Java - Double

Java Conceptuel Diagram


Double in Java

They implements the 64-bit precision IEEE 754 floating point

Documentation: javase/9/docs/api/java/lang/Double.html

Double is a subtype of number.

Instance Creation

  • Literal
Double d = 1D;



public static double round(double value, int places) {
        if (places < 0) throw new IllegalArgumentException();

        BigDecimal bd = new BigDecimal(value);
        bd = bd.setScale(places, RoundingMode.HALF_UP);
        return bd.doubleValue();

Setting the radix (decimal separator)

Double.parseDouble always uses a dot as the decimal separator and does not use the default locale. To interpret localized string representations of a floating-point value, use subclasses of NumberFormat.

Example, setting the radix to a , comma:

DecimalFormat decimalFormat = (DecimalFormat) DecimalFormat.getInstance();
DecimalFormatSymbols decimalFormatSymbols = new DecimalFormatSymbols();
// Set decimal separator
String val = "10,2";
Double doubleValue = decimalFormat.parse(val).doubleValue();


To Integer

Double d = 5.25;
Integer i = d.intValue(); // i becomes 5
// or
double d = 5.25;
int i = (int) d;

To Long

Double myDouble = 3.41;

Test / Equality

See Floating point equality for the theory of the delta.

With Junit:

// Math.abs(expected - actual) < epsilon
private static final double DELTA = 1e-15;
Assert.assertEquals(double1, double2,DELTA);

Discover More
Java Conceptuel Diagram
Java - (Primitive|Native) Data Type

Java has a fixed set of primitive types: boolean, byte, short, int, long, char, float, and double. They can also be used in a wrapper class in order to enhance the functionalities....
Java Conceptuel Diagram
Java - Number

in Java. The abstract class Number is the superclass of platform classes representing numeric values that are convertible to the primitive types byte, double, float, int, long, and short. The...

Share this page:
Follow us:
Task Runner