While do while循环，for循环

While 循环

public class WhileDome01 {
    public static void main(String[] args) {
//        int a = 101;
//        int b = 50;
//        int c = 2;
//        System.out.println(101*50);
        // 计算 1+2+_+100 = ?
        int i = 0;
        int sum = 0;
        while(i<=100){
            sum += i++;

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

Do while循环

public class DowhileDemo02 {
    public static void main(String[] args) {
        int i = 0;
        int sum = 0;
        while (i<0){
            System.out.println(i);
        }
        System.out.println("==============");
        do {
            System.out.println(i);
        }while (i<0);
    }
}

for 循环

public class ForDome1 {
    public static void main(String[] args) {
//        for (int i = 1;i< 100; i+=2){
//
//            int sum = ;
//            System.out.println(i);

//        }
        int OddSum = 0;
        int EvenSum = 0;
        int b = 0;
        for (int i = 0; i <= 100; i++) {
            if(i <= 100){
                 b += i;
            }
            if (i%2 != 0){
                OddSum += i;
            }else{
                EvenSum += i;
            }
        }
        System.out.println(OddSum);
        System.out.println(EvenSum);
        System.out.println(EvenSum + OddSum);
        System.out.println("0到100的总和:" + b);

        System.out.println("====================");
        // 0~1000能除于5的，三个换一次行
        for (int i = 0; i <= 1000; i++) {
            if(i%5 == 0){
                System.out.print(i + "\t");
            }
            if (i%15 == 0) {
                System.out.print("\n");
            }
        }
	}
}

九九乘法表

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

public class forDemo5 {
    public static void main(String[] args) {
        int[] numbers = {0,11,22,33,44,55};
        for(int x:numbers){
            System.out.println(x);
        }
        System.out.println("==============");
        for(int i = 0; i<6;i++){
            System.out.println(numbers[i]);
        }
        System.out.println("==============");
        for(int i = 0; i<6;i++) {
            System.out.println(i);
        }
    }
}