Java: Count the number of decimal places in a given number

Last update on May 24 2025 12:59:00 (UTC/GMT +8 hours)

17. Count Decimal Places

Write a Java program to count the number of decimal places in a given number.

Sample Solution-1:

Java Code:

public class test {
 
   public static void main(String[] args) {	   
	   String n = "123";
	   System.out.println("Original Number: "+n);
	   System.out.println("Number of decimal places in the said number: "+validate(n));
	   n = "112.3";
    	   System.out.println("\nOriginal Number: "+n);
	   System.out.println("Number of decimal places in the said number: "+validate(n));
	   n = "112.03";
    	  System.out.println("\nOriginal Number: "+n);
	  System.out.println("Number of decimal places in the said number: "+validate(n));
	  n = "112.233";
    	 System.out.println("\nOriginal Number: "+n);
	 System.out.println("Number of decimal places in the said number: "+validate(n));
        }

   public static Integer validate(String n) {
	   	if(n.contains("."))
			return n.replaceAll(".*\\.(?=\\d?)", "").length();
		return 0;
  }
}

Sample Output:

Original Number: 123
Number of decimal places in the said number: 0

Original Number: 112.3
Number of decimal places in the said number: 1

Original Number: 112.03
Number of decimal places in the said number: 2

Original Number: 112.233
Number of decimal places in the said number: 3

Pictorial Presentation:

Flowchart :

Sample Solution-2:

Java Code:

public class test {
 
   public static void main(String[] args) {	   
	    String n = "123";
		System.out.println("Original Number: "+n);
		System.out.println("Number of decimal places in the said number: "+validate(n));
		n = "112.3";
    	System.out.println("\nOriginal Number: "+n);
		System.out.println("Number of decimal places in the said number: "+validate(n));
		n = "112.03";
    	System.out.println("\nOriginal Number: "+n);
		System.out.println("Number of decimal places in the said number: "+validate(n));
		n = "112.233";
    	System.out.println("\nOriginal Number: "+n);
		System.out.println("Number of decimal places in the said number: "+validate(n));
        }

   public static Integer validate(String n) {
	   	int ctr = n.indexOf(".");
		return ctr > 0 ? n.length() - ctr - 1 : 0;
  }
}

Sample Output:

Original Number: 123
Number of decimal places in the said number: 0

Original Number: 112.3
Number of decimal places in the said number: 1

Original Number: 112.03
Number of decimal places in the said number: 2

Original Number: 112.233
Number of decimal places in the said number: 3

Flowchart :

For more Practice: Solve these Related Problems:

• Write a Java program to determine the number of digits after the decimal point in a floating-point number represented as a string.
• Write a Java program to count the fractional digits in a decimal number by splitting its string representation.
• Write a Java program to implement a method that returns the number of decimal places in a number, handling cases with no decimal point.
• Write a Java program to compare the decimal precision of two numbers by counting their decimal places.

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