Android定時(shí)器Timer的停止和重啟實(shí)現(xiàn)代碼

2019-12-12 02:21:37

字體：大中小

供稿：網(wǎng)友

本文介紹了Android定時(shí)器Timer的停止和重啟實(shí)現(xiàn)代碼，分享給大家，具體如下：

7月份做了一個(gè)項(xiàng)目，利用自定義控件呈現(xiàn)一幅動(dòng)畫，當(dāng)時(shí)使用定時(shí)器來控制時(shí)間，但是當(dāng)停止開啟時(shí)總是出現(xiàn)問題。一直在尋找合理的方法解決這個(gè)問題，一直沒有找到，最近終于找到了合理的方法來解決這個(gè)問題。

大家如何查詢有關(guān)資料，一定知道timer,timertask取消的方式是采用Timer.cancel()和mTimerTask.cancel()，可是大家發(fā)現(xiàn)這種發(fā)式取消后，再次開始timer時(shí)，會(huì)報(bào)錯(cuò)

 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)

這個(gè)問題的解決采用cancle(),取消timer后，還需要清空timer。合理的代碼應(yīng)該是這樣的：

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

關(guān)鍵的問題解決完了，下面給出我的案例代碼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部分代碼：

<?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部分代碼：

<?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>

上面就是我的源代碼，如果大家有什么問題可以留言進(jìn)行探討。

以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持武林網(wǎng)。

上一篇：Android iconify 使用詳解

下一篇：Android實(shí)現(xiàn)RecyclerView添加分割線的簡(jiǎn)便方法