Java text patterns

Generating text pattern is a regular requirement for students learning Java. Here I've written a collection of functions for you to try out.

import java.util.Arrays;

/**

 * @version 2022-Nov-15

 * @author azmeer

 * @see https://www.javatpoint.com/how-to-print-pattern-in-java

 * @see https://www.geeksforgeeks.org/printing-triangle-pattern-in-java/

 */

public class Patterns {

public static void square(String p) {

System.out.println("\nSquare Pattern");

int len = p.length();

for (int y = 0; y < len; y++) {

for (int x = 0; x < len; x++) {

System.out.print(p.charAt(x));

}

System.out.println();

}

}

public static void leftTriangleAsc(String p) {

System.out.println("\nLeft Triangle Ascending Pattern");

int len = p.length();

for (int y = 1; y <= len; y++) {

System.out.println(p.substring(0, y));

}

}

public static void leftTriangleDesc(String p) {

System.out.println("\nLeft Triangle Descending Pattern");

int len = p.length();

for (int y = len; y >= 1; y--) {

System.out.println(p.substring(0, y));

}

}

public static void rightTriangleAsc(String p) {

System.out.println("\nRight Triangle Ascending Pattern");

int len = p.length();

for (int y = 1; y <= len; y++) {

char[] spaces = new char[len - y];

Arrays.fill(spaces, ' ');

System.out.println(new String(spaces) + p.substring(0, y));

}

}

public static void rightTriangleDesc(String p) {

System.out.println("\nRight Triangle Descending Pattern");

int len = p.length();

for (int y = len; y >= 1; y--) {

char[] spaces = new char[len - y];

Arrays.fill(spaces, ' ');

System.out.println(new String(spaces) + p.substring(0, y));

}

}

public static void pyramid(String p) {

System.out.println("\nPyramid Pattern");

int len = p.length();

int i, j, row = len;

for (int y = 0; y < row; y++) {

for (j = row - y; j > 1; j--) {

System.out.print(" ");

}

for (j = 0; j <= y; j++) {

System.out.print("* ");

}

// throws the cursor in a new line after printing each line

System.out.println();

}

}

public static void bottomPyramid(String p) {

System.out.println("\nBottom Pyramid Pattern");

int rows = 8;

for (int i = 0; i <= rows - 1; i++) {

for (int j = 0; j <= i; j++) {

System.out.print(" ");

}

for (int k = 0; k <= rows - 1 - i; k++) {

System.out.print("*" + " ");

}

System.out.println();

}

}

public static void diamond(String p) {

System.out.println("\nDiamond Pattern");

int row, i, j, space = 1;

row = 10;

space = row - 1;

for (j = 1; j <= row; j++) {

for (i = 1; i <= space; i++) {

System.out.print(" ");

}

space--;

for (i = 1; i <= 2 * j - 1; i++) {

System.out.print("*");

}

System.out.println("");

}

space = 1;

for (j = 1; j <= row - 1; j++) {

for (i = 1; i <= space; i++) {

System.out.print(" ");

}

space++;

for (i = 1; i <= 2 * (row - j) - 1; i++) {

System.out.print("*");

}

System.out.println("");

}

}

public static void main(String[] args) {

String data = new String();

data = "0123456789";

System.out.println("Printing various triangles as string patterns \n");

square(data);

leftTriangleAsc(data);

leftTriangleDesc(data);

rightTriangleAsc(data);

rightTriangleDesc(data);

pyramid(data);

bottomPyramid(data);

diamond(data);

}

}