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Java programming Exercises: Find sequences of lowercase letters joined with a underscore

Java Regular Expression: Exercise-3 with Solution

Write a Java program to find sequences of lowercase letters joined with a underscore.

Sample Solution:

Java Code:

import java.util.Scanner;
public class test {
 
   public static void main(String[] args) {
	   
	    System.out.println(validate("java_exercises"));
		System.out.println(validate("Java_exercises"));
		System.out.println(validate("java_Exercises"));		
		System.out.println(validate("Java_Exercises"));	
        }

   public static String validate(String text) {
	   if (text.matches("^[a-z]+_[a-z]+$"))
                return "Found a match!";
       else
                return "Not matched!";
   }
}

Sample Output: 

Found a match!
Not matched!
Not matched!
Not matched!

Pictorial Presentation:

Java Regular Expression: Find sequences of lowercase letters joined with a underscore.
Java Regular Expression: Find sequences of lowercase letters joined with a underscore.

Flowchart :

Flowchart: Find sequences of lowercase letters joined with a underscore.

Java Code Editor:

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Next: Find the sequences of one upper case letter followed by lower case letters.

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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