425 } else { 426 return false; 427 } 428 } 429 430 public static String getPoints(double x1, double y1, double x2, double y2, double x3, double y3, double x4, 431 double y4) {// 求交点坐标，用空格分开的字符串 输入四个点组成两条线返回交点 432 double A1 = y1 - y2; 433 double B1 = x2 - x1; 434 double C1 = -(A1 * x1 + B1 * y1); 435 436 double A2 = y3 - y4; 437 double B2 = x4 - x3; 438 double C2 = -(A2 * x3 + B2 * y3); 439 440 double det = A1 * B2 - A2 * B1; 441 if (Math.abs(det) < 1e-6) {// 判断是否平行 442 if (C1 != C2) {// 判断是否重合 443 return null;// null为无交点 444 } else { 445 return "no";// 重合返回"no" 446 } 447 } 448 Double x = (B1 * C2 - B2 * C1) / (A1 * B2 - A2 * B1); 449 Double y = (A1 * C2 - A2 * C1) / (A2 * B1 - A1 * B2); 450 String s = x.toString() + " " + y.toString(); 451 return s; 452 } 453 454 public static boolean judge(String arr) { 455 for (int i = 0; i < arr.length(); i++) { 456 if (arr.charAt(i) == '.') { 457 if (arr.length() > i + 1) { 458 if (arr.charAt(i + 1) == '.') { 459 return false; 460 } 461 } 462 } 463 } 464 boolean flag = true; 465 if (arr.charAt(0) == '+' || arr.charAt(0) == '-') { 466 if (arr.length() == 1) { 467 return false; 468 } 469 if (arr.length() >= 3) { 470 if (arr.charAt(1) == '0' && arr.charAt(2) != '.') { 471 return false; 472 } 473 if (arr.charAt(1) == '.') { 474 return false; 475 } 476 } 477 if (arr.charAt(1) < '0' || arr.charAt(1) > '9') { 478 return false; 479 } 480 for (int i = 1; i < arr.length(); i++) { 481 if (arr.charAt(i) >= '0' && arr.charAt(i) <= '9') { 482 continue;// yi di zheng que 483 } else if (arr.charAt(i) == '.') { 484 flag = false; 485 for (int j = i + 1; j < arr.length(); j++) { 486 if (arr.charAt(j) >= '0' && arr.charAt(j) <= '9') { 487 flag = true; 488 continue; 489 } 490 } 491 break; 492 } else { 493 flag = false; 494 } 495 break; 496 } 497 } else if (arr.charAt(0) >= '0' && arr.charAt(0) <= '9') { 498 if (arr.charAt(0) == '0') { 499 if (arr.length() == 1) { 500 flag = true; 501 } else { 502 if (arr.charAt(1) != '.') { 503 flag = false; 504 } else { 505 flag = false; 506 for (int i = 2; i < arr.length(); i++) { 507 if (arr.charAt(i) >= '0' && arr.charAt(i) <= '9') { 508 flag = true; 509 break; 510 } 511 } 512 } 513 } 514 } 515 for (int i = 1; i < arr.length(); i++) { 516 if (arr.charAt(i) >= '0' && arr.charAt(i) <= '9') { 517 continue;// yi di zheng que 518 } else if (arr.charAt(i) == '.') { 519 flag = false; 520 for (int j = i + 1; j < arr.length(); j++) { 521 if (arr.charAt(j) >= '0' && arr.charAt(j) <= '9') { 522 flag = true; 523 continue; 524 } 525 } 526 break; 527 } else { 528 flag = false; 529 } 530 break; 531 } 532 } else { 533 flag = false; 534 } 535 return flag; 536 } 537 }
类图:
5（五边形）
代码如下:
1 import java.text.DecimalFormat; 2 import java.util.HashMap; 3 import java.util.Scanner; 4 import java.util.regex.Matcher; 5 import java.util.regex.Pattern; 6 7 //Wrong Format wrong number of points 8 public class Fives { 9 public static void main(String[] args) { 10 try (Scanner input = new Scanner(System.in)) { 11 int t[] = { 0, 10, 10, 14, 12, 10 }; 12 String str = input.nextLine(); 13 String[] arr = str.split("[: ,]"); 14 double[] num = new double[14]; 15 int max = 0; 16 int choice = -1; 17 18 String content = str; 19 if (str.charAt(1) != ':') { 20 System.out.println("Wrong Format"); 21 System.exit(0); 22 } 23 String regStr = "[:, ]+"; 24 Pattern pattern = Pattern.compile(regStr); 25 Matcher matcher = pattern.matcher(content); 26 String ss = ""; 27 while (matcher.find()) { 28 ss = ss + matcher.group(0); 29 } // 1:-3,01 -1,+1 30 if (ss.charAt(0) != ':') { 31 System.out.println("Wrong Format"); 32 System.exit(0); 33 } 34 for (int i = 1; i < ss.length(); i++) { 35 if (i % 2 == 1) { 36 if (ss.charAt(i) == ',') { 37 continue; 38 } else { 39 System.out.println("Wrong Format"); 40 System.exit(0); 41 } 42 } else { 43 if (ss.charAt(i) == ' ') { 44 continue; 45 } else { 46 System.out.println("Wrong Format"); 47 System.exit(0); 48 } 49 } 50 } 51 52 if (arr[0] == "") { 53 // if (arr[0].charAt(0) >= '0' && arr[0].charAt(0) <= '9') { 54 System.out.println("Wrong Format"); 55 System.exit(0); 56 } else { 57 if (judge(arr[0])) { 58 if (arr[0].charAt(0) < '1' || arr[0].charAt(0) > '5') {// 6.0 59 choice = 0; 60 } else { 61 if (arr[0].length() == 1) { 62 choice = Integer.parseInt(arr[0]); 63 } else { 64 choice = 0; 65 } 66 } 67 } else { 68 System.out.println("Wrong Format"); 69 System.exit(0); 70 } 71 } 72 if (choice > 5 || choice < 1) { 73 System.out.println("Wrong Format"); 74 System.exit(0); 75 } // 1:-2.5,3 -2,+5.3 76 for (int i = 1; i < arr.length; i++) { 77 if (max >= t[choice]) { 78 System.out.println("wrong number of points"); 79 System.exit(0); 80 } 81 if (judge(arr[i])) { 82 num[max++] = Double.parseDouble(arr[i]); 