Java Starter Series -11- Classes and objects

This article will help you understand the use of classes and objects

Object: An entity used to describe objective things, consisting of a set of properties and methods.

Attributes: Are the characteristics of the object, such as height, weight, color

Methods: The behavior of an object, such as running and jumping

Classes: Classes are templates that define the properties and methods that an object will have. Classes are abstract concepts such as “books”

Define the class

Grammar:

public classThe name of the class{properties1Type attribute of1; The type attribute n of attribute n; ... methods1; Methods m; ... }Copy the code

To define a class, you can follow three steps: 1. Define the name of the class; 2. Write the methods of the class

Tap: Student class

public class Student{
    String name;// Name attribute
    int age;/ / age
    public void sayHi(a){
        System.out.println("Hello, I am:"+name+",我 "+age+"The"); }}Copy the code

Using the object

Grammar:

Class name Object name =newThe name of the class ();Copy the code

Click: Create student object

public class Student{
    String name;// Name attribute
    int age;/ / age
    public void sayHi(a){
        System.out.println("Hello, I am:"+name+",我 "+age+"The");
    }
    public static void main(String[] args) {
		Student student=new Student();
		student.name="White";
		student.age=20; student.sayHi(); }}Copy the code

Reference class property: object name. Property refers to the method of the class: the object name. The method name ()

OOP

Object Oriented Programming (OOP) is a kind of Programming architecture rather than face to face Programming with objects.

Why object oriented:

Object orientation is consistent with human thinking habits and can better use computers to simulate the real world.

Object orientation improves the reusability of programs, programs can be built like building blocks, reduce code, improve the speed of development.

Information hiding improves program maintainability and security, reducing the risk of large-scale software development

Java is object-oriented language, object-oriented development is the trend of development.

Documentation comments

Earlier we learned that there are two types of comments, single-line comments // and /** / multi-line comments. There is also a comment for generating help documents, document comments /** */. Type /** enter in Eclipse and the rest will be generated automatically.

Presentation:

import java.util.Arrays;
/** * Test class *@author Jackie
 *
 */
public class Test {
    /** * quantity */
    int num;
    /** * program entry *@param args
     */
    public static void main(String[] args) {
        String[] names= {"Zhang"."Bill"}; System.out.println(Arrays.toString(names)); }}Copy the code

Some common Javadoc tags are listed below

The finished code contains comments, and you can use the command to generate the help document javadoc -d apidoc *.java

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