for循环

for(初始化；布尔表达式；更新){
    //代码块
}    

package com.steven.demo;

public class ForDemo1 {
    public static void main(String[] args) {
        int sum = 0;
        int peace = 0;
        for(int i = 0; i <= 100;i++){
            if(i%2==0){
                sum = sum + i;
            }else{
                peace = peace + i;
            }
        }
        System.out.println("100以内偶数和：" +sum);
        System.out.println("100以内奇数和：" +peace);
    }
}

package com.steven.demo;

public class ForDemo3 {
    public static void main(String[] args) {
        int j = 0;
        for(int i = 1; i <= 100;i++){
            if (i % 5 == 0){
                System.out.print(i + " ");
                j++;
                if(j%5==0){
                    System.out.println();
                }
            }
        }
    }
}

package com.steven.demo;

public class ForDemo2 {
    public static void main(String[] args) {
        for(int i = 1; i <= 9; i++){
            for (int j = 1; j <= i; j++){
                System.out.print(j + "*" + i +"="+ i*j+"  ");
            }
            System.out.println();
        }
    }
}