Android中定时器Timer和TimerTask的启动，停止，暂停，继续等操作实例

Dear 丶 2022-06-16 20:07 702阅读 0赞

下面是一个在Android中使用定时器Timer和TimerTask的启动，停止，暂停，继续等操作的demo。

需要注意的问题主要有两点：

1、Timer和TimerTask在调用cancel()取消后不能再执行 schedule语句，否则提示出错，提示如下：

D/AndroidRuntime( 6672): Shutting down VM
    W/dalvikvm( 6672): threadid=1: thread exiting with uncaught exception (group=0x40018560)
    E/AndroidRuntime( 6672): FATAL EXCEPTION: main
    E/AndroidRuntime( 6672): java.lang.IllegalStateException: Timer was canceled
    E/AndroidRuntime( 6672): 	at java.util.Timer.scheduleImpl(Timer.java:563)
    E/AndroidRuntime( 6672): 	at java.util.Timer.schedule(Timer.java:483)
    E/AndroidRuntime( 6672): 	at com.snowdream.timerdemo.TimerDemoActivity$2.onClick(TimerDemoActivity.java:73)
    E/AndroidRuntime( 6672): 	at android.view.View.performClick(View.java:2501)
    E/AndroidRuntime( 6672): 	at android.view.View$PerformClick.run(View.java:9107)
    E/AndroidRuntime( 6672): 	at android.os.Handler.handleCallback(Handler.java:587)
    E/AndroidRuntime( 6672): 	at android.os.Handler.dispatchMessage(Handler.java:92)
    E/AndroidRuntime( 6672): 	at android.os.Looper.loop(Looper.java:130)
    E/AndroidRuntime( 6672): 	at android.app.ActivityThread.main(ActivityThread.java:3835)
    E/AndroidRuntime( 6672): 	at java.lang.reflect.Method.invokeNative(Native Method)
    E/AndroidRuntime( 6672): 	at java.lang.reflect.Method.invoke(Method.java:507)
    E/AndroidRuntime( 6672): 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
    E/AndroidRuntime( 6672): 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
    E/AndroidRuntime( 6672): 	at dalvik.system.NativeStart.main(Native Method)
    W/ActivityManager(  154):   Force finishing activity com.snowdream.timerdemo/.TimerDemoActivity
    W/ActivityManager(  154): Activity pause timeout for HistoryRecord{40550560 com.snowdream.timerdemo/.TimerDemoActivity}
    W/ActivityManager(  154): Activity destroy timeout for HistoryRecord{40550560 com.snowdream.timerdemo/.TimerDemoActivity}
    D/dalvikvm(  800): GC_EXPLICIT freed 13K, 58% free 3127K/7431K, external 0K/0K, paused 70ms
    D/dalvikvm(  562): GC_EXPLICIT freed 59K, 51% free 2935K/5959K, external 245K/512K, paused 84ms
    I/ActivityManager(  154): Start proc com.android.email for service com.android.email/.service.MailService: pid=6691 uid=10019 gids={3003, 1015}

2、只能在UI主线程中更新控件/组件。在其他线程中，更新控件/组件，会提示出错，提示如下：

**（注：这种情况下，可以通过Hander发送消息的方式来更新控件/组件，详情参考例子。）**

E/AndroidRuntime( 6309): android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
    E/AndroidRuntime( 6309): 	at android.view.ViewRoot.checkThread(ViewRoot.java:2941)
    E/AndroidRuntime( 6309): 	at android.view.ViewRoot.invalidateChild(ViewRoot.java:643)
    E/AndroidRuntime( 6309): 	at android.view.ViewRoot.invalidateChildInParent(ViewRoot.java:669)
    E/AndroidRuntime( 6309): 	at android.view.ViewGroup.invalidateChild(ViewGroup.java:2511)
    E/AndroidRuntime( 6309): 	at android.view.View.invalidate(View.java:5296)
    E/AndroidRuntime( 6309): 	at android.widget.TextView.checkForRelayout(TextView.java:5533)
    E/AndroidRuntime( 6309): 	at android.widget.TextView.setText(TextView.java:2730)
    E/AndroidRuntime( 6309): 	at android.widget.TextView.setText(TextView.java:2598)
    E/AndroidRuntime( 6309): 	at android.widget.TextView.setText(TextView.java:2573)
    E/AndroidRuntime( 6309): 	at com.snowdream.timerdemo.TimerDemoActivity$1.run(TimerDemoActivity.java:48)
    E/AndroidRuntime( 6309): 	at java.util.Timer$TimerImpl.run(Timer.java:284)

