How to convert String to Double in Java

In the last tutorial we learnt String to int conversion. In this tutorial we will see the String to Double conversion. There are three ways to convert a String into a double.

Method 1: Using Double.parseDouble

public static double parseDouble(String str) throws NumberFormatException

It returns the double value represented by the string argument and throws following exceptions:

NullPointerException – if the specified String str is null.
NumberFormatException – if the string format is not valid.  For e.g. If the string is “122.20ab” this exception will be thrown.

String str="122.202";
Double var= Double.parseDouble(str);

Double variable var value would be 122.202 after conversion.

Source: parseDouble JavaDoc

Method 2: Using Double.valueOf

String str3="122.202";
 Double var3= Double.valueOf(str3);

The value of var3 would be 122.202

Source: valueOf JavaDoc

Method 3: Double class constructor

String str2="122.202";
Double var2= new Double(str2);

Double class has a constructor which parses the passed String argument and returns a double value.

public Double(String s) throws NumberFormatException

Constructs a newly allocated Double object that represents the floating-point value of type double represented by the string. Source.

Complete Example:

public class Example{
   public static void main(String args[]){
       //Using parseDouble
       String str="122.202";
       Double var= Double.parseDouble(str);
       System.out.println(var);

       String str2="122.202";
       Double var2= new Double(str2);
       System.out.println(var2);

       //Using valueOf method
       String str3="122.202";
       Double var3= Double.valueOf(str3);
       System.out.println(var3);
   }
}

Output:

122.202
122.202
122.202