Classes, objects, packages

Source: Internet
Author: User

Structured programming and object-oriented;

The characteristics of an object are called attributes;

A class is an abstraction of an object that is the real column of a class;

The declaration of the package must be the first executable statement in the source file

Named with an inverted organization domain name.

The program is not executed around the task to be solved, but is resolved around the object in question to be solved, and each property of the object is represented as a member variable in the class.

Method One: Public String tosting () {//access modifier return value type, method name ([parameter list])

Return "" + variable name +;//method body--The function code block to be implemented

public String name;//Name

Public String sex;//Name

public int age;//Name

Public String suno;//Name


Method Two: public void introduce () {


public String name;//Name

Public String sex;//Name

public int age;//Name

Public String suno;//Name

System.out.println ("");


int i;//local variable, no value, can only be used in his declaration to

This: String return value type only with current object

To string method name protected represents the public protected

Private: Int Default

New keyword

This reference uses packages to organize classes

The package is used as a management to prevent duplication, which can be used in different packages and must be placed in the first sentence.

Com.lovo student = new COM lovo.student ();

Behavior of the object


1. Locate (set breakpoint) 2. Start Debugging 3. Step through observation changes 4. Modify.

Method signature

public string void Main (string []args)

Columns such as: The following method signature declares two form parameters, one is an int type and one is a float type

public float DIVTE (int x,float f)

In a static method, only static members can be directly called directly, and non-static members cannot be called directly

Second, in the member method, the static member can be called directly, non-static members. No static

Static Modified method: A statically member that is shared to all objects of a class

Static member: Class name. Call

Only values are passed in Java.

Method overloading

In a class, there are two and two methods with the same name, different parameter types and different parameter numbers.


A constructor is a special way in a class that is called to execute when a real column is created

The constructor method constructs a name that is consistent with the class.

Column: public class student{

Public student () {



Fist can only take numbers

By default, there is only one non-parametric construction method in the class

Public student () {


Stu.display ();

Import java.util.scanner;//Input

Scanner import= New Scanner (; output

Classes, objects, packages

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