Regular Expression for Match, Negation, Range, Union, Intersection and Subtraction

Matching Character with Regular Expression in Java is very easy.

Sample Java program to perform:

• Match
• Ignore
• Match in given range
• Union match
• Intersection match
• Subtraction match

package com.learning.regex;

public class RegexCharacterMain {

	public static void main(String[] args) {

		matchAnyGivenCharacter();

		ignoreAllGivenCharacter();
		
		matchCharacterRange();
		
		unionMatchWithRange();

		intersectionMatch();
		
		subtractionMatch();
	}

	private static void matchAnyGivenCharacter() {

		System.out.println("\n**************** matchAnyGivenCharacter *****************\n");
		
		String regExPattern = "[abc]"; // matches a or b or c

		String inputString = "b";

		Boolean result = inputString.matches(regExPattern);

		if (result) {
			System.out.println(inputString + " : Character Match Found using Regular Expression " + regExPattern);
		} else {
			System.out.println(inputString + " : Character Match NOT Found using Regular Expression " + regExPattern);
		}
	}

	private static void ignoreAllGivenCharacter() {
		
		System.out.println("\n**************** ignoreInGivenCharacter *****************\n");
		
		String regExPattern = "[^abc]"; // Ignore only a, b or c

		String inputString = "a";

		Boolean result = inputString.matches(regExPattern);

		if (result) {
			System.out.println(inputString + " : NOT Ignored in Regular Expression " + regExPattern);
		} else {
			System.out.println(inputString + " : Ignored in Regular Expression " + regExPattern);
		}

	}

	
	private static void matchCharacterRange() {
		
		System.out.println("\n**************** matchCharacterRange *****************\n");
		
		String regExPattern = "[a-c]"; // Range, to match a, b or c

		String inputString = "b";

		Boolean result = inputString.matches(regExPattern);

		if (result) {
			System.out.println(inputString + " : Found in Range Regular Expression " + regExPattern);
		} else {
			System.out.println(inputString + " : NOT Found in Range Regular Expression " + regExPattern);
		}

	}
	
	
	private static void unionMatchWithRange() {
		
		System.out.println("\n**************** unionMatchWithRange *****************\n");
		
		String regExPattern = "[a-c[f-h]]"; // Union, to match a, b, c, f, g, h

		String inputString = "g";

		Boolean result = inputString.matches(regExPattern);

		if (result) {
			System.out.println(inputString + " : Found in Union-Range Regular Expression " + regExPattern);
		} else {
			System.out.println(inputString + " : NOT Found in Union-Range Regular Expression " + regExPattern);
		}

	}
	
	private static void intersectionMatch() {
		
		System.out.println("\n**************** intersectionMatch *****************\n");
		
		String regExPattern = "[a-c&&[b-c]]"; // intersection, to match b or c

		String inputString = "c";

		Boolean result = inputString.matches(regExPattern);

		if (result) {
			System.out.println(inputString + " : Found in intersection Regular Expression " + regExPattern);
		} else {
			System.out.println(inputString + " : NOT Found in intersection Regular Expression " + regExPattern);
		}

	}

	private static void subtractionMatch() {
		
		System.out.println("\n**************** subtractionMatch *****************\n");
		
		String regExPattern = "[a-c&&[^b-c]]"; // Subtraction, to match a only

		String inputString = "c";

		Boolean result = inputString.matches(regExPattern);

		if (result) {
			System.out.println(inputString + " : Found in subtraction Regular Expression " + regExPattern);
		} else {
			System.out.println(inputString + " : NOT Found in subtraction Regular Expression " + regExPattern);
		}

	}
}

Sample Java program output:

**************** matchAnyGivenCharacter *****************

b : Character Match Found using Regular Expression [abc]

**************** ignoreInGivenCharacter *****************

a : Ignored in Regular Expression [^abc]

**************** matchCharacterRange *****************

b : Found in Range Regular Expression [a-c]

**************** unionMatchWithRange *****************

g : Found in Union-Range Regular Expression [a-c[f-h]]

**************** intersectionMatch *****************

c : Found in intersection Regular Expression [a-c&&[b-c]]

**************** subtractionMatch *****************

c : NOT Found in subtraction Regular Expression [a-c&&[^b-c]]