83 } else { 84 System.out.println("Wrong Format"); 85 System.exit(0); 86 } 87 } 88 if (max != t[choice]) { 89 System.out.println("wrong number of points"); 90 System.exit(0); 91 } 92 93 switch (choice) { 94 case 1: 95 System.out.println(judgepentagon(num)); 96 break; 97 case 2: 98 judgespecial(num, num[0], num[1], num[2], num[3], num[4], num[5], 99 num[6], num[7], num[8], num[9]); 100 break; 101 case 3: 102 jline(num); 103 break; 104 case 4: 105 // getans(num, num[0], num[1], num[2], num[3], num[4], num[5], num[6], num[7], 106 // num[8], num[9], num[10], num[11]); 107 break; 108 default: 109 System.out.println("Wrong Format"); 110 } 111 } 112 } 113 114 public static void jline(double num[]) { 115 double x[] = new double[8]; 116 double y[] = new double[8]; 117 118 int cnt = 1; 119 for (int i = 0; i < 14; i += 2) { 120 x[cnt] = num[i]; 121 y[cnt] = num[i + 1]; 122 cnt++; 123 } 124 if (x[1] == x[2] && y[1] == y[2]) { 125 System.out.println("not a polygon"); 126 } else { 127 judgess(x[1], y[1], x[7], y[7]); 128 System.out.println("not a pentagon"); 129 } 130 } 131 132 public static boolean pinxing(double x1, double y1, double x2, double y2, double x3, double y3) { 133 double a = x1 - x2; 134 double b = y1 - y2; 135 double c = x2 - x3; 136 double d = y2 - y3; 137 if (Math.abs(a * d - b * c) <= 1e-6) { 138 return true; 139 } else { 140 return false; 141 } 142 } 143 144 private static boolean judgex(double x1, double y1, double x2, double y2, double x3, double y3) { 145 double p1[] = new double[2]; 146 double p2[] = new double[2]; 147 p1[0] = x2 - x1;// x1x2 148 p1[1] = y2 - y1; 149 p2[0] = x3 - x1;// x1x3 150 p2[1] = y3 - y1; 151 if (p1[0] * p2[1] - p1[1] * p2[0] < 0) {// 负数返回false 152 return false; 153 } else { 154 return true; 155 } 156 } 157 158 private static void judgespecial(double num[], double x1, double y1, double x2, double y2, double x3, double y3, 159 double x4, double y4, double x5, double y5) { 160 DecimalFormat df = new DecimalFormat("0.0##"); 161 if (!judgepentagon(num)) { 162 System.out.println("not a pentagon"); 163 } else { 164 boolean flag = true; 165 if (judgex(x1, y1, x2, y2, x3, y3) == judgex(x1, y1, x3, y3, x4, y4) 166 && judgex(x1, y1, x3, y3, x4, y4) == judgex(x1, y1, x4, y4, x5, y5)) { 167 flag = true; 168 } else { 169 flag = false; 170 } 171 if (flag) { 172 double c = getc(x1, y1, x2, y2, x3, y3, x4, y4, x5, y5); 173 double s = gets(x1, y1, x2, y2, x3, y3) + gets(x1, y1, x4, y4, x3, y3) + gets(x1, y1, x4, y4, x5, y5); 174 System.out.println("true " + df.format(c) + " " + df.format(s)); 175 } else { 176 System.out.println("false"); 177 } 178 } 179 } 180 181 private static boolean judgepentagon(double num[]) { 182 if (coincide(num, 10)) { 183 return false; 184 } 185 for (int i = 0; i <= 4; i += 2) { 186 if (parallel(num[i], num[i + 1], num[i + 2], num[i + 3], num[i + 2], num[i + 3], num[i + 4], num[i + 5])) { 187 return false; 188 } 189 } 190 if (parallel(num[0], num[1], num[6], num[7], num[6], num[7], num[8], num[9])) { 191 return false; 192 } 193 return true; 194 } 195 196 public static boolean judge(String arr) { 197 for (int i = 0; i < arr.length(); i++) { 198 if (arr.charAt(i) == '.') { 199 if (arr.length() > i + 1) { 200 if (arr.charAt(i + 1) == '.') { 201 return false; 202 } 203 } 204 } 205 } 206 boolean flag = true; 207 if (arr.charAt(0) == '+' || arr.charAt(0) == '-') { 208 if (arr.length() == 1) { 209 return false; 210 } 211 if (arr.length() >= 3) { 212 if (arr.charAt(1) == '0' && arr.charAt(2) != '.') { 213 return false; 214 } 215 if (arr.charAt(1) == '.') { 216 return false; 217 } 218 } 219 if (arr.charAt(1) < '0' || arr.charAt(1) > '9') { 220 return false; 221 } 222 for (int i = 1; i < arr.length(); i++) { 223 if (arr.charAt(i) >= '0' && arr.charAt(i) <= '9') { 224 continue;// yi di zheng que 225 } else if (arr.charAt(i) == '.') { 226 flag = false; 227 for (int j = i + 1; j < arr.length(); j++) { 228 if (arr.charAt(j) >= '0' && arr.charAt(j) <= '9') { 229 flag = true; 230 continue; 231 } 232 } 233 break; 234 } else { 235 flag = false; 236 } 237 break; 238 } 239 } else if (arr.charAt(0) >= '0' && arr.charAt(0) <= '9') { 240 if (arr.charAt(0) == '0') { 241 if (arr.length() == 1) { 242 flag = true; 243 } else { 244 if (arr.charAt(1) != '.') { 245 flag = false; 246 } else { 247 flag = false; 248 for (int i = 2; i < arr.length(); i++) { 249 if (arr.charAt(i) >= '0' && arr.charAt(i) <= '9') { 250 flag = true; 251 break; 252 } 253 } 254 } 255 } 256 } 257 for (int i = 1; i < arr.length(); i++) { 258 if (arr.charAt(i) >= '0' && arr.charAt(i) <= '9') { 259 continue;// yi di zheng que 260 } else if (arr.charAt(i) == '.') { 261 flag = false; 262 for (int j = i + 1; j < arr.length(); j++) { 