Jerry Education 8

String s= "I Love you China";

Char[] Str=s.tochararray ();

Converts s into a character array.

Stringbuffer:string enhanced version.

StringBuffer statement:

StringBuffer sb=new StringBuffer ();//Create an empty StringBuffer object

StringBuffer sb=new StringBuffer ("AAA");//Create a variable storage AAA

Use of StringBuffer:

Sb.tostring ();//Convert to String type

Sb.append ("* *");//Append string

Use the length () and insert () of the StringBuffer class to implement the requirements.

Sb.reverse (); Implements the reversal (reversal) of the string.

Sb.delete (Start,end); Implements the deletion of strings (starting and ending positions).

Sb.replace (Start,end,replace); implements the substitution of the string, the start and end positions, and replace as the replacement content.

StringBuffer sb3=new stringbuffer ("ABCDEFG");

Sb3.replace (0, 3, "1111");

System. out. println (SB3);

The Replace method in string:

String s= "AAABBBCCCDDDEEEFFFGGG";

String S4=s.replace ("A", "1");

System. out. println (S4);

Steps:

① the Build object. StringBuffer sb=new StringBuffer ();

② assigns a value to an object (adds a string).

③ data processing.

④ used, set length=0. Sb.setlength (0);

Advantages of StringBuffer: Memory savings, more methods than string.

Basic type à packing class (packing)

ValueOf

Example: Byte bytevalue= byte. ValueOf ("21");

Packing class à basic type (unpacking)

Xxxvalue ()

Example: Integer integerid=new integer (25);

int intid= integerid.intvalue ();

int I=integer.parseint ("123"), the ability to convert a string into a basic data type.

The meaning of packaging class lies in object-oriented thinking.

"Classes and Objects"

Classes are summed up and abstracted from objects.

A class is a collection of a set of objects that have the same properties and methods.

The process of object-oriented design and abstraction

Describe a design with a class diagram

The process of design

① Discovery Class

② discovering the properties of a class

③ Methods for discovering classes

④ Optimization Design

The principle of abstraction

① the properties that the system is concerned about

The ② system focuses on methods

Use class diagrams to describe classes: for analysis and design classes, intuitive, easy to understand, tools for Office Visio.

The plus sign in the class diagram represents public, and the minus sign represents private.

Encapsulation Definition: Hides some information of a class inside a class, does not allow external programs to access directly, but through the method provided by the class to implement the operation and access to the hidden information.

Steps for encapsulation:

The property is privatized (private), then the get and set methods are set and then called in the test class.

Encapsulation Benefits: Hidden class Implementation details, easy to join control statements, easy to modify the implementation, only through the prescribed method to access data.

One of the three main characteristics of object-oriented: encapsulation.

The role of construction: allocating memory space to produce objects. Initialization The default construct.

Method overloading: Refers to multiple methods in the same class (method names are the same, parameter lists differ).

Constructor overloads.

Jerry Education 8