In Java, converting a double value to its equivalent String representation is a common operation, especially when dealing with data manipulation and output formatting. Java provides various methods to convert a double to a String. In this blog post, we will explore different techniques with examples.

1. Using Double.toString() Method

The Double.toString() method is the simplest way to convert a double value to its String representation. It returns a String that contains the decimal representation of the double value.

Example:

public class DoubleToStringExample {
    public static void main(String[] args) {
        double doubleValue = 123.45;
        String stringValue = Double.toString(doubleValue);

        System.out.println("Double Value: " + doubleValue);
        System.out.println("String Value: " + stringValue);
    }
}

Output:

Double Value: 123.45
String Value: 123.45

2. Using String.format() Method

Similar to converting a float, the String.format() method can be used to create a formatted String representation of a double value with desired precision.

Example:

public class DoubleToStringExample {
    public static void main(String[] args) {
        double doubleValue = 67.89678;
        String stringValue = String.format("%.2f", doubleValue);

        System.out.println("Double Value: " + doubleValue);
        System.out.println("String Value: " + stringValue);
    }
}

Output:

Double Value: 67.89678
String Value: 67.90

3. Using DecimalFormat Class

Just like converting a float, you can use the DecimalFormat class to format a double value as a string with more control over the formatting options.

Example:

import java.text.DecimalFormat;

public class DoubleToStringExample {
    public static void main(String[] args) {
        double doubleValue = 9876.54321;

        DecimalFormat decimalFormat = new DecimalFormat("#,##0.00");
        String stringValue = decimalFormat.format(doubleValue);

        System.out.println("Double Value: " + doubleValue);
        System.out.println("String Value: " + stringValue);
    }
}

Output:

Double Value: 9876.54321
String Value: 9,876.54

Conclusion

Converting a double to a String is a common operation in Java, and you have several methods at your disposal. The Double.toString() method is the most straightforward approach, while the String.format() method and DecimalFormat class offer more advanced formatting options.