Java basics: introduction to encapsulation, method overloading, and construction methods (constructors)

This article brings you the basics of Java: encapsulation - method overloading - introduction to construction methods (with code), so that you can have a preliminary understanding of them, and I hope it will be useful to you. help.

1. Encapsulation

• Encapsulation is Hide things you don’t want or shouldn’t tell others, and make things public that you can tell others.
• Method: Modify the access rights of attributes to restrict access to attributes. And create a pair of value methods and assignment methods for each attribute to access these attributes

class Dog{ String name;//成员变量 int age; private char genter;//加private变为私有属性，要提供方法才能在外部进行调用 public void setGenter(char genter){ //加if语句可以防止乱输入 if(genter=='男'||genter=='女'){ this.genter=genter;//this.name,这个name为成员变量 }else{ System.out.println("请输入正确的性别"); } } public char getGenter(){ return this.genter; } } public class Test1{ public static void main(String[] args){ Dog one=new Dog(); one.setGenter('女'); System.out.println(one.getGenter()); } }

2. Overloading of methods

Method overloading means that a class can define multiple methods with the same name but different parameters. When called, the corresponding method will be selected based on different parameter lists.

class Cal{ public void max(int a,int b){ System.out.println(a>b?a:b); } public void max(double a,double b){ System.out.println(a>b?a:b); } public void max(double a,double b,double c){ double max=a>b?a:b; System.out.println(max>c?max:c); } } public class Test1{ public static void main(String[] args){ Cal one=new Cal(); one.max(88.9,99.3,120); } }

3. Constructor (constructor)

• Use the new constructor method to create a new Object
• The constructor is a function defined in a java class to initialize the object
• The constructor has the same name as the class and has no return value

class Dog{ private String name; private int age; Dog(String name,int age){//构造方法，public可加可不加 this.name=name; this.age=age; System.out.println("名字："+this.name+"年龄："+this.age); } Dog(){ } void get(){//普通方法，public可写可不写 System.out.println("我是一个普通方法"); }14 15 }16 public class Test1{ public static void main(String[] args){ Dog one=new Dog("小明",26); Dog two=new Dog(); one.get(); two.get(); } }

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