Java中的Loop inside Loop（简单）

Question

I am doing an exercise where I have to print 'x' (is an input) rows of numbers incrementing from 0 to 10. If I input 3, the output should look like this

012
345
678

012
345
678

012
345
678

but instead, I get 3 rows of a 0 to 10 count.
I know it might be easy to code, but I am stuck in that!
I think I am not undestanding well the nested loops:(

public class quadrats {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);
        int q = in.nextInt();

        for (int j = 0; j < q; j++) {
            for (int i = 0; i <= 10; i++) {
                System.out.print(i);
            } 
            System.out.println();
        } 
    }

}

Answer 1

You don't need two loops for this. All you need is to print a newline after every 3rd letter and an extra newline after every 3rd line. Your code can be like:

public class quadrats {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);
        int q = in.nextInt();
        int lines = 0;
        int letters = 0;
        while (lines < q) {
            System.out.print(i);

            if (letters && letters % q == 0) {
                System.out.println();
                lines++;
            }
            if (lines && lines % q == 0) {
                System.out.println();
                letters = 0;
                continue;
            }
            letters++;
        }
}

PS: I haven't tried this code myself. But concept would be the same.

Answer 2

You can try with below code

public class quadrats {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);
        int q = in.nextInt();

        for (int j = 0; j < q; j++) {
            for (int i = 0; i < 9; i++) {
                if(i%3 == 0)
                   System.out.println();
                System.out.print(i);
            } 
            System.out.println();
        } 
    }
}

Answer 3

The answer above should solve your problem so I will try to explain what your code does.

Let's start with code inside first for loop:

for (int i = 0; i <= 10; i++) {
   System.out.print(i);
} 
System.out.println();

First we have a loop iterating through numbers from 0 to 10 and the output is:

012345678910

and a new line after that.

That means that output of your program will print above mentioned output q times.

012345678910

012345678910

012345678910

Answer 4

Print X quandrants of X rows and X columns each

Scanner in = new Scanner(System.in);
int q = in.nextInt();

// q quadrants
for (int iQuadrat = 0; iQuadrat < q; iQuadrat++) {

    // count will keep track of the last number you print
    int count = 0;
    // q rows
    for (int iRow = 0; iRow < q; iRow++) {
        // q cols
        for (int iCol = 0; iCol < q; iCol++) {
            System.out.print(count);
            // increment the count and take its modulo 10 so it stays between 0 and 9
            count = (count+1)%10;
        }
        // line return at the end of the row
        System.out.println();
    }
    // line return between quadrants
    System.out.println();
}

For an input of 12, it will print 12 times this quadrant

012345678901
234567890123
456789012345
678901234567
890123456789
012345678901
234567890123
456789012345
678901234567
890123456789
012345678901
234567890123