Utility class for left pad, right pad, center pad and zero fill of strings in Java

StringPadding.java

package com.example;

/**
 * Utility class for left pad, right pad, center pad and zero fill.
 * 
 * @author Fabio Lima 2020-2021
 */
public final class StringPadding {

	public static String left(String string, int length, char fill) {

		if (string.length() < length) {

			char[] chars = string.toCharArray();
			char[] output = new char[length];

			int delta = length - chars.length;

			for (int i = 0; i < length; i++) {
				if (i < delta) {
					output[i] = fill;
				} else {
					output[i] = chars[i - delta];
				}
			}

			return new String(output);
		}

		return string;
	}

	public static String right(String string, int length, char fill) {

		if (string.length() < length) {

			char[] chars = string.toCharArray();
			char[] output = new char[length];

			for (int i = 0; i < length; i++) {
				if (i < chars.length) {
					output[i] = chars[i];
				} else {
					output[i] = fill;
				}
			}

			return new String(output);
		}

		return string;
	}

	public static String center(String string, int length, char fill) {

		if (string.length() < length) {

			char[] chars = string.toCharArray();

			int delta = length - chars.length;
			int a = (delta % 2 == 0) ? delta / 2 : delta / 2 + 1;
			int b = a + chars.length;

			char[] output = new char[length];
			for (int i = 0; i < length; i++) {
				if (i < a) {
					output[i] = fill;
				} else if (i < b) {
					output[i] = chars[i - a];
				} else {
					output[i] = fill;
				}
			}

			return new String(output);
		}

		return string;
	}

	public static String zerofill(String string, int length) {
		return left(string, length, '0');
	}

	private StringPadding() {
	}

	/**
	 * For tests!
	 */
	public static void main(String[] args) {

		String string = "123";
		char blank = ' ';

		System.out.println("left pad:    [" + StringPadding.left(string, 10, blank) + "]");
		System.out.println("right pad:   [" + StringPadding.right(string, 10, blank) + "]");
		System.out.println("center pad:  [" + StringPadding.center(string, 10, blank) + "]");
		System.out.println("zero fill:   [" + StringPadding.zerofill(string, 10) + "]");
	}
}

/**
 * OUTPUT
 * 
 * left pad:    [       123]
 * right pad:   [123       ]
 * center pad:  [    123   ]
 * zero fill:   [0000000123]
 * 
 */