Java Convert String to Double examples

In the last tutorial we learned String to int conversion. In this guide we will see how to convert String to Double in Java. There are three ways to convert String to double.

Method 1: Java Convert String to Double using Double.parseDouble(String)

public static double parseDouble(String str) throws NumberFormatException

This method returns the double representation of the passed String argument. This method throws NullPointerException, if the specified String str is null and NumberFormatException – if the string format is not valid.  For example, if the string is “122.20ab” this method would throw NumberFormatException.

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

The value of variable “var” of double type would be 122.202 after conversion.

Lets see the complete example of the conversion using parseDouble(String) method.

Example 1: Java Program to convert String to double using parseDouble(String)

public class Example{
   public static void main(String args[]){
	String str="122.202";

	/* using parseDouble(String) method to
	 * convert String to double
	 */
	double var= Double.parseDouble(str);
	System.out.println(var);
   }
}

Output:

122.202

Method 2: Java Convert String to Double using Double.valueOf(String)

String str2 = "122.111";
double var2 = Double.valueOf(str2);

The value of var2 would be 122.111 after conversion

Lets see the complete example of conversion using Double.valueOf(String) method.

Example 2: Java Program to convert String to double using valueOf(String)

public class Example{
   public static void main(String args[]){
	String str2 = "122.111";
	double var2 = Double.valueOf(str2);
	System.out.println(var2);
   }
}

Output:

122.111

Method 3: Java Convert String to double using the constructor of Double class

String str3 = "999.333";
double var3 = new Double(str3);

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

public Double(String s) throws NumberFormatException

Using this constructor we can create a new object of the Double class by passing the String that we want to convert.

Example 3: Java Program to convert String to double using the constructor of Double class

In this example we are creating an object of Double class to convert the String value to double value.

public class Example{
   public static void main(String args[]){
       String str3 ="999.333";
       double var3 = new Double(str3);
       System.out.println(var3);
   }
}

Output:

999.333

Related Posts:

1. Java – Convert String to Long
2. Java – Convert double to String
3. Java – Convert int to String
4. Java – Convert float to String
5. Java – Convert boolean to String

References:

• parseDouble(String) JavaDoc
• Double.valueOf(String) JavaDoc
• new Double(String) JavaDoc