Java Program to Convert Double to String

Last Updated : 25 Dec, 2023

The primary goal of double to String conversion in Java is to store big streams of numbers that are coming where even data types fail to store the stream of numbers. It is generically carried out when we want to display the bigger values. In this article, we will learn How to Convert double to String in Java.

Program to Convert double to String in Java

Below is the implementation of double to String conversion using ‘+’ :

Java

// Java Program to Convert
// Double to String Using '+'
import java.io.*;
 
// Driver Class
class GFG {
    // main function
    public static void main(String[] args)
    {
        // Double declared
        double num = 12.345;
 
        // Converting Double to String
        String str = num + "";
 
        System.out.println(str);
 
        // Type of num
        System.out.println(
            "Type of num : "
            + ((Object)num).getClass().getSimpleName());
 
        // Converted element to string
        System.out.println(
            "Type of str : "
            + ((Object)str).getClass().getSimpleName());
    }
}

Output

12.345
Type of num : Double
Type of str : String

Explaination of the above Program:

In above program we are converting num(Double) to String using ‘+’ Operator.

Different Methods for Converting double to String in Java

There are different kinds of methods to convert double data to string data. Two standard approaches are as follows:

Method	Class	Description	Syntax
valueOf() method	String	The valueOf() method simply typecasts below-given parameters to strings always as it is an inbuilt method of the String class in Java.	String valueOf(double num);
format() method	String	format() Method belongs to String and it uses precision modifier to convert double to string.	String.format(“%f”,variable_name)
append() Method from StringBuilder	String	append() Method from StringBuilder Class is used to append the element to the end of the StringBuilder Object.	String str= new StringBuilder().append(variable_name).toString();
toString() method	Decimal	In Java whenever a print is called, always toString() method of Object Class in Java is always called be it directly or indirectly. Even if this inbuilt function is not used and the double number is getting printed then too toString() method is called. The string is a class in Java.	Double.toString(var_name);
DecimalFormat	Decimal	DecimalFormat is a feature in Java in which we can format the decimal	DecimalFormat.getNumberInstance().format(var_name);

Example of Methods to Convert double to String in Java

Below is the implementation of Methods to Convert double to String:

Java

// Java Program to Convert
// Double Data to a String Data
 
// Importing Libraries
import java.io.*;
import java.text.DecimalFormat;
import java.util.*;
 
// Driver Class
class GFG {
    // Main driver function
    public static void main(String[] args)
    {
        // Declaring and initializing double number
        double number = 123.456;
 
        // Converting Double data to String data
        String method1 = String.valueOf(number);
        System.out.println("Using valueOf method "
                           + method1);
 
        // Conversion using format()
        String method2 = String.format("%f", number);
        System.out.println("Using format method "
                           + method2);
 
        // Conversion using append()
        String method3
            = new StringBuilder().append(number).toString();
        System.out.println("Using append method "
                           + method3);
 
        // Converting Double data to String data
        String method4 = Double.toString(number);
        System.out.println("Using toString method "
                           + method4);
 
        // Converting using DecimalFormat
        String method5
            = DecimalFormat.getNumberInstance().format(
                number);
        System.out.println("Using Decimalformat method "
                           + method5);
    }
}

Output

Using valueOf method 123.456
Using format method 123.456000
Using append method 123.456
Using toString method 123.456
Using Decimalformat method 123.456