Java Convert double to String

Let’s look at different code snippets for java double to string conversion. Note that double is a primitive data type whereas Double is an Object. However java supports autoboxing, so they both can be used interchangeably in most of the cases.

1. Using + operator

   This is the easiest way to convert double to string in java.

   double d = 123.45d;
   String str = d+""; // str is '123.45'
   

2. Double.toString()

   We can use Double class toString method to get the string representation of double in decimal points. Below code snippet shows you how to use it to convert double to string in java.

   double d = 123.45d;
   String str = Double.toString(d);
   System.out.println(str); //prints '123.45'
   

3. String.valueOf()

   double d = 123.456d;
   String str = String.valueOf(d); // str is '123.456'
   

4. new Double(double l)

   Double constructor with double argument has been deprecated in Java 9, but you should know it.

   double d = 123.45d;
   //deprecated from Java 9, use valueOf for better performance
   String str = new Double(d).toString();
   System.out.println(str);
   

5. String.format()

   We can use Java String format method to convert double to String in our programs.

   double d = 36.98d;
   String s = String.format("%f", d);
   System.out.println(s); //36.980000
   

6. DecimalFormat

   We can use DecimalFormat class to convert double to String. We can also get string representation with specified decimal places and rounding of half-up.

   double d = 123.454d;
   String str = DecimalFormat.getNumberInstance().format(d);
   System.out.println(str); //str is '123.454'
   //if you don't want formatting
   str = new DecimalFormat("#.0#").format(d); // rounded to 2 decimal places
   System.out.println(str); //str is '123.45'
   str = new DecimalFormat("#.0#").format(123.456); // rounded to 2 decimal places
   System.out.println(str); //str is '123.46'
   

7. StringBuilder, StringBuffer

   We can use StringBuilder and StringBuffer append function to convert double to string.

   double d = 123.45d;
   String str = new StringBuilder().append(d).toString();
   

Here is a simple program where we will convert double to string and print it using all the different methods we saw above.

package com.journaldev.string;

import java.text.DecimalFormat;

public class JavaDoubleToString {

	public static void main(String[] args) {
		double d = 123.45d;
		String str = Double.toString(d);
		System.out.println(str);

		str = String.valueOf(d);
		System.out.println(str);

		// deprecated from Java 9, use valueOf for better performance
		str = new Double(d).toString();
		System.out.println(str);

		str = String.format("%f", d);
		System.out.println(str); //123.450000

		str = d + "";
		System.out.println(str);

		str = DecimalFormat.getNumberInstance().format(d);
		System.out.println(str);

		str = new DecimalFormat("#.0#").format(d);
		System.out.println(str);

		str = new StringBuilder().append(d).toString();
		System.out.println(str);
	}

}

That’s all for converting double to string in java program. Reference: Double API Doc