JAVA循环结构练习

练习1：计算0-100之间的奇数和偶数的和

public class rug {
    public static void main(String[] args) {
        int oddSum = 0;
        int evenSum = 0;
        for (int i = 0; i < 100; i++) {
            if (i%2 != 0){
                oddSum += i;
            }else {
                evenSum += i;
            }
        }
        System.out.println(oddSum);
        System.out.println(evenSum);
    }
}

练习2：输出1-1000之间能被5整除的数，并且每行输出3个

public class rug {
    public static void main(String[] args) {
        for (int i = 0; i <= 1000; i++) {
            if (i % 5 == 0){
                System.out.print(i + "\t");
            }
            if (i %(5*3)==0){	//每行输出三个
                System.out.println();
            }
        }
    }
}

9*9乘法表

public class rug {
    public static void main(String[] args) {
        /*
        1.先打印第一行
        2.把固定的1用循环包起来
        3.去掉重复项，i <= j
        4.调整样式
        */
        for (int j = 1; j <= 9; j++) {
            for (int i = 1; i <= j; i++) {
                System.out.print(j + "*" + i + "=" + (j*i) + "\t");
            }
            System.out.println();
        }
    }
}

1.打印第一行

for (int i = 1; i <= 9; i++){
	System.out,println(j + "*" + i + "=" + (j*i) + "\t");
}

2.把1包起来

for (int i = 1; i <= 9; i++) {
     for (int i = 1; i <= 9; i++) {
          System.out.print(j + "*" + i + "=" + (j*i) + "\t");       
     }

3.把重复项1去掉

for (int j = 1; j <= 9; j++) {	//把i换成j
     for (int i = 1; i <= j; i++) {
          System.out.print(j + "*" + i + "=" + (j*i) + "\t");
     }