Java - Numbers Class

Normally, when we work with Numbers, we use primitive data types such as byte, int, long, double, etc.

Consider the below example:

int i = 5000;
float gpa = 13.65f;
double mask = 125;

Sometimes, there may be some situations where we need to use objects instead of primitive data types. To achieve this, Java provides wrapper classes.

All the wrapper classes (Integer, Long, Byte, Double, Float, Short) are subclasses of the abstract class Number.

Java Number Class

The Number class is an abstract class in java.lang package. It is the superclass of the classes that represent numeric values convertible to primitive data types such as byte, short, int, long, float, and double.

The object of the wrapper class contains or wraps its respective primitive data type. Converting primitive data types into object is called boxing, and this is taken care by the compiler. Therefore, while using a wrapper class you just need to pass the value of the primitive data type to the constructor of the Wrapper class.

And the Wrapper object will be converted back to a primitive data type, and this process is called unboxing. The Number class is part of the java.lang package.

Following is an example of boxing and unboxing −

Example

In this example, we've showcase use of primitives and their operations using a wrapper class. In first statement we've assigned an int to an Integer object x which is termed as boxing. In second statment, we're adding 10 to x which requires x to be unboxed as int and addition is performed and result is assigned back to the variable x and printed.

public class Test {

   public static void main(String args[]) {
      Integer x = 5; // boxes int to an Integer object
      x =  x + 10;   // unboxes the Integer to a int
      System.out.println(x); 
   }
}

This will produce the following result −

Output

15

When x is assigned an integer value, the compiler boxes the integer because x is integer object. Later, x is unboxed so that they can be added as an integer.

Java Number Class Methods

Following is the list of the instance methods that all the subclasses of the Number class implements −

Java Number: Wrapper Classes

Following is the list of the wrapper classes that all the subclasses of the Number class −