java源代碼：

package studying;

/*
 * Print Diamond
 */

public class PrintDiamond {

    public static void main(String[] args) {

        //Upper part
        for(int m = 1; m <= 10; m++) {
            
            //Output Spaces
            for(int n = 9; n >= m; n--) {
                System.out.print(
 
" ");
            }
            
            //Output * Upper Left
            for(int n = 1; n <= m; n++) {
                System.out.print("*");
            }
            
            //Output * Upper Right
            for(int n = 1; n < m; n++) {
                System.out.print("*");
            }
            System.out.println();
        }
        
        
        
 
//Second half
        for(int m = 1; m <= 9; m++) {
            
            //output spaces
            for(int n = 1; n<=m; n++) {
                System.out.print(" ");
            }
            
            //Output * Lower left
            for(int n = 9; n >= m; n--) {
                System.out.print(
 
"*");
            }
            
            //Output * Lower right
            for(int n = 9; n > m; n--) {
                System.out.print("*");
            }
            System.out.println();
        }

    }

}

結果展示：

java--輸出一個菱形