Android實現計時與倒計時的幾種方法
阿新 • • 發佈:2018-12-18
方法一
Timer與TimerTask(Java實現)
public class timerTask extends Activity{ private int recLen = 11; private TextView txtView; Timer timer = new Timer(); public void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.timertask); txtView = (TextView)findViewById(R.id.txttime); timer.schedule(task, 1000 , 1000); // timeTask } TimerTask task = new TimerTask() { @Override public void run() { runOnUiThread(new Runnable() { // UI thread @Override public void run() { recLen--; txtView.setText(""+recLen); if(recLen < 0){ timer.cancel(); txtView.setVisibility(View.GONE); } } }); } };}
方法二TimerTask與Handler(不用Timer的改進型)
public class timerTask extends Activity{ private int recLen = 11; private TextView txtView; Timer timer = new Timer(); public void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.timertask); txtView = (TextView)findViewById(R.id.txttime); timer.schedule(task, 1000 , 1000); // timeTask } final Handler handler = new Handler(){ @Override public void handleMessage(Message msg){ switch (msg.what) { case 1: txtView.setText(""+recLen); if(recLen < 0){ timer.cancel(); txtView.setVisibility(View.GONE); } } } }; TimerTask task = new TimerTask() { @Override public void run() { recLen--; Message message = new Message(); message.what = 1; handler.sendMessage(message); } };}
方法三Handler與Message(不用TimerTask)
public class timerTask extends Activity{ private int recLen = 11; private TextView txtView; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.timertask); txtView = (TextView)findViewById(R.id.txttime); Message message = handler.obtainMessage(1); // Message handler.sendMessageDelayed(message, 1000); } final Handler handler = new Handler(){ public void handleMessage(Message msg){ // handle message switch (msg.what) { case 1: recLen--; txtView.setText("" + recLen); if(recLen > 0){ Message message = handler.obtainMessage(1); handler.sendMessageDelayed(message, 1000); // send message }else{ txtView.setVisibility(View.GONE); } } super.handleMessage(msg); } };}
方法四Handler與Thread(不佔用UI執行緒)
public class timerTask extends Activity{ private int recLen = 0; private TextView txtView; public void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.timertask); txtView = (TextView)findViewById(R.id.txttime); new Thread(new MyThread()).start(); // start thread } final Handler handler = new Handler(){ // handle public void handleMessage(Message msg){ switch (msg.what) { case 1: recLen++; txtView.setText("" + recLen); } super.handleMessage(msg); } }; public class MyThread implements Runnable{ // thread @Override public void run(){ while(true){ try{ Thread.sleep(1000); // sleep 1000ms Message message = new Message(); message.what = 1; handler.sendMessage(message); }catch (Exception e) { } } } }}
方法五Handler與Runnable(最簡單型)
public class timerTask extends Activity{ private int recLen = 0; private TextView txtView; public void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.timertask); txtView = (TextView)findViewById(R.id.txttime); handler.postDelayed(runnable, 1000); } Handler handler = new Handler(); Runnable runnable = new Runnable() { @Override public void run() { recLen++; txtView.setText("" + recLen); handler.postDelayed(this, 1000); } };}
計時與倒計時
方法1,方法2和方法3,都是倒計時
方法4,方法5,都是計時
計時和倒計時,都可使用上述方法實現(程式碼稍加改動)
UI執行緒比較
方法1,方法2和方法3,都是在UI執行緒實現的計時;
方法4和方法5,是另開Runnable執行緒實現計時
實現方式比較
方法1,採用的是Java實現,即Timer和TimerTask方式;
其它四種方法,都採用了Handler訊息處理
推薦使用
如果對UI執行緒互動要求不很高,可以選擇方法2和方法3
如果考慮到UI執行緒阻塞,嚴重影響到使用者體驗,推薦使用方法4,另起執行緒單獨用於計時和其它的邏輯處理
方法5,綜合了前幾種方法的優點,是最簡的
參考推薦: