4. 循环语句

循环语句

1. while语句

package com.lin.study.xunhuan;
​
public class WhileDemo {
    public static void main(String[] args) {
        //计算1+2+3+...+100=?
        int i = 0,sum = 0;
​
        while(i<=100){
            sum = sum + i;
            i++;
        }
​
        System.out.println("sum=" + sum);
    }
}

运行结果:

sum=5050

Process finished with exit code 0

2. do...while语句

do...while语句，至少会执行一次。

package com.lin.study.xunhuan;
​
public class DoWhileDemo {
    public static void main(String[] args) {
        //计算1+2+3+...+100=?
        int i = 0,sum = 0;
​
        do{
            sum = sum + i;
            i++;
        }while(i<=100);
​
        System.out.println("sum= " + sum);
    }
}

运行结果:

sum= 5050

Process finished with exit code 0

3. while语句 与 do...while语句 的对比

package com.lin.study.xunhuan;
​
public class Demo {
    public static void main(String[] args) {
        //对比while与do...while
        int a = 0;
​
        while(a<0){
            a++;
            System.out.println(a);
        }
​
        System.out.println("-----------------------------------");
​
        do{
            a++;
            System.out.println(a);
        }while(a<0);
    }
}

运行结果:

---

1

Process finished with exit code 0