3.6 Java Basics Summary ① wrapper class, basic data type, string conversion between

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

1Package com.string;2 /**3 * date:2016-3-3-pm 2:56:184 * Class_name:IntegerTest.java5 * Package_name:com.lovo.integer6 * Author:zhangyue7 * Description:8  */9  Public classIntegertest {Ten  One     /** A * @param args -      */ -      Public Static voidMain (string[] args) { the         //TODO auto-generated Method Stub -         //Basic Transfer Packaging - //int i0 = ten; - //integer in0 = new Integer (i0);//The first way: Call the wrapper class with the constructor of the basic type parameter to construct + //Integer in00 = i0;//the second way: After JDK1.5, the automatic sealing box - //Object obj = i0;//This is also the case, and then let the parent class refer to the Child class object + //System.out.println (in0); A          at         //Packaging to Basic - //integer in = new integer (+); - //int i = In.intvalue ();//The first way: Call the wrapper class object's ***value () - //int i0 = in;//second way: After JDK1.5, automatic unpacking - //System.out.println (i); -          in          -         //Wrap to String to //integer in = new Integer (123); + //String str = in.tostring ();//call ToString () of the wrapper class object - //System.out.println (str); the          *         //string to wrap $ //String str = "321";Panax Notoginseng //integer in = new Integer (str);//constructor for calling wrapper class with string argument - //System.out.println (in); the          +          A         //Basic Turn String the //int i = 9527; + //String str = integer.tostring (i);//The first way: Use the wrapper class with the parameter ToString () - //String str0 = i + "";//the second shameless way $ //System.out.println (str); $          -         //The most important--string turn to basic -String str ="54188"; the         inti = Integer.parseint (str);//call the wrapper class's parse*** () -System. out. println (i);Wuyi     } the  -}

integertest

3.6 Java Basics Summary ① wrapper class, basic data type, string conversion between