Java Double To String 2 Decimal Places Examples

Oct 20, 2016 Core Java, Examples, Snippet, String comments

When dealing with double values in your application, it is sometimes required to convert the values into String. Below are examples on how to convert double to String in Java using two decimal places.

Convert using String.format()

When using Java 5 or above, String.format() method can be used to convert a double to a String value. Below is the example applied to 2 decimal places:

/**
 * A simple Java example that converts a double to String using two decimal places via String.format().
 */
public class Test {
    public static void main(String[] args) {
        double number = 123.4567d;
        String numberAsString = String.format ("%.2f", number);
        System.out.println(numberAsString);
    }
}

The parameter "%.2f" tells the formatter to use specifically two decimal places. When we run this, since there are more than 2 decimal places, it will be rounded. Hence the .45 will be .46 and the output will be:

123.46

If we want to format using two decimal places and also separate thousands indicator using comma, we can do this also using String.format() method. Here is an example:

/**
 * A simple Java example that converts a double to String using two decimal places and using comma 
 * as thousand separator via String.format().
 */
public class Test {
    public static void main(String[] args) {
        double number = 189563245.4567d;
        String numberAsString = String.format ("%,.2f", number);
        System.out.println(numberAsString);
    }
}

The parameter "%,.2f" tells to use comma as thousand separator and 2 decimal digit when converting. The whole number is therefore comma separated for every 3 digits from the right. And the decimal digits are capped to two decimal places and rounding if necessary. Below is the output of the code:

189,563,245.46

Convert using DecimalFormat

We can also use the java.text.DecimalFormat class that can format a number into a String following a given pattern. Below is an examples on how to convert a double into string using two decimal places and utilizing DecimalFormat class:

/**
 * A simple Java example that converts a double to String using two decimal places via DecimalFormat.
 */
public class Test {
    public static void main(String[] args) {
        double number = 456.7891d;
        DecimalFormat decimalFormat = new DecimalFormat("#.00");
        String numberAsString = decimalFormat.format(number);
        System.out.println(numberAsString);
    }
}

The ".00" in the parameter tells the formatter to use two decimal places while the "#" means to display the whole number as it is. The output is also rounded, which should be:

456.79

Similar to the previous method, we can also use DecimalFormat to also do thousand separator. Below is an example on how to do that using DecimalFormat:

/**
 * A simple Java example that converts a double to String using two decimal places and using comma 
 * as thousand separator via DecimalFormat.
 */
public class Test {
    public static void main(String[] args) {
        double number = 12345678.7891d;
        DecimalFormat decimalFormat = new DecimalFormat("#,##0.00");
        String numberAsString = decimalFormat.format(number);
        System.out.println(numberAsString);
    }
}

Whole numbers are comma separated every three digit and the decimal place is rounded to two decimal. The output therefore is:

12,345,678.79