Three data transfer methods between java multithreading

package com.test.sjcd;

public class Data {
    
    
	
	private int value;

	public int getValue() {
    
    
		return value;
	}

	public void setValue(int value) {
    
    
		this.value = value;
	}
	
	

}

package com.test.sjcd;

public class SubThread extends Thread{
    
    
	
	  private Data data;
	  
	  public Data getData() {
    
    
		return data;
	}

	public void setData(Data data) {
    
    
		this.data = data;
	}

	public SubThread()
	  {
    
    
		  
	  }
	  
	  public SubThread(Data data)
	  {
    
    
		  this.data=data;		  
		  
	  }

	  public void run()
	  {
    
    
		 System.out.println("子线程内:"+data.getValue());
		 
		 this.data.setValue(200); //将值做修改
		 
		 Test.callback(); //调用回调函数
	  }
}

package com.test.sjcd;

public class Test {
    
    

	static boolean flag=false;
	/**
	 * @param args
	 */
	public static void main(String[] args) {
    
    
		// TODO Auto-generated method stub

		Data data=new Data();
		
		data.setValue(20);
		
		System.out.println("调用子线程前，值为"+data.getValue());
		
		//第一种传值方式 通过构造函数传值
		//SubThread subThread=new SubThread(data);
		SubThread subThread=new SubThread();
		//第二种传值方式 通过属性赋值
		subThread.setData(data);
		
		subThread.start();
		
		//第三种方式 使用回调函数
		while(!flag);
		
		System.out.println("调用子线程后,值为"+data.getValue());
		
		
		
	}
	
	public static void callback()
	{
    
    
		 flag=true;		
	}

}