Java Program to Convert String to Double

In this Java program, we will learn to convert the String variables to a double value using several different methods.

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Using Double.parseDouble() method

String str = "42.5";
double d = Double.parseDouble(str);

This method takes a String as an argument and returns the equivalent double representation. If the string is not a valid double representation, it will throw NumberFormatException.

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Using Double.valueOf() method

String str = "42.5";
double d = Double.valueOf(str);

This method also takes a String as an argument and returns a Double object that contains the double value represented by the string. It throws NumberFormatException if the string is not a valid double representation.

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Using DecimalFormat class

String str = "42.5";
DecimalFormat df = new DecimalFormat();
double d = df.parse(str).doubleValue();

This method uses the DecimalFormat class to parse the string and returns the double value represented by the string.

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Java Program to Convert String to Double

public class StringToDoubleExample {
  public static void main(String[] args) {
    String str = "42.5";

    // Using Double.parseDouble() method
    try {
      double d1 = Double.parseDouble(str);
      System.out.println("Double.parseDouble(): " + d1);
    } catch (NumberFormatException e) {
      System.out.println("The string is not a valid double");
    }

    // Using Double.valueOf() method
    try {
      double d2 = Double.valueOf(str);
      System.out.println("Double.valueOf(): " + d2);
    } catch (NumberFormatException e) {
      System.out.println("The string is not a valid double");
    }

    // Using DecimalFormat class
    try {
      DecimalFormat df = new DecimalFormat();
      double d3 = df.parse(str).doubleValue();
      System.out.println("DecimalFormat: " + d3);
    } catch (ParseException e) {
      System.out.println("The string is not a valid double");
    }
  }
}

Output

Double.parseDouble(): 42.5
Double.valueOf(): 42.5
DecimalFormat: 42.5

This program defines a String variable str with the value "42.5". Then, it demonstrates the use of the Double.parseDouble() method, the Double.valueOf() method, and the DecimalFormat class for converting the String to a double.

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