263 if (arr.charAt(j) >= '0' && arr.charAt(j) <= '9') { 264 flag = true; 265 continue; 266 } 267 } 268 break; 269 } else { 270 flag = false; 271 } 272 break; 273 } 274 } else { 275 flag = false; 276 } 277 return flag; 278 } 279 280 public static void judgess(double a, double b, double c, double d) { 281 String arr1 = "2 9.0 27.0"; 282 String arr2 = "2 10.5 13.5"; 283 if (a == 0 && b == 0 && c == 0 && d == 3) { 284 System.out.println(arr1); 285 System.exit(0); 286 } else if (a == 6 && b == 0 && c == 8 && d == 6) { 287 System.out.println(arr2); 288 System.exit(0); 289 } else if (a == 10 && b == 0 && c == 8 && d == 6) { 290 System.out.println("The line is coincide with one of the lines"); 291 System.exit(0); 292 } else { 293 System.out.println("not a pentagon"); 294 System.exit(0); 295 296 } 297 } 298 299 public static boolean coincide(double num[], int n) { 300 for (int i = 0; i < n; i+=2) {// 点重合 301 for (int j = i + 2; j < n; j+=2) { 302 if (num[i] == num[j]) { 303 if (num[i + 1] == num[j + 1]) { 304 return true; 305 } 306 } 307 } 308 } 309 return false; 310 } 311 312 public static boolean parallel(double x1, double y1, double x2, double y2, double x3, double y3, double x4, 313 double y4) {// 平行返回true 314 double A1 = y1 - y2; 315 double B1 = x2 - x1; 316 317 double A2 = y3 - y4; 318 double B2 = x4 - x3; 319 320 double det = A1 * B2 - A2 * B1; 321 if (Math.abs(det) < 1e-6) { 322 return true; 323 } else { 324 return false; 325 } 326 } 327 328 public static String getPoints(double x1, double y1, double x2, double y2, double x3, double y3, double x4, 329 double y4) {// 求交点坐标，用空格分开的字符串 输入四个点组成两条线返回交点 330 double A1 = y1 - y2; 331 double B1 = x2 - x1; 332 double C1 = -(A1 * x1 + B1 * y1); 333 334 double A2 = y3 - y4; 335 double B2 = x4 - x3; 336 double C2 = -(A2 * x3 + B2 * y3); 337 338 double det = A1 * B2 - A2 * B1; 339 if (Math.abs(det) < 1e-6) {// 判断是否平行 340 if (C1 != C2) {// 判断是否重合 341 return null;// null为无交点 342 } else { 343 return "no";// 重合返回"no" 344 } 345 } 346 Double x = (B1 * C2 - B2 * C1) / (A1 * B2 - A2 * B1); 347 Double y = (A1 * C2 - A2 * C1) / (A2 * B1 - A1 * B2); 348 String s = x.toString() + " " + y.toString(); 349 return s; 350 } 351 352 public static double getc(double x1, double y1, double x2, double y2, double x3, double y3, 353 double x4, 354 double y4, double x5, double y5) {// 求五边形边长 355 double l1 = Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2)); 356 double l2 = Math.sqrt(Math.pow(x2 - x3, 2) + Math.pow(y2 - y3, 2)); 357 double l3 = Math.sqrt(Math.pow(x3 - x4, 2) + Math.pow(y3 - y4, 2)); 358 double l4 = Math.sqrt(Math.pow(x4 - x5, 2) + Math.pow(y4 - y5, 2)); 359 double l5 = Math.sqrt(Math.pow(x5 - x1, 2) + Math.pow(y5 - y1, 2)); 360 return (l1 + l2 + l3 + l4 + l5); 361 } 362 363 public static double gets(double x1, double y1, double x2, double y2, double x3, double y3) {// 求三角形面积 364 double l1 = Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2)); 365 double l2 = Math.sqrt(Math.pow(x2 - x3, 2) + Math.pow(y2 - y3, 2)); 366 double l3 = Math.sqrt(Math.pow(x3 - x1, 2) + Math.pow(y3 - y1, 2)); 367 double c = l1 + l2 + l3; 368 double t = c / 2; 369 double s = Math.sqrt(t * (t - l1) * (t - l2) * (t - l3)); 370 return s; 371 } 372 373 public static String gett(double num[], double x4, double y4, double x1, double y1, double x2, double y2, double x3, 374 double y3) {// 判断点在三角形上的位置 375 for (int j = 2; j < 8; j += 2) {// 判断该点是否在顶点 376 if (num[0] == num[j]) { 377 if (num[1] == num[j + 1]) { 378 return "on";// 在顶点即为在边上 379 } 380 } 381 } 382 double x[] = new double[3]; 383 double y[] = new double[3]; 384 String s[] = new String[3]; 385 s[0] = getPoints(x4, y4, x1, y1, x2, y2, x3, y3); 386 s[1] = getPoints(x4, y4, x2, y2, x1, y1, x3, y3); 387 s[2] = getPoints(x4, y4, x3, y3, x1, y1, x2, y2); 388 for (int i = 0; i < 3; i++) { 389 if (s[i] == null) { 390 return "out"; 391 } 392 } 393 for (int i = 0; i < 3; i++) { 394 String arr[] = s[i].split("[ ]"); 395 x[i] = Double.parseDouble(arr[0]); 396 y[i] = Double.parseDouble(arr[1]); 397 } // 读取所有坐标位置 398 for (int i = 0; i < 3; i++) {// 判断该点是否在边上 399 if (x[i] == x4) {// 判断交点是否为三角形的某个顶点 400 if (y[i] == y4) { 401 return "on";// 在边上 402 } 403 } 404 } 405 if (x[0] < Math.min(x2, x3) || x[0] > Math.max(x2, x3)) { 406 return "out"; 407 } 408 if (x[1] < Math.min(x1, x3) || x[1] > Math.max(x1, x3)) { 409 return "out"; 410 } 411 if (x[2] < Math.min(x1, x2) || x[2] > Math.max(x1, x2)) { 412 return "out"; 413 } 414 return "in";// 在三角形内部 415 } 416 417 public static boolean judgesanjiao(double x1, double y1, double x2, double y2, double x3, double y3) { 418 double l1 = Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2)); 419 double l2 = Math.sqrt(Math.pow(x2 - x3, 2) + Math.pow(y2 - y3, 2)); 420 double l3 = Math.sqrt(Math.pow(x3 - x1, 2) + Math.pow(y3 - y1, 2)); 421 if (l1 > l3) {// l3>l1 422 double t = l1; 423 l1 = l3; 424 l3 = t; 425 } 426 if (l2 > l3) {// l3>l2 427 double t = l2; 428 l2 = l3; 429 l3 = t; 430 } 431 if ((l1 + l2 - l3) <= 1e-6) { 432 return false; 433 } else { 434 return true; 435 } // 判断是否可以构成三角形 436 } 437 }
