TimerTask 更新UI線程

今天在犯了一個愚蠢的錯誤，TimerTask中更新UI界面了，難怪半天沒反應。

 

在網上搜了一篇Timer更新UI的帖子轉過來。

 

錯誤寫法：

package com.test;
import java.util.Timer;
import java.util.TimerTask;
import android.app.Activity;
import android.os.Bundle;
public class TestTimer_Wrong extends Activity {
    Timer timer = new Timer();
    TimerTask task = new TimerTask(){
        public void run() {
                       setTitle("hear me?");
        }
    };
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        timer.schedule(task, 10000);
    }
}

 

TimerTask 裏面直接作UI更新，沒有在UIThread裏面。與Java的EDT線程，是同一律念。

正確寫法一　：　交由UI Thread處理

 

import java.util.Timer;
import java.util.TimerTask;
import android.app.Activity;
import android.os.Bundle;
public class TestTimer extends Activity {
    Timer timer = new Timer();
    TimerTask task = new TimerTask(){
        public void run() {

            runOnUiThread(new Runnable(){
            @Override
            public void run() {
                setTitle("hear me?");
            }});
            }
    };
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        timer.schedule(task, 10000);
    }
}

 

正確寫法二　：由Handler處理UI　更新。

package com.test;

import java.util.Timer;
import java.util.TimerTask;

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

public class TestTimer extends Activity {

    Timer timer = new Timer();
    Handler handler = new Handler(){

        public void handleMessage(Message msg) {
            switch (msg.what) {
            case 1:
                setTitle("hear me?");
                break;
            }
            super.handleMessage(msg);
        }

    };
    TimerTask task = new TimerTask(){

        public void run() {
            Message message = new Message();
            message.what = 1;
            handler.sendMessage(message);
        }

    };
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        timer.schedule(task, 10000);
    }
}