day04

最新推荐文章于 2024-11-29 20:24:13 发布

原创最新推荐文章于 2024-11-29 20:24:13 发布 · 99 阅读

CC 4.0 BY-SA版权

本文展示了Java编程中使用`while`、`do-while`、`for`循环以及`if`、`switch`条件判断的实例。包括打印数字、执行特定操作、实现九九乘法表等，还涉及了标签（label）的使用以跳出多重循环。通过这些示例，读者可以深入理解控制流程语句在实际编程中的应用。

package day04;

public class BreakDemo01 {
    public static void main(String[] args) {

        int i = 0;

        while (i < 100){
            System.out.print(i +" ");
            i++;
            if (i > 30){
               break;
            }
        }
    }
}

package day04;

public class ContinueDemo01 {
    public static void main(String[] args) {

        int i = 0;

        while (i < 100){
            i++;
            if (i % 10 == 0){
                System.out.println();
                continue;
            }
            System.out.print(i + " ");
        }
    }
}

package day04;

public class DoWhileDemo01 {
    public static void main(String[] args) {

        int i = 1;
        int j = 0;

        do {
            j += i;
            i++;
        }while(i <= 100);

            System.out.println(j);
    }
}

package day04;

public class DoWhileDemo02 {
    public static void main(String[] args) {

        int a = 0;
        while (a < 0){
            System.out.println(a);
            a++;
        }

        System.out.println("---------------------------");

        do {
            System.out.println(a);
            a++;
        }while (a < 0);
    }
}

package day04;

public class ForDemo01 {
    public static void main(String[] args) {

        int a = 0;

        for (int i = 1;i <= 100;i++){
            System.out.print(i + " ");
            a++;
            if (a % 10 == 0){
                System.out.println();
            }
        }
    }
}

package day04;

public class ForDemo02 {
    //计算1 ~ 100所有基数和偶数的和
    public static void main(String[] args) {

        int a = 0;//偶数的和
        int b = 0;//基数的和

        for(int i = 1;i <= 100;i++){
            if (i % 2 == 0){
                System.out.print("偶数:" + i + " ");
                a += i;
            }
            else {
                System.out.print("基数:" + i + " ");
                b += i;
            }
        }

        System.out.println( "\n偶数的和为:" + a);
        System.out.println("基数的和为" + b);
        System.out.println("总和为:" + (a +b));
    }
}

package day04;

public class ForDemo03 {
    public static void main(String[] args) {

        //列出1~1000之间能被 5 整除的数，每行三个

        int j = 0;

        for(int i = 1;i <= 1000 ;i++ ){
            if (i % 5 == 0){
                System.out.print(i +" ");
                j++;
                if (j % 3 == 0){
                    System.out.println();
                }
            }
        }
    }
}

package day04;

public class ForDemo04 {
    public static void main(String[] args) {

        //九九乘法表
        for(int i = 1;i < 10;i++){
            for(int j = 1;j < i + 1; j++){
                System.out.print( i + "*" + j + "=" + i * j + " ");
            }
            System.out.println();
        }
    }
}

package day04;

public class ForDemo05 {
    public static void main(String[] args) {

        //增强型for循环

        int numbers[] = {12,43,12,323,12,3213,12,312};

        for (int a : numbers){
            System.out.print(a +" ");
        }
    }
}

package day04;

public class LableDemo01 {
    public static void main(String[] args) {

        //打印101~150之间的所有质数
        outer:for(int i = 101;i <= 150;i++){
            for (int j = 2;j < i / 2;j++){
                if (i % j == 0){
                    continue outer;
                }
            }
            System.out.print(i + " ");
        }
    }
}

package day04;

public class SwitchDemo01 {
    public static void main(String[] args) {

        char grade = 'C';

        switch (grade){
            case 'A':
                System.out.println("优秀");
                break;
            case 'B':
                System.out.println("良好");
                break;
            case 'C':
                System.out.println("及格");
                break;
            case 'D':
                System.out.println("不及格");
            default:
                System.out.println("输入无法解析!");
        }
    }
}

package day04;

public class SwitchDemo02 {
    public static void main(String[] args) {

        String str = "语文";
        switch (str){
            case "科学":
                System.out.println("欢迎来到科学");
                break;
            case "数学":
                System.out.println("欢迎来到数学");
                break;
            case "语文":
                System.out.println("欢迎来到语文");
                break;
            default:
                System.out.println("输入错误!");
        }
    }
}

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package day04;

public class SwitchDemo02 {
    public SwitchDemo02() {
    }

    public static void main(String[] args) {
        String str = "语文";
        byte var3 = -1;
        switch(str.hashCode()) {
        case 828406:
            if (str.equals("数学")) {
                var3 = 1;
            }
            break;
        case 990133:
            if (str.equals("科学")) {
                var3 = 0;
            }
            break;
        case 1136442:
            if (str.equals("语文")) {
                var3 = 2;
            }
        }

        switch(var3) {
        case 0:
            System.out.println("欢迎来到科学");
            break;
        case 1:
            System.out.println("欢迎来到数学");
            break;
        case 2:
            System.out.println("欢迎来到语文");
            break;
        default:
            System.out.println("输入错误!");
        }

    }
}

package day04;

public class TestDemo {
    public static void main(String[] args) {
        //打印三角形
        for (int i = 1; i <= 5; i++) {
            //打印空白的三角形
            for (int j = 5; j >= i; j--) {
                System.out.print(" ");
            }
            //打印一半的三角形
            for (int j = 1;j <= i; j++){
                System.out.print("*");
            }
            //补全三角形
            for (int j = 2;j <= i;j++){
                System.out.print("*");
            }
            System.out.println();
            //太妙了
        }
    }
}

package day04;

public class Whiledemo01 {
    public static void main(String[] args) {
        //输出 1 ~ 100

        int i = 1;
        int j = 0;
        while (i <= 100){
            System.out.print(i + " ");
            i++;
            j++;
            if (j % 10 == 0){
                System.out.println();
            }
        }
    }
}

package day04;

public class Whiledemo02 {
    public static void main(String[] args) {
        //计算1+2+3....+100

        int i = 1;
        int j = 0;

        while (i <= 100){
//            System.out.println("加" + i);
            j += i;
            i++;

        }
        System.out.println(j);
    }
}