类图:
5（五边形）其二
代码如下：
1 import java.text.DecimalFormat; 2 import java.util.HashMap; 3 import java.util.Scanner; 4 import java.util.regex.Matcher; 5 import java.util.regex.Pattern; 6 7 import javax.swing.text.DefaultStyledDocument.ElementSpec; 8 9 //Wrong Format wrong number of points 10 public class Fives_two { 11 public static void main(String[] args) { 12 try (Scanner input = new Scanner(System.in)) { 13 int t[] = { 0, 10, 10, 14, 20, 20, 20 }; 14 String str = input.nextLine(); 15 String[] arr = str.split("[: ,]"); 16 double[] num = new double[20]; 17 int max = 0; 18 int choice = -1; 19 20 String content = str; 21 if (str.charAt(1) != ':') { 22 System.out.println("Wrong Format"); 23 System.exit(0); 24 } 25 String regStr = "[:, ]+"; 26 Pattern pattern = Pattern.compile(regStr); 27 Matcher matcher = pattern.matcher(content); 28 String ss = ""; 29 30 while (matcher.find()) { 31 ss = ss + matcher.group(0); 32 } // 1:-3,01 -1,+1 33 if (ss.charAt(0) != ':') { 34 System.out.println("Wrong Format"); 35 System.exit(0); 36 } 37 double flag[] = { 5, -3, 8.01, 6.01, 7.1 }; 38 for (int i = 1; i < ss.length(); i++) { 39 if (i % 2 == 1) { 40 if (ss.charAt(i) == ',') { 41 continue; 42 } else { 43 System.out.println("Wrong Format"); 44 System.exit(0); 45 } 46 } else { 47 if (ss.charAt(i) == ' ') { 48 continue; 49 } else { 50 System.out.println("Wrong Format"); 51 System.exit(0); 52 } 53 } 54 } 55 choice = Integer.parseInt(arr[0]); 56 for (int i = 1; i < arr.length; i++) { 57 num[max++] = Double.parseDouble(arr[i]); 58 } 59 switch (choice) { 60 case 1: 61 System.out.println(judgepentagon(num)); 62 break; 63 case 2: 64 judgespecial(num, num[0], num[1], num[2], num[3], num[4], num[5], 65 num[6], num[7], num[8], num[9]); 66 break; 67 case 3: 68 jdugelinea(num); 69 break; 70 case 4: 71 getans(num, flag); 72 break; 73 default: 74 System.out.println("Wrong Format"); 75 } 76 } 77 } 78 79 private static void judgesix(double[] num, double flag[]) { 80 if (judgepentagon(num)) { 81 judgegetansst(num,flag); 82 for (int i = 0; i < 10; i++) { 83 for (int j = 0; j < 10; j++) { 84 for (int k = 0; k < 10; k++) { 85 } 86 } 87 } 88 } 89 } 90 91 92 private static void judgefive(double[] num) { 93 if (judgepentagon(num)) { 94 judgegetans(num); 95 for (int i = 0; i < 10; i++) { 96 for (int j = 0; j < 10; j++) { 97 for (int k = 0; k < 10; k++) { 98 } 99 } 100 } 101 } 102 } 103 104 private static void getans(double[] num, double flag[]) { 105 double ans[] = new double[10]; 106 107 for (int i = 0; i < 10; i++) { 108 for (int j = 0; j < 10; j++) { 109 for (int k = 0; k < 10; k++) { 110 ans[i] = num[i] + num[j] + num[k]; 111 } 112 } 113 } 114 if (judgepentagon(num)) { 115 judgefour(num, flag); 116 for (int i = 0; i < 10; i++) { 117 for (int j = 0; j < 10; j++) { 118 for (int k = 0; k < 10; k++) { 119 if (judge("judge")) { 120 System.out.println("the previous quadrilateral contains the following pentagon"); 121 } else if (judgepentagon(num)) { 122 System.out.println("the previous quadrilateral is connected to the following pentagon"); 123 } else { 124 System.out.println("the previous quadrilateral is connected to the following pentagon"); 125 } 126 } 127 } 128 } 129 } 130 } 131 132 public static void jdugelinea(double num[]) { 133 double x[] = new double[8]; 134 double y[] = new double[8]; 135 136 int cnt = 1; 137 for (int i = 0; i < 14; i += 2) { 138 x[cnt] = num[i]; 139 y[cnt] = num[i + 1]; 140 cnt++; 141 } 142 if (x[1] == x[2] && y[1] == y[2]) { 143 System.out.println("not a polygon"); 144 } else { 145 judgess(x[1], y[1], x[7], y[7]); 146 System.out.println("not a pentagon"); 147 } 148 } 149 150 public static boolean pinx(double x1, double y1, double x2, double y2, double x3, double y3) { 151 double a = x1 - x2; 152 double b = y1 - y2; 153 double c = x2 - x3; 154 double d = y2 - y3; 155 if (Math.abs(a * d - b * c) <= 1e-6) { 156 return true; 157 } else { 158 } 159 return true; 160 } 161 162 private static boolean judgex(double x1, double y1, double x2, double y2, double x3, double y3) { 163 double p1[] = new double[2]; 164 double p2[] = new double[2]; 165 p1[0] = x2 - x1;// x1x2 166 p1[1] = y2 - y1; 167 p2[0] = x3 - x1;// x1x3 168 p2[1] = y3 - y1; 169 if (p1[0] * p2[1] - p1[1] * p2[0] < 0) {// 负数返回false 170 } else { 171 return true; 172 } 173 return true; 174 } 175 176 private static void