Java Number class

Generally, when we need to use numbers, we usually use built-in data types, such as: byte, int, long, double, etc.

Example

int a = 5000;
float b = 13.65;
byte c = 0x4a;

However, in the actual development process, we often encounter situations where we need to use objects instead of built-in data types. In order to solve this problem, the Java language provides corresponding wrapper classes for each built-in data type.

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

This kind of packaging specially supported by the compiler is called boxing, so when the built-in data type is used as an object, the compiler will box the built-in type For packaging type. Similarly, the compiler can unbox an object into a built-in type. Number class belongs to java.lang package.

The following is an example of using an Integer object:

public class Test{

   public static void main(String args[]){
      Integer x = 5;
      x =  x + 10;
      System.out.println(x); 
   }
}

The compilation and running results of the above example are as follows:

15

When x is assigned an integer value, since x is an object, so the compiler has to box x. Then, in order for x to be added, x is unboxed.

Number method

The following table lists the methods implemented by Number subclasses: