Java使用for循环打印某些模式

Question

below are my code can anyone help me i stuck at the * part

i want the output like this

     9
    989
   98789
  9876789
 987656789

... and so on

    for (int i = 1; i <= l; i++) {
        for (int j = 1; j <= l - i; j++)
            System.out.print(" ");

        for (int j = 1; j <= (2 * i - 1); j++) {
            if((l-j) < l-i){
            // here System.out.print("*");
            }
            else
                System.out.print(l - j);

        }
        System.out.print("\n");
    }

Answer 1

I ended up rewriting it; I couldn't figure out a concise constant for the print you were missing. If you loop i from 0 to l (inclusive), you can do:

Spaces

The last line ( i = l ) has 0 spaces, so each line has li spaces:

for(int j = 0; j < l-i; j++)
    System.out.print(" ");

Left/Center

Every line starts at l , and you want to count down till you reach the center; since the current line has li spaces and the center is at l+1 (since I included the line with a 0 center), which is i+1 away, you need to output through li inclusive

for(int j = l; j >= l-i; j--)
    System.out.print(j);

Right

The same loop as above, but reversed. Starts 1 higher because the center is already handled above and you don't want to output it again

for(int j = l-i+1; j <= l; j++)
    System.out.print(j);

Answer 2

I'd rework a little more than just that one line

    for (int j = 1; j <= (2 * i - 1); j++) {
        if((l-j) < l-i){
        // here System.out.print("*");
        }
        else
            System.out.print(l - j);

To...

for(int j = 1; j < i; j++)
     System.out.print(10-j);

System.out.println(10-i);

for(int j = 1; j < i; j++)
     System.out.print(10-i+j);    

Answer 3

This is completed program. I used "divide and conquer" method (basically the same idea as of Michael Mrozek), and use method to make it extreme-easy-to-understand program . Hope this will help.

public class PatternPrinter {
public static void main(String[] args) {
    printAllRows(9, 5);
}

public static void printAllRows(int max, int numOfRows) {
    for (int i = 1; i <= numOfRows; i++) {
        printRow(numOfRows - i, max, i);
        System.out.print("\n");
    }
}

public static void printRow(int numOfSpaces, int max, int num) {
    printSpaces(numOfSpaces);
    printLeftAndCenterPart(max, num);
    printRightPart(max, num - 1);
}

public static void printRightPart(int max, int num) {
    while(num > 0) {
        System.out.print(max - num + 1);
        num--;
    }
}

public static void printLeftAndCenterPart(int max, int num) {
    while(num > 0) {
        System.out.print(max--);
        num--;
    }
}

public static void printSpaces(int numOfSpaces) {
    while(numOfSpaces > 0) {
        System.out.print(" ");
        numOfSpaces--;
    }
}

}