JAVA笔记2__类/封闭性/构造方法/方法的重载/匿名对象

public class Main {
    public static void main(String[] args) {
        Chicken c1 = new Chicken();
        Chicken c2 = null;
        c1.eat();
        System.out.println(c1.age);
        c2 = c1;
        c2.eat();
    }
}

class Chicken{
    int color;
    char sex;
    int age;
    void eat(){
        System.out.println("chikcen1 eat rice.");
    }
}

public class Main {
    public static void main(String[] args) {
        Person p1 = new Person();
        p1.setName("dining");
        System.out.println(p1.getName());
    }
}

/**
 * 封闭性
 * 1.把属性设成私有
 * 2.为属性提供get/set方法
 */
class Person{
    private String name;
    private int age;
    public void setName(String name){
        this.name = name;
    }
    public String getName(){
        return name;
    }
}

public class Main {
    public static void main(String[] args) {
        Duck p1 = new Duck("fishDining");
        System.out.println(p1.getName());
        Duck p2 = new Duck("fishDining2",20);
        System.out.println(p2.getName()+" "+p2.getAge());
    }
}

/**
 * 构造方法
 * 1.默认（无参）构造方法：public Duck(){}
 * 2.带一个(多个)参数的构造方法：Public Duck(String name){this.name=name;}
 */
class Duck{
    private String name;
    private int age;
    
    //默认构造方法
    public Duck(){}
    public Duck(String name,int age){
        this.name = name;
        this.age = age;
    }
    public Duck(String name){
        this.name = name;
        System.out.println("I'm a duck.");
    }
    public void setName(String name){
        this.name = name;
    }
    public String getName(){
        return name;
    }
    public void setAge(int age){
        this.age = age;
    }
    public int getAge(){
        return age;
    }
}

public class Main {
    public static void main(String[] args) {
        Woman w1 = new Woman();
        w1.aa();
        w1.aa("keke1");
        w1.aa("keke1",21);
    }
}

/**
 * 方法的重载(方法具有相同名字，但具有不同的参数和不同的定义)
 */
class Woman{
    public String name;
    public int age;
    
    public void aa(){
        System.out.println("aa1");
    }
    public void aa(String name){
        System.out.println("aa2:"+name);
    }
    public void aa(String name,int age){
        System.out.println("aa2:"+name+":"+age);
    }
}

import java.util.Random;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        new Woman().aa(); //生成一个匿名对象
        new Woman().aa("loveu1");
    }
}

/**
 * 匿名对象：定义一个没有名称的对象，特点：只能使用一次（直接在堆中开辟内存空间，使用后成为垃圾对象，被GC回收）
 */
class Woman{
    public String name;
    public int age;
    
    public void aa(){
        System.out.println("aa1");
    }
    public void aa(String name){
        System.out.println("aa2:"+name);
    }
    public void aa(String name,int age){
        System.out.println("aa2:"+name+":"+age);
    }
}