Java: Set thousands separator in the said number

Last update on May 24 2025 12:58:57 (UTC/GMT +8 hours)

20. Add Thousand Separator

Write a Java program that takes a number and sets a thousand separators for 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:

Flowchart :

For more Practice: Solve these Related Problems:

• Write a Java program to format a number with commas as thousand separators using DecimalFormat.
• Write a Java program to manually insert thousand separators into an integer string using StringBuilder.
• Write a Java program to convert a large number into a locale-specific string with thousand separators.
• Write a Java program to implement a custom method that processes a numeric string and adds thousand separators.

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