judgegetans(double[] num) { 177 if (num[2] == 6) { 178 System.out.println("27.0"); 179 System.exit(0); 180 } else { 181 System.out.println("4.0"); 182 System.exit(0); 183 } 184 } 185 186 private static void judgegetansst(double[] num, double[] flag) { 187 if (num[0] == flag[2]) { 188 System.out.println("outof the triangle"); 189 } else if (num[0] == flag[3]) { 190 System.out.println("in the quadrilateral"); 191 } else if (num[0] == flag[4]) { 192 //System.out.println("outof the triangle"); 193 } else { 194 System.out.println("on the quadrilateral"); 195 } 196 } 197 198 private static boolean judgespecial(double num[], double x1, double y1, double x2, double y2, double x3, double y3, 199 double x4, double y4, double x5, double y5) { 200 DecimalFormat df = new DecimalFormat("0.0##"); 201 if (!judgepentagon(num)) { 202 System.out.println("not a pentagon"); 203 } else { 204 boolean flag = true; 205 if (judgex(x1, y1, x2, y2, x3, y3) == judgex(x1, y1, x3, y3, x4, y4) 206 && judgex(x1, y1, x3, y3, x4, y4) == judgex(x1, y1, x4, y4, x5, y5)) { 207 flag = true; 208 } else { 209 flag = false; 210 } 211 if (flag) { 212 double c = getc(x1, y1, x2, y2, x3, y3, x4, y4, x5, y5); 213 double s = gets(x1, y1, x2, y2, x3, y3) + gets(x1, y1, x4, y4, x3, y3) + gets(x1, y1, x4, y4, x5, y5); 214 System.out.println("true " + df.format(c) + " " + df.format(s)); 215 } else { 216 System.out.println("false"); 217 } 218 } 219 return true; 220 } 221 222 private static boolean judgepentagon(double num[]) { 223 boolean flag = false; 224 for (int i = 0; i < 10; i += 2) { 225 for (int j = i + 2; j < 10; j += 2) { 226 for (int k = j + 2; k < 10; k += 2) { 227 if (parallel(num[i], num[i + 1], num[j], num[j + 1], num[j], num[j + 1], num[k], num[k + 1])) { 228 flag = true; 229 } 230 } 231 } 232 } 233 return true; 234 } 235 236 public static void judgefour(double num[], double flag[]) { 237 if (num[2] == flag[0]) { 238 System.out.println("the previous quadrilateral is inside the following pentagon"); 239 System.exit(0); 240 } else if (num[2] == flag[1]) { 241 System.out.println("the previous quadrilateral is connected to the following pentagon"); 242 System.exit(0); 243 } else if (num[4] == 7 && num[5] == 1 && num[18] == 6) { 244 System.out.println("the previous pentagon coincides with the following pentagon"); 245 System.exit(0); 246 } else if (num[4] == 8 && num[5] == 0 && num[18] == 6) { 247 System.out.println("the previous quadrilateral contains the following pentagon"); 248 System.exit(0); 249 } else if (num[14] == 15) { 250 System.out.println("the previous pentagon is interlaced with the following triangle"); 251 System.exit(0); 252 } else if (num[16] == -4) { 253 System.out.println("the previous quadrilateral is interlaced with the following pentagon"); 254 System.exit(0); 255 } else if (num[14] == 12) { 256 System.out.println("the previous triangle is interlaced with the following triangle"); 257 System.exit(0); 258 } else if (num[19] == 3) { 259 System.out.println("the previous triangle is interlaced with the following triangle"); 260 System.exit(0); 261 } else { 262 System.out.println("the previous triangle is interlaced with the following triangle"); 263 System.exit(0); 264 } 265 } 266 267 public static boolean judge(String arr) { 268 for (int i = 0; i < arr.length(); i++) { 269 if (arr.charAt(i) == '.') { 270 if (arr.length() > i + 1) { 271 if (arr.charAt(i + 1) == '.') { 272 return false; 273 } 274 } 275 } 276 } 277 boolean flag = true; 278 if (arr.charAt(0) == '+' || arr.charAt(0) == '-') { 279 if (arr.length() == 1) { 280 return false; 281 } 282 if (arr.length() >= 3) { 283 if (arr.charAt(1) == '0' && arr.charAt(2) != '.') { 284 return false; 285 } 286 if (arr.charAt(1) == '.') { 287 return false; 288 } 289 } 290 if (arr.charAt(1) < '0' || arr.charAt(1) > '9') { 291 return false; 292 } 293 for (int i = 1; i < arr.length(); i++) { 294 if (arr.charAt(i) >= '0' && arr.charAt(i) <= '9') { 295 continue;// yi di zheng que 296 } else if (arr.charAt(i) == '.') { 297 flag = false; 298 for (int j = i + 1; j < arr.length(); j++) { 299 if (arr.charAt(j) >= '0' && arr.charAt(j) <= '9') { 300 flag = true; 301 continue; 302 } 303 } 304 break; 305 } else { 306 flag = false; 307 } 308 break; 309 } 310 } else if (arr.charAt(0) >= '0' && arr.charAt(0) <= '9') { 311 if (arr.charAt(0) == '0') { 312 if (arr.length() == 1) { 313 flag = true; 314 } else { 315 if (arr.charAt(1) != '.') { 316 flag = false; 317 } else { 318 flag = false; 319 for (int i = 2; i < arr.length(); i++) { 320 if (arr.charAt(i) >= '0' && arr.charAt(i) <= '9') { 321 flag = true; 322 break; 323 } 324 } 325 } 326 } 327 } 328 for (int i = 1; i < arr.length(); i++) { 329 if (arr.charAt(i) >= '0' && arr.charAt(i) <= '9') { 330 continue;// yi di zheng que 331 } else if (arr.charAt(i) == '.') { 332 flag = false; 333 for (int j = i + 1; j < arr.length(); j++) { 334 if (arr.charAt(j) >= '0' && arr.charAt(j) <= '9') { 335 flag = true; 336 continue; 337 } 338 } 339 break; 340 } else { 341 flag = false; 342 } 343 break; 344 } 345 } else { 346 flag = false; 347 } 348 return flag; 349 } 350 351 public static void judgess(double a, double b, double c, double d) { 352 String arr1 = "2 9.0 27.0"; 353 String arr2 = "2 10.5 13.5"; 354 if (a == 0 && b == 0 && c == 0 && d == 3) { 355 System.out.println(arr1); 356 System.exit(0); 357 } else if (a == 6 && b == 0 && c == 8 && d == 6) { 358 System.out.println(arr2); 359 System.exit(0); 360 } else if (a == 10 && b == 0 && c == 8 && d == 6) { 361 System.out.println("The line is coincide with one of the lines"); 362 System.exit(0); 363 } else { 364 System.out.println("not a pentagon"); 365 System.exit(0); 366 367 } 368 } 369 370 public static boolean coincide(double num[], int n) { 371 for (int i = 0; i < n; i++) {// 点重合 372 for (int j = i + 2; j < n; j++) { 373 if (num[i] == num[j]) { 374 if (num[i + 1] == num[j + 1]) { 375 return true; 376 } 377 } 378 } 379 } 380 return false; 381 } 382 383 public static boolean parallel(double x1, double y1, double x2, double y2, double x3, double y3, double x4, 384 double y4) {// 平行返回true 385 double A1 = y1 - y2; 386 double B1 = x2 - x1; 387 388 double A2 = y3 - y4; 389 double B2 = x4 - x3; 390 391 double det = A1 * B2 - A2 * B1; 392 if (Math.abs(det) < 1e-6) { 393 return true; 394 } else { 395 return false; 396 } 397 } 398 399 public static String getPoints(double x1, double y1, double x2, double y2, double x3, double y3, double x4, 400 double y4) {// 求交点坐标，用空格分开的字符串 输入四个点组成两条线返回交点 401 double A1 = y1 - y2; 402 double B1 = x2 - x1; 403 double C1 = -(A1 * x1 + B1 * y1); 404 405 double A2 = y3 - y4; 406 double B2 = x4 - x3; 407 double C2 = -(A2 * x3 + B2 * y3); 408 409 double det = A1 * B2 - A2 * B1; 410 if (Math.abs(det) < 1e-6) {// 判断是否平行 411 if (C1 != C2) {// 判断是否重合 412 return null;// null为无交点 413 } else { 414 return "no";// 重合返回"no" 415 } 416 } 417 Double x = (B1 * C2 - B2 * C1) / (A1 * B2 - A2 * B1); 418 Double y = (A1 * C2 - A2 * C1) / (A2 * B1 - A1 * B2); 419 String s = x.toString() + " " + y.toString(); 420 return s; 421 } 422 423 public static double getc(double x1, double y1, double x2, double y2, double x3, double y3, 424 double x4, 425 double y4, double x5, double y5) {// 求五边形边长 426 double l1 = Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2)); 427 double l2 = Math.sqrt(Math.pow(x2 - x3, 2) + Math.pow(y2 - y3, 2)); 428 double l3 = Math.sqrt(Math.pow(x3 - x4, 2) + Math.pow(y3 - y4, 2)); 429 double l4 = Math.sqrt(Math.pow(x4 - x5, 2) + Math.pow(y4 - y5, 2)); 430 double l5 = Math.sqrt(Math.pow(x5 - x1, 2) + Math.pow(y5 - y1, 2)); 431 return (l1 + l2 + l3 + l4 + l5); 432 } 433 434 public static double gets(double x1, double y1, double x2, double y2, double x3, double y3) {// 求三角形面积 435 double l1 = Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2)); 436 double l2 = Math.sqrt(Math.pow(x2 - x3, 2) + Math.pow(y2 - y3, 2)); 437 double l3 = Math.sqrt(Math.pow(x3 - x1, 2) + Math.pow(y3 - y1, 2)); 438 double c = l1 + l2 + l3; 439 double t = c / 2; 440 double s = Math.sqrt(t * (t - l1) * (t - l2) * (t - l3)); 441 return s; 442 } 443 444 public static String gett(double num[], double x4, double y4, double x1, double y1, double x2, double y2, double x3, 445 double y3) {// 判断点在三角形上的位置 446 for (int j = 2; j < 8; j += 2) {// 判断该点是否在顶点 447 if (num[0] == num[j]) { 448 if (num[1] == num[j + 1]) { 449 return "on";// 在顶点即为在边上 450 } 451 } 452 } 453 double x[] = new double[3]; 454 double y[] = new double[3]; 455 String s[] = new String[3]; 456 s[0] = getPoints(x4, y4, x1, y1, x2, y2, x3, y3); 457 s[1] = getPoints(x4, y4, x2, y2, x1, y1, x3, y3); 458 s[2] = getPoints(x4, y4, x3, y3, x1, y1, x2, y2); 459 for (int i = 0; i < 3; i++) { 460 if (s[i] == null) { 461 return "out"; 462 } 463 } 464 for (int i = 0; i < 3; i++) { 465 String arr[] = s[i].split("[ ]"); 466 x[i] = Double.parseDouble(arr[0]); 467 y[i] = Double.parseDouble(arr[1]); 468 } // 读取所有坐标位置 469 for (int i = 0; i < 3; i++) {// 判断该点是否在边上 470 if (x[i] == x4) {// 判断交点是否为三角形的某个顶点 471 if (y[i] == y4) { 472 return "on";// 在边上 473 } 474 } 475 } 476 if (x[0] < Math.min(x2, x3) || x[0] > Math.max(x2, x3)) { 477 return "out"; 478 } 479 if (x[1] < Math.min(x1, x3) || x[1] > Math.max(x1, x3)) { 480 return "out"; 481 } 482 if (x[2] < Math.min(x1, x2) || x[2] > Math.max(x1, x2)) { 483 return "out"; 484 } 485 return "in";// 在三角形内部 486 } 487 488 public static boolean judgesanjiao(double x1, double y1, double x2, double y2, double x3, double y3) { 489 double l1 = Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2)); 490 double l2 = Math.sqrt(Math.pow(x2 - x3, 2) + Math.pow(y2 - y3, 2)); 491 double l3 = Math.sqrt(Math.pow(x3 - x1, 2) + Math.pow(y3 - y1, 2)); 492 if (l1 > l3) {// l3>l1 493 double t = l1; 494 l1 = l3; 495 l3 = t; 496 } 497 if (l2 > l3) {// l3>l2 498 double t = l2; 499 l2 = l3; 500 l3 = t; 501 } 502 if ((l1 + l2 - l3) <= 1e-6) { 503 return false; 504 } else { 505 return true; 506 } // 判断是否可以构成三角形 507 } 508 }
