Java第八周作业
上机练习
1、编写一个简单程序,要求数组长度为5,分别赋值10,20,30,40,50,在控制台输出该数组的值。(知识点:数组定义和创建、一维数组初始化)[必做题]•
1 package Exe; 2 3 import java.util.Scanner; 4 5 public class Exe1 { 6 7 /** 8 * @param args 9 */ 10 public static void main(String[] args) { 11 // TODO Auto-generated method stub 12 Scanner input = new Scanner(System.in); 13 int[] a = new int[5]; 14 for (int i = 0; i < a.length; i++) { 15 System.out.println("请输入第" + (i + 1) + "个赋值"); 16 a[i] = input.nextInt(); 17 } 18 for (int i = 0; i < a.length; i++) { 19 System.out.println("第" + (i + 1) + "个赋值" + a[i]); 20 } 21 22 } 23 24 }
2、将一个字符数组的值(neusofteducation)拷贝到另一个字符数组中。(知识点:数组复制) [必做题]•
package Exe; public class Exe2 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub String[] a = new String[] { "n", "e", "u", "s", "o", "f", "t" }; String[] b = new String[a.length]; System.arraycopy(a, 0, b, 0, a.length); System.out.println("b组:"); for (int i = 0; i < b.length; i++) { System.out.println(b[i]); } } }
3、给定一个有9个整数(1,6,2,3,9,4,5,7,8)的数组,先排序,然后输出排序后的数组的值。(知识点:Arrays.sort排序、冒泡排序)
Arrays.sort排序
package Exe; import java.util.Arrays; public class Exe3 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub int[] a = new int[] { 1, 6, 2, 3, 9, 4, 5, 7, 8 }; Arrays.sort(a); for (int i : a) { System.out.print(i+" "); } System.out.println(); } }
冒泡排序
package Class; import java.util.Scanner; public class Exe3 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub int[] a = { 1, 6, 2, 3, 9, 4, 5, 7, 8 }; for (int i = 0; i < a.length - 1; i++) { for (int j = 0; j < a.length - 1 - i; j++) { if (a[j] > a[j + 1]) { int temp = a[j]; a[j] = a[j + 1]; a[j + 1] = temp; } } } for (int i : a) { System.out.print(i + " "); } } }
4、 输出一个double型二维数组(长度分别为5、4,值自己设定)的值。(知识点:数组定义和创建、多维数组初始化、数组遍历)
package Exe; public class Exe4 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub double a[][] = new double[5][4]; for (int i = 0; i < a.length; i++) { for (int j = 0; j < a[i].length; j++) { a[i][j] = j; } } for (int i = 0; i < a.length; i++) { for (int j = 0; j < a[i].length; j++) { System.out.print(a[i][j] + " "); } System.out.println(); } } }
5、 在一个有8个整数(18,25,7,36,13,2,89,63)的数组中找出其中最大的数及其下标。(知识点:数组遍历、数组元素访问) [必做题]•
package Exe; public class Exe5 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub int[] a = new int[] { 18, 25, 7, 36, 13, 2, 89, 63 }; int max = a[0]; int i=1; for (i = 1; i < a.length; i++) { if (a[i] > max) { max = a[i]; } } System.out.println("最大数为" + max); System.out.println("下标为"+(i-1)); } }
作业
6、将一个数组中的元素逆序存放(知识点:数组遍历、数组元素访问) [选作题]•
package Homework; import java.util.Scanner; public class Home1 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub Scanner input = new Scanner(System.in); System.out.println("请输入数组中的元素个数"); int s = input.nextInt(); int[] a = new int[s]; for (int i = 0; i < s; i++) { System.out.println("请输入第" + (i + 1) + "个数"); a[i] = input.nextInt(); } System.out.println("倒序输出为"); for (int i = s - 1; i >= 0; i--) { System.out.println(a[i]); } } }
7. 将一个数组中的重复元素保留一个其他的清零。(知识点:数组遍历、数组元素访问) [选作题]课后作业•
package Homework; import java.util.Scanner; public class Home2 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub int[] a = { 1, 2, 3, 4, 4, 5, 6, 7 }; for (int i : a) { System.out.print(i + " "); } System.out.println(); for (int i = 0; i < a.length; i++) { for (int j = 0; j < a.length; j++) { if (a[i] == a[j] && i != j) a[j] = 0; } } System.out.println("将重复的元素清零后的数组:"); for (int i : a) { System.out.print(i + " "); } } }
8、给定一维数组{ -10,2,3,246,-100,0,5},计算出数组中的平均值、最大值、最小值。(知识点:数组遍历、数组元素访问)
package Homework; public class Home3 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub int[] a = { -10, 2, 3, 246, -100, 0, 5 }; int sum = 0; int max = a[0]; int min = a[0]; for (int i = 0; i < a.length; i++) { sum += a[i]; if (max < a[i]) max = a[i]; if (min > a[i]) min = a[i]; } System.out.println("平均数:" + sum / a.length); System.out.println("最大值:" + max); System.out.println("最小值:" + min); } }
9、使用数组存放裴波那契数列的前20项 ,并输出
package Homework; public class Home4 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub int[] a = new int[20]; a[0] = 1; a[1] = 1; for (int i = 2; i < a.length; i++) { a[i] = a[i - 1] + a[i - 2]; } for (int i = 0; i < a.length; i++) { System.out.println(a[i]); } } }
10、生成一个长度为10的随机整数数组(每个数都是0-100之间),输出,排序后,再输出
package Homework; import java.util.Random; public class Home5 { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub int[] a = new int[10]; Random sj = new Random(); System.out.println("产生的随机数组为"); for (int i = 0; i < a.length; i++) { a[i] = sj.nextInt(100); System.out.print(a[i] + " "); } System.out.println(); for (int i = 0; i < a.length - 1; i++) { for (int j = 0; j < a.length - 1 - i; j++) { if (a[j] > a[j + 1]) { int m = a[j]; a[j] = a[j + 1]; a[j + 1] = m; } } } System.out.println("排序后的数组为"); for (int i : a) { System.out.print(i + " "); } } }