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Java programming Exercises: Remove all non-alphanumeric characters from a given string

Java Regular Expression: Exercise-21 with Solution

Write a Java program to remove all non-alphanumeric characters from a given string.

Sample Solution-1:

Java Code:

public class test {
 
   public static void main(String[] args) {	   
	    String text ="Java Exercises";
		System.out.println("Original string: "+text);
		System.out.println("After removing all non-alphanumeric characters from the said string: "+validate(text));
	    text ="[email protected]^%&%(ercis*&)&es";
		System.out.println("\nOriginal string: "+text);
		System.out.println("After removing all non-alphanumeric characters from the said string: "+validate(text));	
        }

   public static String validate(String text) {
        return text.replaceAll("(?i)[^A-Z]", "");
   }
}

Sample Output: 

Original string: Java Exercises
After removing all non-alphanumeric characters from the said string: JavaExercises

Original string: [email protected]^%&%(ercis*&)&es
After removing all non-alphanumeric characters from the said string: Exercises

Pictorial Presentation:

Java Regular Expression: Remove all non-alphanumeric characters from a given string.

Flowchart :

Flowchart: Remove all non-alphanumeric characters from a given string.

Sample Solution-2:

Java Code:

public class test {
 
   public static void main(String[] args) {	   
	    String text ="Java Exercises";
		System.out.println("Original string: "+text);
		System.out.println("After removing all non-alphanumeric characters from the said string: "+validate(text));
	    text ="[email protected]^%&%(ercis*&)&es";
		System.out.println("\nOriginal string: "+text);
		System.out.println("After removing all non-alphanumeric characters from the said string: "+validate(text));	
        }

   public static String validate(String text) {
        return text.replaceAll("[^a-zA-Z]", "");
   }
}

Sample Output: 

Original string: Java Exercises
After removing all non-alphanumeric characters from the said string: JavaExercises

Original string: [email protected]^%&%(ercis*&)&es
After removing all non-alphanumeric characters from the said string: Exercises

Flowchart :

Flowchart: Remove all non-alphanumeric characters from a given string.

Java Code Editor:

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Java: Tips of the Day

What is the best way to filter a Java Collection?

Java 8 (2014) solves this problem using streams and lambdas in one line of code:

List<Person> beerDrinkers = persons.stream()
    .filter(p -> p.getAge() > 16).collect(Collectors.toList());

Use Collection#removeIf to modify the collection in place. (Notice: In this case, the predicate will remove objects who satisfy the predicate):

persons.removeIf(p -> p.getAge() <= 16);

lambdaj allows filtering collections without writing loops or inner classes:

List beerDrinkers = select(persons, having(on(Person.class).getAge(),
    greaterThan(16)));

Ref: https://bit.ly/3uwYid6