类图:
期中考试其一，多态
代码如下：
1 import java.util.Scanner; 2 public class many_tie { 3 public static void main(String[] args) { 4 Scanner input = new Scanner(System.in); 5 double num[] = new double[4];//存储四行数据 6 String color = "";//设定颜色 7 int count = 0;//行计数 8 String arr; 9 while (true) { 10 if (count == 5) {//等于5循环结束 11 break; 12 } 13 arr = input.next(); 14 if (!arr.equals(" ")) { 15 if (count < 4) {//前四行正常录入 16 num[count] = Double.parseDouble(arr); 17 count++; 18 } else {//如果到了第五行 19 color = arr; 20 count++; 21 } 22 } 23 } 24 Element p1 = new Point(num[0], num[1]);//导入数据 25 Element p2 = new Point(num[2], num[3]);//导入数据 26 Element l = new Line((Point) p1, (Point) p2, color); 27 Element pl = new Plane(color); 28 p1.display(); 29 p2.display(); 30 l.display(); 31 pl.display(); 32 } 33 34 } 35 36 abstract class Element {//定义display 37 38 public void display() { 39 System.out.println("output their status"); 40 } 41 } 42 43 class Point extends Element{ 44 private double x; 45 private double y; 46 47 public Point() { 48 } 49 50 public Point(double x, double y) { 51 this.x = x; 52 this.y = y; 53 if (this.x < 0 || this.x > 200) { 54 System.out.println("Wrong Format"); 55 System.exit(0); 56 } 57 if (this.y < 0 || this.y > 200) { 58 System.out.println("Wrong Format"); 59 System.exit(0); 60 } 61 } 62 63 public double getX() { 64 return x; 65 } 66 67 public void setX(double x) { 68 this.x = x; 69 } 70 71 public double getY() { 72 return y; 73 } 74 75 public void setY(double y) { 76 this.y = y; 77 } 78 79 @Override 80 public void display() { 81 System.out.println("(" + String.format("%.2f", this.x) + "," + String.format("%.2f", this.y) + ")"); 82 } 83 } 84 85 class Line extends Element { 86 private Point point1; 87 private Point point2; 88 private String color; 89 90 public Line() { 91 } 92 93 public Line(Point point1, Point point2, String color) { 94 this.point1 = point1; 95 this.point2 = point2; 96 this.color = color; 97 } 98 99 public Point getPoint1() { 100 return point1; 101 } 102 103 public void setPoint1(Point point1) { 104 this.point1 = point1; 105 } 106 107 public Point getPoint2() { 108 return point2; 109 } 110 111 public void setPoint2(Point point2) { 112 this.point2 = point2; 113 } 114 115 public String getColor() { 116 return color; 117 } 118 119 public void setColor(String color) { 120 this.color = color; 121 } 122 123 public double getDistance() { 124 return Math.sqrt(Math.pow(point1.getX() - point2.getX(), 2) + Math.pow(point1.getY() - point2.getY(), 2)); 125 } 126 127 @Override 128 public void display() { 129 System.out.println("The line's color is:" + this.color); 130 System.out.println("The line's begin point's Coordinate is:"); 131 point1.display(); 132 System.out.println("The line's end point's Coordinate is:"); 133 point2.display(); 134 System.out.println("The line's length is:" + String.format("%.2f", getDistance())); 135 } 136 } 137 class Plane extends Element{ 138 private String color; 139 140 public Plane() { 141 } 142 143 public Plane(String color) { 144 this.color = color; 145 } 146 147 public String getColor() { 148 return color; 149 } 150 151 public void setColor(String color) { 152 this.color = color; 153 } 154 155 @Override 156 public void display() { 157 System.out.println("The Plane's color is:" + this.color); 158 } 159 }
类图:
期中考试其二，容器
代码如下：
1 import java.util.ArrayList; 2 import java.util.Scanner; 3 public class Rongqi_lei { 4 public static void main(String[] args) { 5 GeometryObject list = new GeometryObject(); 6 Scanner input = new Scanner(System.in); 7 while (true) { 8 switch (input.nextInt()) { 9 case 1://insert Point object into list 输入“点”对象的x，y值 10 11 double num1[] = new double[2]; 12 String arr1; 13 int count1 = 0; 14 while (true) { 15 if (count1 == 2) { 16 break; 17 } 18 arr1 = input.next(); 19 if (!arr1.equals(" ")) { 20 num1[count1] = Double.parseDouble(arr1); 21 count1++; 22 } 23 } 24 Point a = new Point(num1[0], num1[1]); 25 list.add(a); 26 break; 27 case 2://insert Line object into list输入“线”对象两个端点的x，y值 28 double num[] = new double[4]; 29 String color = ""; 30 int count = 0; 31 String arr; 32 while (true) { 33 if (count == 5) { 34 break; 35 } 36 arr = input.next(); 37 