Hello.java

import java.util.Scanner;public class Hello {    public static void main(String[] args) {        Scanner scanner = new Scanner(System.in);        String str = "yes";        int num;        while(str.equals("yes")) {            System.out.print("请输入学生编号：");            num = scanner.nextInt();            switch(num) {            case 1:                System.out.println("张三的成绩为90");                break;            case 2:                System.out.println("李四的成绩为80");                break;            case 3:                System.out.println("王五的成绩为70");                break;            default:                System.out.println("输入有误！");                break;            }            System.out.print("是否继续？yes/no");            str = scanner.next();        }        System.out.println("查询结束");    }}

 

Test.java

import java.util.Scanner;public class Test {    public static void main(String[] args) {//        int num = 0;//        do {//            System.out.println("Hello World");//            num++;//        }while(num < 0);        String str;        Scanner scanner = new Scanner(System.in);        do {            System.out.println("张三参加体能测试，跑1000米...");            System.out.print("是否合格？yes/no");            str = scanner.next();        }while(str.equals("no"));        System.out.println("合格，通过测试");    }}

 

Test2.java

public class Test2 {    public static void main(String[] args) {        for(int i = 0;i < 10;i++) {            System.out.println("Hello World");        }    }}

 

Test3.java

public class Test3 {    public static void main(String[] args) {        //while循环        int num = 0;        while(num <= 10) {            if(num%2!=0) {                System.out.print(num+",");            }            num++;        }        System.out.println("");        //do-while循环        num = 0;        do {            if(num%2!=0) {                System.out.print(num+",");            }            num++;        }while(num<=10);        System.out.println("");        //for循环        for(int i = 0;i <= 10;i++) {            if(i%2!=0) {                System.out.print(i+",");            }        }    }}

 

Test4.java

public class Test4 {    public static void main(String[] args) {        //打印1-6//        for(int i=1;i<=6;i++) {//            System.out.print(i+" ");//        }//        System.out.println("");//        for(int i=1;i<=6;i++) {//            System.out.print(i+" ");//        }//        System.out.println("");//        for(int i=1;i<=6;i++) {//            System.out.print(i+" ");        //        for(int j=0;j<10;j++) {//            for(int i=1;i<=6;i++) {//                System.out.print(i+" ");//            }//            System.out.println("");//        }                for(int i=0;i<4;i++) {            for(int j=0;j<3-i;j++) {                System.out.print(" ");            }            for(int k=i;k<2*i+1;k++) {                System.out.print(k+" ");            }            System.out.println("");        }        for(int i=0;i<3;i++) {            for(int j=0;j

 

Test5.java

public class Test5 {    public static void main(String[] args) {//        int sum = 0;//        for(int i=1;i<=100;i++) {//            sum += i;//            if(sum>50) {//                break;//            }//        }//        System.out.println("1-100的总和是"+sum);        int sum = 0;        for(int i=1;i<=200;i++) {//            if(i%2!=0) {//                sum+=i;//            }            if(i%2==0) {                continue;            }            sum+=i;        }        System.out.println("1-200的奇数之和是"+sum);    }}

 

Test6.java

public class Test6 {    public static void main(String[] args) {        //声明数组：数据类型[] 数组名        int[] array1;        String array2[];        //分配内存空间：创建数组必须指定长度，根据长度开辟一串连续的内存空间，长度不能修改        array1 = new int[6];        array2 = new String[7];        //给数组赋值        array1[0] = 50;        array1[1] = 60;        array2[1] = "Hello World";        //使用数组        System.out.println(array1[0]);    }}

 

Test7.java

public class Test7 {    public static void main(String[] args) {//        int[] array;//        array = new int[4];        int[] array = new int[4];        array[0] = 179;        array[1] = 182;        array[2] = 168;        array[3] = 176;        System.out.println(array[4]);//        //计算平均值//        double sum = 0;//        for(int i=0;i<4;i++) {//            sum += array[i];//        }//        System.out.println("平均身高是"+sum/4);//        int[] array1 = {179,182,168,176};//        int[] array1 = new int[4];//        array1 = {179,182,168,176};    }}