MainClass.java

package core_java_exercises;

import java.util.*;

class HolderClass extends MainClass {

	public void pattern2Template(int n2) { 	// template function used in draw2 and draw3
		for (int i = n2; i >= 1; i--) { 	// Row for loop
			if (i % 2 != 0) { 	// condition to check only odd no. of rows must get printed
				for (int j = 1; j < i; j++) { 	// White space for loop
					System.out.print(" ");
				}
				for (int z = n2; z >= i; z--) { 	// Star for loop
					System.out.print("* ");
				}
				System.out.println();
			}
		}
	}

	public void draw1(int n1) {
		for (int i = n1; i >= 1; i--) { 	// Row for loop
			if (i % 2 != 0) { 	// condition to check only odd no. of rows must get printed
				for (int j = n1; j > i; j--) { 	// White space for loop
					System.out.print(" ");
				}
				for (int z = i; z >= 1; z--) { 	// Star for loop
					System.out.print("* ");
				}
				System.out.println();
			}
		}
		System.out.println("\n");
		main(null);
	}

	public void draw2(int n2) {
		pattern2Template(n2);	 // calling template function
		System.out.println("\n");
		main(null);
	}

	public void draw3(int n3) {
		for (int i = (n3 - 1); i >= 1; i--) { 	// Row for loop
			if (i % 2 != 0) { 	// condition to check only odd no. of rows must get printed
				for (int j = n3; j > i; j--) { 	// White space for loop
					System.out.print(" ");
				}
				for (int z = i; z >= 1; z--) { 	// Star for loop
					System.out.print("* ");
				}
				System.out.println();
			}
		}
		System.out.println("\n");
		main(null);
	}

	public void draw4(int n4) {
		for (int i = 0; i <= (n4 / 2) + 1; i++) { 	// upper triangle
			for (int j = 1; j <= i; j++) {
				System.out.print("* ");
			}
			System.out.println();
		}
		for (int i = (n4 / 2); i >= 0; i--) { 	// lower triangle
			for (int j = 1; j <= i; j++) {
				System.out.print("* ");
			}
			System.out.println();
		}
		System.out.println("\n");
		main(null);

	}

	public void draw5(int n5) {
		for (int i = 1; i <= (n5 / 2) + 1; i++) { 	// upper triangle
			for (int j = (n5 / 2); j >= i; j--) {
				System.out.print("  ");
			}
			for (int k = 1; k <= i; k++) {
				System.out.print("* ");
			}
			System.out.println();
		}
		for (int i = 1; i <= (n5 / 2) + 1; i++) { 	// upper triangle
			for (int j = 1; j <= i; j++) {
				System.out.print("  ");
			}
			for (int z = (n5 / 2); z >= i; z--) {
				System.out.print("* ");
			}
			System.out.println();
		}
		System.out.println("\n");
		main(null);
	}

}

public class MainClass {

	public static void main(String[] args) {

		HolderClass obj = new HolderClass();

		System.out.println("Please enter Function number [from 1-6] " + "\n 1. Reverse Isosceles Triangle "
				+ "\n 2. Regular Isosceles Triangle" + "\n 3. Kite shape pattern" + "\n 4. Left Base Triangle"
				+ "\n 5. Right Base Triangle" + "\n 6. Quit");
		Scanner sc = new Scanner(System.in);
		int choice = sc.nextInt();

		// Switch - case to select pattern number.

		switch (choice) {
		case 1:
			System.out.println("You have selected Reverse Isosceles Triangle, Please Enter an odd number");
			int n1 = sc.nextInt();
			oddCheck(n1);
			obj.draw1(n1);
			break;
		case 2:
			System.out.println("You have selected Regular Isosceles Triangle, Please Enter an odd number");
			int n2 = sc.nextInt();
			oddCheck(n2);
			obj.draw2(n2);
			break;
		case 3:
			System.out.println("You have selected Kite shape pattern, Please Enter an odd number");
			int n3 = sc.nextInt();
			oddCheck(n3);
			obj.pattern2Template(n3); 	// Reusing pattern2_temp
			obj.draw3(n3);
			break;
		case 4:
			System.out.println("You have selected Left Base Triangle, Please Enter an odd number");
			int n4 = sc.nextInt();
			oddCheck(n4);
			obj.draw4(n4);
			break;
		case 5:
			System.out.println("You have selected Right Base Triangle, Please Enter an odd number");
			int n5 = sc.nextInt();
			oddCheck(n5);
			obj.draw5(n5);
			break;
		case 6:
			System.out.print("------------------------------Thank you!------------------------------");
			break;
		default:
			System.out.println("\n\n ||| Please enter valid input ||| \n\n");
			main(null);
			break;
		}
	}

	public static void oddCheck(int num) {
		if (num % 2 == 0) {
			System.out.println("\n ------------------------------Please enter an Odd number------------------------------ \n");
			main(null);
		}
	}

}