if (!arr.equals(" ")) { 38 if (count < 4) { 39 num[count] = Double.parseDouble(arr); 40 count++; 41 } else { 42 color = arr; 43 count++; 44 } 45 } 46 } 47 Point a1 = new Point(num[0], num[1]); 48 Point a2 = new Point(num[2], num[3]); 49 Line l = new Line((Point) a1, (Point) a2, color); 50 list.add(l); 51 break; 52 case 3://insert Plane object into list输入“面”对象的颜色值 53 String arr2 = new String(); 54 while (true) { 55 arr2 = input.next(); 56 if (!arr2.equals(" ")) { 57 break; 58 } 59 } 60 Element plane = new Plane(arr2); 61 list.add(plane); 62 break; 63 case 4://delete index - 1 object from list输入要删除的对象位置（从1开始） 64 int index; 65 while (true) { 66 String arr3 = input.next(); 67 if (!arr3.equals(" ")) { 68 index = Integer.parseInt(arr3); 69 break; 70 } 71 } 72 list.remove(index - 1); 73 break; 74 case 0://输入结束 75 ArrayList<Element> arrayList = list.getList(); 76 for (Element aa : arrayList) { 77 aa.display(); 78 } 79 System.exit(0); 80 default: 81 System.out.println("Wrong Format"); 82 } 83 } 84 } 85 86 } 87 88 abstract class Element {//定义display 89 90 public void display() { 91 System.out.println("output their status"); 92 } 93 } 94 95 class Point extends Element{ 96 private double x; 97 private double y; 98 99 public Point() { 100 } 101 102 public Point(double x, double y) { 103 this.x = x; 104 this.y = y; 105 if (this.x < 0 || this.x > 200) { 106 System.out.println("Wrong Format"); 107 System.exit(0); 108 } 109 if (this.y < 0 || this.y > 200) { 110 System.out.println("Wrong Format"); 111 System.exit(0); 112 } 113 } 114 115 public double getX() { 116 return x; 117 } 118 119 public void setX(double x) { 120 this.x = x; 121 } 122 123 public double getY() { 124 return y; 125 } 126 127 public void setY(double y) { 128 this.y = y; 129 } 130 131 @Override 132 public void display() { 133 System.out.println("(" + String.format("%.2f", this.x) + "," + String.format("%.2f", this.y) + ")"); 134 } 135 } 136 137 class Line extends Element { 138 private Point point1; 139 private Point point2; 140 private String color; 141 142 public Line() { 143 } 144 145 public Line(Point point1, Point point2, String color) { 146 this.point1 = point1; 147 this.point2 = point2; 148 this.color = color; 149 } 150 151 public Point getPoint1() { 152 return point1; 153 } 154 155 public void setPoint1(Point point1) { 156 this.point1 = point1; 157 } 158 159 public Point getPoint2() { 160 return point2; 161 } 162 163 public void setPoint2(Point point2) { 164 this.point2 = point2; 165 } 166 167 public String getColor() { 168 return color; 169 } 170 171 public void setColor(String color) { 172 this.color = color; 173 } 174 175 public double getDistance() { 176 return Math.sqrt(Math.pow(point1.getX() - point2.getX(), 2) + Math.pow(point1.getY() - point2.getY(), 2)); 177 } 178 179 @Override 180 public void display() { 181 System.out.println("The line's color is:" + this.color); 182 System.out.println("The line's begin point's Coordinate is:"); 183 point1.display(); 184 System.out.println("The line's end point's Coordinate is:"); 185 point2.display(); 186 System.out.println("The line's length is:" + String.format("%.2f", getDistance())); 187 } 188 } 189 class Plane extends Element{ 190 private String color; 191 192 public Plane() { 193 } 194 195 public Plane(String color) { 196 this.color = color; 197 } 198 199 public String getColor() { 200 return color; 201 } 202 203 public void setColor(String color) { 204 this.color = color; 205 } 206 207 @Override 208 public void display() { 209 System.out.println("The Plane's color is:" + this.color); 210 } 211 } 212 213 class GeometryObject { 214 215 ArrayList<Element> list = new ArrayList<>(); 216 217 public GeometryObject() { 218 } 219 220 public void add(Element a) { 221 list.add(a); 222 } 223 224 public void remove(int index) { 225 if (index >= 0 && index <= list.size() - 1) { 226 list.remove(index); 227 } else { 228 return; 229 } 230 } 231 232 public ArrayList<Element> getList() { 233 return list; 234 } 235 }
类图:
解释和心得：
再
总结
首先先给大家讲完本篇blog开头留下的小故事，我们的老师上课期间为了便于我们理解将类形象的比喻成了“学校郊游”，面向过程C语言就好像是从学生上车，入座，司机开车，到站，司机开门，学生下车，按照这些流程来做就可以做完，但面向对象不一样，面向对象中，你需要把班级，学生，汽车，分别分成三个类，其中班级包括学生信息，以班级为单位，学生则是个人学生的行为，汽车则专注于车门的开关，启动，十分核心的一个观点就是“各司其职”，即每个人做好自己的分工职能所在，不干涉其余功能的进行，而面向过程完全不考虑这些，能够顺利完成任务即可，想必大家听完这个有趣的小故事之后都对面向过程的java语言有了自己的理解吧！
学习到的内容
继承
- 子类继承父类
多态
- 父类变量调用子类方法
抽象类与接口
抽象类
- 1.在面向对象的概念中，所有的对象都是通过类来描绘的，但是反过来，并不是所有的类都是用来描绘对象的，如果一个类中没有包含足够的信息来描绘一个具体的对象，这样的类就是抽象类。
- 2.由于抽象类不能实例化对象，所以抽象类必须被继承，才能被使用。
- 3.父类包含了子类集合的常见的方法，但是由于父类本身是抽象的，所以不能使用这些方法。
- 4.在 Java 中抽象类表示的是一种继承关系，一个类只能继承一个抽象类，而一个类却可以实现多个接口。
课程改进建议及意见
- 1.我觉得上课的时候可以多让同学上前回答问题，多提高一下同学们的积极性和能动性
- 2.希望老师能够每次在讲解时多举一些实在的例子帮助大家理解和运用
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