3.6 complement

Wrapper class, basic data type, string conversion between each other

Each base data type has a corresponding wrapper type

wrapper classes, basic data types, and string conversions between the three are important when converting between them;

One, String to other

string→ Package Type
1, Integer (String str)
Call the wrapper class with a string parameter construct

string→ Basic data types
☆string→int calling the parseint method of the wrapper class

Second, packaging class to other

→string
Call the ToString method of the wrapper class object

→ Basic types
① calling the Xxxvalue method of the wrapper class
Methods of wrapping classes, related to objects, non-static, without reference

After ②jdk1.5, direct assignment
int i = Integer
Since unpacking

III. basic data types transfer to other

→string
①5 + ""
②str = integer.tostring (i);
Using the parameter tostring method of the wrapper class

→ Packaging
① calling the construct of the wrapper class new
After ②jdk1.5, direct assignment =
Automatic Seal box

Object obj = 10;
This is also an automatic enclosure, which refers to the parent class's reference to the Child class object

integertest

3.6 complement