69期-Java SE-004_循环、数组-001-002

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<i+1;j++) {
                System.out.print(" ");
            }
            for(int k=2-i;k<5-2*i;k++) {
                System.out.print(k+" ");
            }
            System.out.println("");
        }
    }
}

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};
    }
}