How to Convert String to Double in Java

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Rupam Yadav Feb 02, 2024
Java Java Double Java String
  1. Double.parseDouble() Method to Convert a String to a Double
  2. Double.valueOf() Method to Convert a String to a Double
  3. DecimalFormat.parse to Convert a String to a Double
  4. Handle NumberFormatException While Converting a String Value to a Double Value
How to Convert String to Double in Java

We will introduce different ways to convert the given string into a double in Java with some easy to understand examples.

Double.parseDouble() Method to Convert a String to a Double

The best and easiest way to cast a string to double in Java is by using the static method parseDouble of the class Double.

Double.parseDouble returns a primitive type.

public class Main {
  public static void main(String[] args) {
    String stringValue = "12.34";

    double doubleValue = Double.parseDouble(stringValue);
    System.out.println("Converted value: " + doubleValue);
  }
}

Output:

Converted value: 12.34

It can be a negative or positive value in the string; this method will parse string to double correctly.

public class Main {
  public static void main(String[] args) {
    String stringValueNegative = "-12.34";
    String stringValuePositive = "+12.34";
    double doubleValueNegative = Double.parseDouble(stringValueNegative);
    double doubleValuePositive = Double.parseDouble(stringValuePositive);

    System.out.println("Converted negative value: " + doubleValueNegative);
    System.out.println("Converted positive value: " + doubleValuePositive);
  }
}

Output:

Converted negative value: -12.34
Converted positive value: 12.34

Double.valueOf() Method to Convert a String to a Double

When we need a Double object instead of a primitive type double, we can use the Double.valueOf method to get a double object value from a string.

public class Main {
  public static void main(String[] args) {
    String stringValueNegative = "-12.08d";
    String stringValuePositive = "+12.3400";

    Double doubleValueNegative = Double.valueOf(stringValueNegative);
    Double doubleValuePositive = Double.valueOf(stringValuePositive);
    System.out.println(doubleValueNegative);
    System.out.println(doubleValuePositive);
  }
}

Output:

-12.08
12.34

DecimalFormat.parse to Convert a String to a Double

If the value we desire is something like 1,11,111.12d, we can use the DecimalFormat class to parse the string to a doubleValue().

But as the DecimalFormat class can return different values like int or byte, it is necessary to do all the operations in the try-catch block. And as we desire a doubleValue, we have to use the doubleValue() method to definitively get the double type.

import java.text.DecimalFormat;
import java.text.ParseException;

public class Main {
  public static void main(String[] args) {
    String stringValue = "1,11,111.12d";

    try {
      double doubleValue = DecimalFormat.getNumberInstance().parse(stringValue).doubleValue();
      System.out.println(doubleValue);

    } catch (ParseException e) {
      e.printStackTrace();
    }
  }
}

Output:

111111.12

Handle NumberFormatException While Converting a String Value to a Double Value

Sometimes we might get NumberFormatException. It happens because the string value is not a valid double value.

To make it more clear, we will see a simple example which throws this exception.

public class Main {
  public static void main(String[] args) {}
  String stringValue = "1,11";

  double d = Double.parseDouble(stringValue);
  System.out.println(d);
}
}

Output:

Exception in thread "main" java.lang.NumberFormatException: For input string: "1,11"
	at java.base/jdk.internal.math.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:2054)
	at java.base/jdk.internal.math.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
	at java.base/java.lang.Double.parseDouble(Double.java:543)
	at com.company.Main.main(Main.java:14)

The exception happens because 1,11 is not a valid double value. The solution for this error is to replace comma with a decimal point like we are doing below.

public class Main {
  public static void main(String[] args) {
    String stringValue = "1,11";

    double d = Double.parseDouble(stringValue.replace(",", "."));
    System.out.println(d);
  }
}

Output:

1.11
Author: Rupam Yadav
Rupam Yadav avatar Rupam Yadav avatar

Rupam Saini is an android developer, who also works sometimes as a web developer., He likes to read books and write about various things.

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