"Java" Java wrapper class, Java Automatic Packaging (boxing) and unpacking (unpacking)

Packing class

Everything in Java is an object, so many operations are for objects, and Java will automatically wrap the usual data types into objects of the corresponding classes.
Support for automatic package and unpacking after jdk1.5

Wrapper classes for common data types

Packing

Boxing is the object that changes the base data type to the corresponding class.

listnew ArrayList();//list的各种操作都是针对对象的list.add(5);//5本来是int类型的，现在自动包装成了Integer类的对象

Unpacking

Unpacking is to change the object of the corresponding class into the appropriate basic data type

list.get(0)//得到第0个位置的对象，然后将它拆箱为基本的数据类型 也就是5

"Java" Java wrapper class, Java Automatic Packaging (boxing) and unpacking (unpacking)