第六次Java作业
1.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
package jiji;
import java.util.Arrays;
public class Dsa {
public static void main(String[] args) {
// TODO Auto-generated method stub
int a[] = { 1, 6, 2, 3, 9, 4, 5, 7, 8 };
System.out.println("Arrays.sort排序:");
Arrays.sort(a);
for (int i : a) {
System.out.println(i);
}
System.out.println("冒泡排序:");
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.println(i);
}
}
}
2.输出一个double型二维数组（长度分别为5、4，值自己设定）的值。
package jiji;
public class Dsa {
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] = i;
}
}
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();
}
}
}
3.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。
package jiji;
public class Dsa {
public static void main(String[] args) {
// TODO Auto-generated method stub
int a[]={18,25,7,36,13,2,89,63};
int max=a[0];
int index=0;
for (int i = 0; i < a.length; i++) {
if (a[i]>max) {
max=a[i];
index=i;
}
}
System.out.println("数组中的最大值为"+max);
System.out.println("下标为"+index);
}
}
4.将一个数组中的元素逆序存放
package jiji;
public class Dsa {
public static void main(String[] args) {
// TODO Auto-generated method stub
int a[]={18,25,7,36,13,2,89,63};
System.out.println("倒序后为：");
for (int i = 7; i >= 0; i--) {
System.out.print (" "+a[i]);
}
}
}
5.将一个数组中的重复元素保留一个其他的清零。
package jiji;
public class Dsa {
public static void main(String[] args) {
// TODO Auto-generated method stub
int a[]={18,25,7,36,13,2,89,63,25,18};
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;
}
}
}
for (int i : a) {
System.out.print(" "+i);
}
}
}
6.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。
package jiji;
public class Dsa {
public static void main(String[] args) {
// TODO Auto-generated method stub
int a[]={-10,2,3,246,-100,0,5};
int max=a[0];
int min=a[0];
double sum=0;
for (int i = 0; i < a.length; i++) {
if (max<a[i]) {
max=a[i];
}
if (min>a[i]) {
min=a[i];
}
sum+=a[i];
}
sum=sum/7;
System.out.println("最大值"+max);
System.out.println("最小值"+min);
System.out.println("平均值"+sum);
}
}
7.使用数组存放裴波那契数列的前20项 ，并输出
package jiji;
public class Dsa {
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 < 8; i++) {
System.out.print(a[i] + " ");
}
}
}
8.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 jiji;
import java.util.Arrays;
import java.util.Random;
public class Dsa {
public static void main(String[] args) {
// TODO Auto-generated method stub
Random r = new Random();
int a[] = new int[10];
for (int i = 0; i < a.length; i++) {
a[i] = r.nextInt(101);
}
for (int i = 0; i < a.length; i++) {
System.out.print(a[i] + " ");
}
Arrays.sort(a);
System.out.println();
for (int i = 0; i < a.length; i++) {
System.out.print(a[i]+" ");
}
}
}
9.做一个菜单切换程序，主菜单1注册2登录3幸运抽奖4退出
package jiji;
import java.util.Scanner;
public class Dsa {
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println("1.登录");
System.out.println("2.注册");
System.out.println("3.幸运抽奖");
System.out.println("4.退出");
Scanner input = new Scanner(System.in);
int i = input.nextInt();
switch (i) {
case 1:
login();
break;
case 2:
zhuce();
break;
}
}
public static void login() {
System.out.println("輸入用戶名");
Scanner input = new Scanner(System.in);
String name = input.next();
System.out.println("输入密码");
String pwd = input.next();
if (name.equals(pwd)) {
System.out.println("登录成功");
} else {
System.out.println("登录失败");
}
System.out.println("是否返回主菜单？Y/N");
if (input.next().equalsIgnoreCase("y")) {
showMain();
} else {
System.out.println("谢谢使用");
}
}
public static void zhuce() {
System.out.println("请输入用户名");
Scanner input = new Scanner(System.in);
String name = input.next();
System.out.println("输入密码");
String pwd = input.next();
System.out.println("注册成功");
System.out.println("是否返回主菜单？Y/N");
if (input.next().equalsIgnoreCase("y")) {
showMain();
} else {
System.out.println("谢谢使用");
}
}
public static void main(String[] args) {
showMain();
}
}
