For loop to print a numeric pattern does not print the correct pattern

This is what it should look like

9 8 7 6 5 4 3 2 1 0

8 8 7 6 5 4 3 2 1 0 

7 7 7 6 5 4 3 2 1 0

6 6 6 6 5 4 3 2 1 0

5 5 5 5 5 4 3 2 1 0

4 4 4 4 4 4 3 2 1 0

3 3 3 3 3 3 3 2 1 0

2 2 2 2 2 2 2 2 1 0

1 1 1 1 1 1 1 1 1 0

0 0 0 0 0 0 0 0 0 0

Here's my attempt.

public class Main {
	public static void main(String[] args) {
		int i = 9;
		int count = -1;
		while (i >= count) {
			int j = i;
			while (j > count) {
				System.out.print(j + " ");
				j--;
			}
			System.out.println();
			count++;
		}
	}
}

Here's my actual output:

9 8 7 6 5 4 3 2 1 0 
9 8 7 6 5 4 3 2 1 
9 8 7 6 5 4 3 2 
9 8 7 6 5 4 3 
9 8 7 6 5 4 
9 8 7 6 5 
9 8 7 6 
9 8 7 
9 8 
9 

This obviously does not match the expected output. Can someone point out where the mistake is in the code?

This is a Solution that has the right output, but instead of using while-Loops I used for-Loops

public class Main {
    public static void main(String[] args) {
        int count1 = 9;
        for (int i = count1; i >= 0; i--) {
            int count2 = i;
            if (count1 > count2) {
                int tmp = count1 - count2;
                for (int j = tmp; j > 0; j--) {
                    System.out.print(count2 + " ");
                }
            }
            for (int j = count2; j >= 0; j--) {
                System.out.print(j + " ");
            }
            System.out.println();
        }
    }
}

You can keep two outer variables, counter and multiplier, for the matrix size and repetitions' count respectively:

public class Main {
    public static void main(String[] args) {
        int counter = 15;
        int multiplier = 1;
        for (int i = counter; i >= 0; i--) {
            for (int j = 0; j<multiplier; j++) {
                System.out.printf("%3d", counter); //using %3d for spacing numbers nicely
            }
            for (int k = counter-1; k >= 0; k--) {
                System.out.printf("%3d", k);
            }
            ++multiplier;
            --counter;
            System.out.println();
        }
    }
}

For every horizontal line, where counter decreases, and multiplier increases (9 once on 1st line; 8 twice on the second line, etc.):

• it will first print the counter, multiplier times;
• it will then fill the rest of the line with counter-multiplier number of descending sequence integers, starting from counter-1;
• at the end of outer loop's each iteration, a new line is printed.

Output would be:

9  8  7  6  5  4  3  2  1  0
8  8  7  6  5  4  3  2  1  0
7  7  7  6  5  4  3  2  1  0
6  6  6  6  5  4  3  2  1  0
5  5  5  5  5  4  3  2  1  0
4  4  4  4  4  4  3  2  1  0
3  3  3  3  3  3  3  2  1  0
2  2  2  2  2  2  2  2  1  0
1  1  1  1  1  1  1  1  1  0
0  0  0  0  0  0  0  0  0  0

Since you already have your answer, here are a couple alternatives.

String str = "9 8 7 6 5 6 3 2 1 0";
System.out.println(str);
for (int i = 9; i > 0; i--) {
	str = str.replace(i+"",(i-1)+"");
	System.out.println(str);
}

Or use the String.repeatmethod.

for (int i = 9; i >= 0; i--) {
	System.out.print((i+" ").repeat(9-i));
	for(int k = i; k >= 0; k--) {
		System.out.print(k + " ");
	}
	System.out.println();
}

</details>



# 答案4
**得分**: 0

用Java8的流(Stream)功能，你可以将代码编写如下：

```java
public static void main(String[] args) {
    IntStream.range(0, 10)
        .forEach(i -> {
            IntStream.range(0, 10).forEach(j -> {
                System.out.print((9 - (j < i ? i : j)) + " ");
            });
            System.out.println("");
        });
}

public static void main(String[] args) {
    	
    	IntStream.range(0, 10)
        .forEach(i -> {
        	IntStream.range(0, 10).forEach(j -> {
    			
    			System.out.print((9- (j < i ? i : j)) + " " );
        		
        	});
        	System.out.println("");
        });
    }