双重for循环的几个例子

打印直角三角形

for(int x=1;x<=4;x++){
    for(int y=1;y<=x;y++){
	System.out.print("*");
    }
    System.out.println();
}

打印等腰三角形

for (int x = 1;x<=5 ;x++ ){
     for (int i = x;i<=4;i++ ){
         System.out.print(" ");
     }
     for (int y =1;y<=x ;y++ ){
         System.out.print("*"+" ");
     }
     System.out.println();
}
System.out.println("---------------");
for(int i = 1;i<=5;i++){
    for (int j = 0;j<=i-1 ;j++ ){
         System.out.print(" ");
    }
    for (int k = 5;k>=i ;k-- ){
         System.out.print("*"+" ");
    }
    System.out.println();
}

九九乘法

for(int x=1;x<=9;x++){
    for(int y=1;y<=x;y++){
	System.out.print(y+"×"+x+"="+y*x+"	");
    }
    System.out.println();
}