Android定时器Timer的停止和重启实现代码

本文介绍了Android定时器Timer的停止和重启实现代码，分享给大家，具体如下：

7月份做了一个项目，利用自定义控件呈现一幅动画，当时使用定时器来控制时间，但是当停止开启时总是出现问题。一直在寻找合理的方法解决这个问题，一直没有找到，最近终于找到了合理的方法来解决这个问题。

大家如何查询有关资料，一定知道timer,timertask取消的方式是采用Timer.cancel()和mTimerTask.cancel()，可是大家发现这种发式取消后，再次开始timer时，会报错

 FATAL EXCEPTION: main
         Process: com.example.zhongzhi.gate_control_scheme, PID: 2472
         java.lang.IllegalStateException: Timer already cancelled.
           at java.util.Timer.sched(Timer.java:397)
           at java.util.Timer.schedule(Timer.java:248)
           at com.example.zhongzhi.gate_control_scheme.MainActivity.onClick(MainActivity.java:401)
           at android.view.View.performClick(View.java:5637)
           at android.view.View$PerformClick.run(View.java:22429)
           at android.os.Handler.handleCallback(Handler.java:751)
           at android.os.Handler.dispatchMessage(Handler.java:95)
           at android.os.Looper.loop(Looper.java:154)
           at android.app.ActivityThread.main(ActivityThread.java:6119)
           at java.lang.reflect.Method.invoke(Native Method)
           at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
           at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

这个问题的解决采用cancle(),取消timer后，还需要清空timer。合理的代码应该是这样的：

mTimer.cancel();
mTimer = null;
mTimerTask.cancel();
mTimerTask = null;

关键的问题解决完了，下面给出我的案例代码Mainactivity.Java：

public class MainActivity extends AppCompatActivity {
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.activity_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);
}
}
}

xml部分代码：

<?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

string部分代码：

<?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

上面就是我的源代码，如果大家有什么问题可以留言进行探讨。

以上就是本文的全部内容，希望对大家的学习有所帮助。