Wrapper classes for basic data type objects

First, the concept

The advantage of encapsulating a basic data type as an object is that more functional methods can be defined in the object to manipulate the data.

Second, common Operation 1. Common operation:

Used for conversions between the base data type and the string.

Basic data types	Packing class
Byte	Byte
Short	Short
Int	Integer
Long	Long
Float	Float
Double	Double
Char	Character
Boolean	Boolean

2.Object object parent of all objects

Object to basic data type conversions need to be directly converted through wrapper class string and base data type must also be done through wrapper class

Iii. Common Application Scenario 3.1 numeric values of the base type are converted to strings (string type)

There are two ways: a). Basic data type + "", B). String.valueof (basic data type)

int A  = ten= a + "" = string.valueof (a);

3.2String types of strings converted to basic data types

Wrapper classes that use basic data types

String STR3 = "n"; int i = integer.parseint (STR3); double d = double.parsedouble (STR3);

Conversions between 3.3 and binary

A) decimal conversion to other binary

// decimal conversion into binary System.out.println (integer.tobinarystring (30)); // 11110, // decimal into octal System.out.println (integer.tohexstring (30)); // 1e // convert decimal to hexadecimal System.out.println (integer.tooctalstring (30)); //  $

b) other conversions into decimal

System.out.println (Integer.parseint ("11110", 2)); //  -

3.4 Conversion of basic data types and wrapper classes

A). basic data type converted to wrapper class

New Integerin2= integer.valueof (30);

b). The wrapper class is converted into a basic data type

// jdk1.7 cannot be converted directly between int a = in.intvalue (); // jdk1.7 can then be converted by itself . int b  = in;

Wrapper classes for basic data type objects