10.30作业 AB城，构造方法私有化，this关键字

//第八次作业（包括匿名对象、单例模式饿汉式、自动生成对象args[]数组使用、静态关键字）

//1、

package practice;

class Person {
		private String name;
		private static int count;
		public Person(){
			count++;
			this.name="NONAME - " + count;
		}
		public Person(String name){
			this.name=name;
		}
		public String getInfo(){
			return "姓名:"+this.name;
		}
	}
	public class DemoOutput {
		public static void main(String args[]) {
			System.out.println(new Person().getInfo());
			System.out.println(new Person("A").getInfo());
			System.out.println(new Person("B").getInfo());
			System.out.println(new Person().getInfo());
		
	}
};

//2、

package practice;

class Person1{
	private String name;
	private static int count;
	public Person1(){
		count++;
		System.out.println("产生了"+count+"个实例化对象。");
	}
	public String getInfo(){
		return "姓名:"+this.name;
	}
};

public class DemoOutputA {
	public static void main(String args[]){
		new Person1();
		new Person1();
		new Person1();
		new Person1();
		new Person1();
	}
};

//3、

package practice;

class Person2{
	private String name;
	private int age;
	static String city="A城";
	public Person2(String name,int age){
		this.name=name;
		this.age=age;
	}
	public String getInfo(){
		return"姓名:"+this.name+",年龄:"+this.age+",城市:"+city;
	}
};

public class DemoOutputB {
	public static void main(String args[]){
		Person2 per1=new Person2("张三",30);
		Person2 per2=new Person2("李四",31);
		Person2 per3=new Person2("王五",30);
		System.out.println("==========信息修改之前==========");
		System.out.println(per1.getInfo());
		System.out.println(per2.getInfo());
		System.out.println(per3.getInfo());
		System.out.println("==========信息修改之前==========");
		Person2.city="B城";
		System.out.println(per1.getInfo());
		System.out.println(per2.getInfo());
		System.out.println(per3.getInfo());
	}

};

//4、

package practice;

class Single{
	private static Single instance=new Single();
	private Single(){//将构造方法私有化
	}
	public static Single getInstance(){
		return instance;
	}
	public void print(){
		System.out.println("hello world!!!");
	}
};

public class DemoOutputC {
	public static void main(String args[]){
		Single s=null;
		s=Single.getInstance();
		s.print();
	}

}

来源：https://www.cnblogs.com/zhuli-1/p/7763277.html

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构造方法