java代码打印一段菱形

Sure, here's one way to print a diamond pattern with Java code:

public static void printDiamond(int n) {
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n-i; j++) {
            System.out.print(" ");
        }
        for (int j = 1; j <= 2*i-1; j++) {
            System.out.print("*");
        }
        System.out.println();
    }
    for (int i = n-1; i >= 1; i--) {
        for (int j = 1; j <= n-i; j++) {
            System.out.print(" ");
        }
        for (int j = 1; j <= 2*i-1; j++) {
            System.out.print("*");
        }
        System.out.println();
    }
}

To use this code, you would call `printDiamond(n)` where `n` is the number of rows in the diamond (must be odd). The result will be printed to the console.