JAVA学习第九课（关键字一）

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直接以代码解释：

class Man
{
	private int age;
	private String name;
	Man()
	{
		name= null;age = 0;
	}
	Man(String n)//正常直接打印"BLF,0",但是把n改为name呢，就会打印null，0
	{	name = n;  }//改成name虽然增加了阅读性，但是参数名进栈时，栈区已经有了一个局部变量名name，
                              那么name的赋值，只会把自己赋值给自己。如同int x = 5； x = x；
 	/*
	Man(String name)
	{
		this.name = name;//this关键字的作用就是说，这个对象的name，那么会进堆内存，就不会起冲突了
	} 
	*/
	Man(int a)
	{ age = a; }
	Man(int a,String n)
	{
		age = a;
		name = n;
	}
	void run()
	{
		System.out.println(name+","+age);//实际上这里省略了this.name+","+this.age
	}
}
public class Main 
{	
	public static void main (String[] args) 
	{
		Man jo = new Man("BLF");
		jo.run();
	}
}

class Man
{
	private int age;
	private String name;
	Man()
	{
		name= null;age = 0;
	}
	Man(String name)
	{	this.name = name;  }
	Man(int age)
	{ this.age = age; }
	Man(int age,String name)
	{
		this.age = age;
		this.name = name;
	}
	void run()
	{
		System.out.println(this.name+","+this.age);
	}
}
public class Main 
{	
	public static void main (String[] args) 
	{
		Man jo = new Man("BLF");
		jo.run();
	}
}

this 使用二：
this可以在构造函数里调用其他构造函数

错误演示：

class Man
{
	private int age;
	private String name;
	Man()
	{
		name= null;
		age = 0;
	}
	Man(String name)
	{	this.name = name; 
		
	}
	Man(int age)
	{
		this.age = age; 
		
	}
	Man(int age,String name)
	{
		//上面已经写过了，是不是就可以进行调用了呢？答案是否定的
		this.Man(name);//this代表了对象，对象要想进行是使用必须先初始化，但是
		this.Man(age);//这里还没有进行初始化，就开始使用，所以是错误的
		
	}
	void run()
	{
		System.out.println(this.name+","+this.age);
	}
}
public class Main 
{	
	public static void main (String[] args) 
	{
		Man jo = new Man(12,"BLF");//此处传2个参数
		jo.run();
	}
}

class Man
{
	private int age;
	private String name;
	Man()
	{
		name= null;
		age = 0;
	}
	Man(String name)
	{	
		this.name = name; 
	}
	Man(int age)
	{
		this.age = age; 
	}
	Man(int age,String name)
	{
		this(name);//调用上述构造函数，注意：必须放第一行，房子this.age  = age;下面就错，理由见下
		this.age = age;
	}
	void run()
	{
		System.out.println(this.name+","+this.age);
	}
}
public class Main 
{	
	public static void main (String[] args) 
	{
		Man jo = new Man(12,"BLF");
		jo.run();
	}
}

	Man(int age,String name)
	{
		this.name = name;//初始化BLF
		this.age = age;//初始化12
		
		this("gggg"); //改变BLF，变为gggg，故错误
	}

import java.security.cert.TrustAnchor;


class Man
{
	private int age;
	private String name;
	Man()
	{
		name= null;
		age = 0;
	}
	Man(String name)
	{	
		this.name = name; 
	}
	Man(int age)
	{
		this.age = age; 
	}
	Man(int age,String name)
	{
		this(name);//调用上述构造函数，注意：见下
		this.age = age;
	}
	public void run()
	{
		System.out.println(this.name+","+this.age);
	}
	/*判断两个人是否是同龄人*/
	public boolean judge(Man g)
	{
		return this.age == g.age;//这里的this代表jo2
			
	}
}
public class Main 
{	
	public static void main (String[] args) 
	{
		Man jo = new Man(12,"BLF");
		Man jo2 = new Man(12,"BLF2");
		boolean flag = jo2.judge(jo);
		if(flag==true)
			System.out.println("YES");
		else 
			System.out.println("NO");
	}
}

JAVA学习第九课（关键字一）

标签：style   blog   http   color   使用   java   ar   strong   2014   

原文地址：http://blog.csdn.net/wjw0130/article/details/39171769