Pyramid.java

package com.silan;
import java.util.Collections;
public class  Pyramid {
public static void main(String[] args) { 
	int rows = 5; 
	System.out.println("\n1. Half Pyramid\n");
	for (int i = 0; i < rows; i++) { 
		for (int j = 0; j <= i; j++) {
			System.out.print("*");
		}
		System.out.println("");
	} 
	System.out.println("\n2. Full Pyramid\n");
	for (int i = 0; i < rows; i++) { 
		for (int j = 0; j < rows - i; j++) {
			System.out.print(" "); 
		}
		for (int k = 0; k <= i; k++) {
			System.out.print("* ");
		} 
		System.out.println("");  //java 8 , one line
		 
		System.out.println("\n3. Full Pyramid (Compact)\n");
		for (int i = 0; i < rows; i++) {
			System.out.println(String.join("", Collections.nCopies(5 - i - 1, " ")) +
				String.join("", Collections.nCopies(2 * i + 1, "*")));
		}  // java 8
		 
		System.out.println("\n4. Inverted Pyramid\n"); 
		for (int i = rows; i > 0; i--) { 
			System.out.println(String.join("", Collections.nCopies(5 - i, " ")) +
				String.join("", Collections.nCopies(2 * i - 1, "*")));
		} 
	}
}

Output

1. Half Pyramid

*
**
***
****
*****

2. Full Pyramid

     *
    * *
   * * *
  * * * *
 * * * * *

3. Full Pyramid (Compact)

    *
   ***
  *****
 *******
*********

4. Inverted Pyramid

*********
 *******
  *****
   ***
    *