public class Test {

    public static void main(String[] args) {
        for(int i=1; i<=4; i++) {
            int j;
            for(j=1; j<=i; j++) {
                System.out.print(j + " ");
            }
            for(j=j-2; j>=1; j--) {
                System.out.print(j + " ");
            }
            System.out.println();
        }
    }
}

------解决方案--------------------
public class shishi {
	public static void main(String[] args) {
		getNum(1);
	}
	public static void getNum(int i){
			for(int j=1;j<=i;j++){
				for(int k=1;k<=(i-j)*2;k++){
					System.out.print(" ");
				}
				for(int h=1;h<=j;h++){
					System.out.print(h);
					System.out.print(" ");
				}
				for(int h=j-1;h>=1;h--){
					System.out.print(h);
					System.out.print(" ");
				}
				for(int k=1;k<=(i-j)*2;k++){
					System.out.print(" ");
				}
				System.out.println();
			}
		}
		

}
//我也是新手，总觉得我写的复杂了点，你看看能不能优化

------解决方案--------------------
Java code


public class Test {

    public static void main(String[] args) {
         for(int i=1; i<=4; i++) {
                int j;
                for(j=4;j>i;j--){
                    System.out.print("  ");
                }
                for(j=1; j<=i; j++) {
                    System.out.print(j + " ");
                }
                for(j=j-2; j>=1; j--) {
                    System.out.print(j + " ");
                }
                System.out.println();
            }

    }

}