How to program in Java 8 Deitel & Deitel exercise triangule with stars

Triangulos.java

//Ejercicio 5.15
public class Triangulos {
	
	public static void main (String[] a) {
		//a
		for ( int i = 1 ; i <= 10; i++ ) {
			for ( int z=1; z<=i; z++) {
				System.out.print("*");
				
			}
			
			System.out.println();
		}
		
		System.out.println();
		//b
		for ( int i = 10 ; i >= 1; i-- ) {
			for ( int z=i; z>=1; z-- ) {
				System.out.print("*");
				
			}
			
			System.out.println();
		}
		
		System.out.println();
		
		//c
		String msg = "***********";
		for ( int i = 10 ; i >= 1; i-- ) {
			String newMsg = msg.substring(0, i);
			System.out.printf("%10s", newMsg);
			System.out.println();
		}
		System.out.println();
		//d
		for ( int i = 1 ; i <= 10; i++ ) {
			String newMsg = msg.substring(0, i);
			System.out.printf("%10s", newMsg);
			System.out.println();
		}
		/*
		System.out.printf("%10s%n","**********");
		System.out.printf("%10s%n","*********");
		System.out.printf("%10s%n","********");
		System.out.printf("%10s%n","*******");
		System.out.printf("%10s%n","******");
		System.out.printf("%10s%n","*****");
		System.out.printf("%10s%n","****");
		System.out.printf("%10s%n","***");
		System.out.printf("%10s%n","**");
		System.out.printf("%10s%n","*");
		
		*/
		
		System.out.println();
		
	}
}