Demo源码如下：

TimerDemoActivity.java

package com.snowdream.timerdemo;
    
    import java.util.Timer;
    import java.util.TimerTask;
    
    import android.app.Activity;
    import android.os.Bundle;
    import android.os.Handler;
    import android.os.Message;
    import android.util.Log;
    import android.view.View;
    import android.widget.Button;
    import android.widget.TextView;
    
    public class TimerDemoActivity extends Activity {
    
    	private static String  TAG = "TimerDemo";
    
    	private TextView mTextView = null;
    	private Button mButton_start = null;
    	private Button mButton_pause = null;
    
    	private Timer mTimer = null;
    	private TimerTask mTimerTask = null;
    
    	private Handler mHandler = null;
    	
    	private static int count = 0;
    	private boolean isPause = false;
    	private boolean isStop = true;
    
    	private static int delay = 1000;  //1s
    	private static int period = 1000;  //1s
    
    	private static final int UPDATE_TEXTVIEW = 0;
    	
    	@Override
    	public void onCreate(Bundle savedInstanceState) {
    		super.onCreate(savedInstanceState);
    		setContentView(R.layout.main);
    
    		mTextView = (TextView)findViewById(R.id.mytextview); 
    		mButton_start = (Button)findViewById(R.id.mybutton_start);
    		mButton_pause = (Button)findViewById(R.id.mybutton_pause);
    
    
    		mButton_start.setOnClickListener(new Button.OnClickListener() {
    			public void onClick(View v) {
    				if (isStop) {
    					Log.i(TAG, "Start");
    				} else {
    					Log.i(TAG, "Stop");
    				}
    
    				isStop = !isStop;
    
    				if (!isStop) {
    					startTimer();
    				}else {
    					stopTimer();
    				}
    
    				if (isStop) {
    					mButton_start.setText(R.string.start);
    				} else {
    					mButton_start.setText(R.string.stop);
    				}
    			}
    		});
    
    		mButton_pause.setOnClickListener(new Button.OnClickListener() {
    			public void onClick(View v) {
    				if (isPause) {
    					Log.i(TAG, "Resume");
    				} else {
    					Log.i(TAG, "Pause");
    				}
    
    				isPause = !isPause;
    
    				if (isPause) {
    					mButton_pause.setText(R.string.resume);
    				} else {
    					mButton_pause.setText(R.string.pause);
    				}
    			}
    		});
    		
    		mHandler = new Handler(){
    
    			@Override
    			public void handleMessage(Message msg) {
    				switch (msg.what) {
    				case UPDATE_TEXTVIEW:
    					updateTextView();
    					break;
    				default:
    					break;
    				}
    			}
    		};
    	}
    
    	private void updateTextView(){
    		mTextView.setText(String.valueOf(count));
    	}
    
    	private void startTimer(){
    		if (mTimer == null) {
    			mTimer = new Timer();
    		}
    
    		if (mTimerTask == null) {
    			mTimerTask = new TimerTask() {
    				@Override
    				public void run() {
    					Log.i(TAG, "count: "+String.valueOf(count));
    					sendMessage(UPDATE_TEXTVIEW);
    					
    					do {
    						try {
    							Log.i(TAG, "sleep(1000)...");
    							Thread.sleep(1000);
    						} catch (InterruptedException e) {
    						}	
    					} while (isPause);
    					
    					count ++;  
    				}
    			};
    		}
    
    		if(mTimer != null && mTimerTask != null )
    			mTimer.schedule(mTimerTask, delay, period);
    
    	}
    
    	private void stopTimer(){
    		
    		if (mTimer != null) {
    			mTimer.cancel();
    			mTimer = null;
    		}
    
    		if (mTimerTask != null) {
    			mTimerTask.cancel();
    			mTimerTask = null;
    		}	
    
    		count = 0;
    
    	}
    	
    	public void sendMessage(int id){
    		if (mHandler != null) {
    			Message message = Message.obtain(mHandler, id);   
    			mHandler.sendMessage(message); 
    		}
    	}
    }

layout-main.xml

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical" >
    
        <TextView
            android:id="@+id/mytextview"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:text="@string/number" />
    
        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:orientation="horizontal" >
    
            <Button
                android:id="@+id/mybutton_start"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/start" />
    
            <Button
                android:id="@+id/mybutton_pause"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/pause" />
        </LinearLayout>
    
    </LinearLayout>

strings.xml

<?xml version="1.0" encoding="utf-8"?>
    <resources>
    
        <string name="app_name">TimerDemo</string>
        <string name="number">0</string>
        <string name="start">start</string>
        <string name="stop">stop</string>
        <string name="pause">pause</string>
        <string name="resume">resume</string>
    
    </resources>

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[http://download.csdn.net/detail/yang\_hui1986527/3922447][http_download.csdn.net_detail_yang_hui1986527_3922447]

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