1、問題

我們要在一個類裡面變數或者函式變化需要改變另外一個類裡面的東西，這個時候java裡面除了介面回撥之外，我們還可以用註冊Handler來實現

2、程式碼實現

1、MainActivity.java檔案

package com.example.handlercallback;

import android.app.Activity;
import android.os.Bundle;

public class MainActivity extends Activity {
	
	public Control mControl;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		mControl = new Control();
		new Thread(new Runnable(){
			@Override
			public void run() {
				Manager.getInstance().sendSuccessMessage();
				try {
					Thread.sleep(2000);
					Manager.getInstance().sendFailMessage();
				} catch (InterruptedException e) {
				}
			}
		}).start();
	}

}
 

2、Control.java檔案

package com.example.handlercallback;


import android.os.Handler;
import android.os.Message;
import android.util.Log;

public class Control {
	
	public static final String TAG  = "Control";
	public static final int OK = 0;
	public static final int fail = -1;

	private Handler svpnSericeHandler = new Handler() {
		public void handleMessage(Message msg) {
			switch (msg.what) {
			case Control.OK:
				Log.d(TAG, "msg.what = " + msg.what);
				return;
			case Control.fail:
				Log.d(TAG, "msg.what = " + msg.what);
				return;
			default:
				Log.d(TAG, "msg.what = " + msg.what);
				break;
			}
		}
	};
	
	public Control() {
		Manager.getInstance().setHandler(svpnSericeHandler);
	}
	
}
 

3、Manager.java檔案

package com.example.handlercallback;

import android.os.Handler;

public class Manager {
	
	public static final String TAG = "Manager";
	
	private static Manager mInstance;
	
	public Handler mHandler;
	
	public synchronized static Manager getInstance() {
		if (mInstance == null) {
			mInstance = new Manager();
		}
		return mInstance;
	}
	
	public void setHandler(Handler handler) {
		this.mHandler = handler;
	}
	
	public void sendSuccessMessage() {
		mHandler.sendEmptyMessage(Control.OK);
	}
	
	public void sendFailMessage() {
		mHandler.sendEmptyMessage(Control.fail);
	}
}
 

3、結果展示

                Control  D  msg.what = 0
               Timeline  I  Timeline: Activity_idle id: [email protected] time:79529768
                Control  D  msg.what = -1