为什么这个println不能整个执行？

Question

I'm new to programming and trying to understand this nested for loop completely. The println is part of the body of the inner loop. However, it is not being executed with the inner loop iteration. I don't want to execute it, but I'm just trying to understand why the inner loop body isn't executed completely?

int rowNum, colNum;
    for (rowNum = 1; rowNum <= 3; rowNum++) 
    {
     for (colNum = 1; colNum <= 2; colNum++) 
            System.out.print(" rowNum: " + rowNum + " colNum: " + colNum);
        System.out.println();

    }

If the println() were executed with the body I would get something like this:

 rowNum: 1 colNum: 1
 rowNum: 1 colNum: 2
 rowNum: 2 colNum: 1
 rowNum: 2 colNum: 2
 rowNum: 3 colNum: 1
 rowNum: 3 colNum: 2

Instead, I'm getting this:

 rowNum: 1 colNum: 1 rowNum: 1 colNum: 2
 rowNum: 2 colNum: 1 rowNum: 2 colNum: 2
 rowNum: 3 colNum: 1 rowNum: 3 colNum: 2

Again, I just want to understand why, not how to fix it... Thanks!

Answer 1

for loop execute only next 1 line if curly brackets are not provided. if you give curly brackets between second for loop and after println();. you will get want you want.

System.out.print(" xxx "); System.out.println();

this will give you xxx xxx xxx xxx

because it is print println print 2 times then line comes.

edit first System.out.println(" rowNum: " + rowNum + " colNum: " + colNum);

and remove second println.

Answer 2

rowNum: 1 colNum: 1 rowNum: 1 colNum: 2 rowNum: 2 colNum: 1 rowNum: 2 colNum: 2 rowNum: 3 colNum: 1 rowNum: 3 colNum: 2

This is because you print 2 times before getting out of the loop and print a new line.