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Java programming Exercises: Set thousands separator in the said number

Java Regular Expression: Exercise-20 with Solution

Write a Java program that takes a number and set thousands separator in that number.

Sample Solution:

Java Code:

import java.text.NumberFormat;
import java.util.Locale;
import java.text.Format;

public class test {
 
   public static void main(String[] args) {	   
	    int n = 100;
		System.out.println("Original Number: "+n);
		System.out.println("Set thousands separator in the said number): "+validate(n));
	    n = 1000;
		System.out.println("\nOriginal Number: "+n);
		System.out.println("Set thousands separator in the said number): "+validate(n));
	    n = 10000;
		System.out.println("\nOriginal Number: "+n);
		System.out.println("Set thousands separator in the said number): "+validate(n));	
	    n = 100000;
		System.out.println("\nOriginal Number: "+n);
		System.out.println("Set thousands separator in the said number): "+validate(n));		
	    n = 1000000;
		System.out.println("\nOriginal Number: "+n);
		System.out.println("Set thousands separator in the said number): "+validate(n));		
		    		    
        }

   public static String validate(int n) {
		String num = Integer.toString(n);
		int len = num.length();
		if(len < 4) {
			return num;
		}
		//You can use any character as separator 
		return validate(Integer.parseInt(num.substring(0, len-3))) + '#' + num.substring(len-3);
   }
}

Sample Output:

Original Number: 100
Set thousands separator in the said number): 100

Original Number: 1000
Set thousands separator in the said number): 1#000

Original Number: 10000
Set thousands separator in the said number): 10#000

Original Number: 100000
Set thousands separator in the said number): 100#000

Original Number: 1000000
Set thousands separator in the said number): 1#000#000

Pictorial Presentation:

Java Regular Expression: Set thousands separator in the said number.

Flowchart :

Flowchart: Set thousands separator in the said number.

Java Code Editor:

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Previous: Remove the specific letters from a string and return the new string.

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

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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