While循环和Do While循环

While循环

package com.tian.struct;

public class WhileDemo01 {
    public static void main(String[] args) {

        //输出1-100

        int i = 0;

        while (i<100){
            i++;
            System.out.println(i);
        }
    }
}

死循环

package com.tian.struct;

public class WhileDemo02 {
    public static void main(String[] args) {
        //死循环
        while (true){
            //等待客户端连接
            //定时检查
            //。。。。。。
        }
    }
}

例题

package com.tian.struct;

public class WhileDemo03 {
    public static void main(String[] args) {
        //计算1+2+3+...+100=?

        int i = 0;
        int sum = 0;

        while (i<=100){
            sum = sum+i;
            i++;
        }
        System.out.println(sum);
    }
}

DoWhile

示例

package com.tian.struct;

public class DoWhileDemo01 {
    public static void main(String[] args) {
        //计算1+2+3+...+100=?

        int i = 0;
        int sum = 0;

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

        System.out.println(sum);
    }
}

对比

package com.tian.struct;

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);
    }
}