stop watch logic

Question

I want to develop a simple stop watch logic in android.

On clicking a list view the timer should start and on clicking the button the timer should stop. Can anyone please guide me. Any sample code will be of great help

Answer 1

Use the Stopwatch Class (For higher precision use System.nanoTime())

Add a Start() event and Stop() event on Button Presses. You'll need to update the UI so use a Thread/Handler Combination.

This should get you started.

EDIT: Added Code. (Nice Exercise! :) )

Use the Refresh_Rate to configure how often your UI is updated.

import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.TextView;  public class Main extends Activity implements OnClickListener{      final int MSG_START_TIMER = 0;     final int MSG_STOP_TIMER = 1;     final int MSG_UPDATE_TIMER = 2;      Stopwatch timer = new Stopwatch();     final int REFRESH_RATE = 100;      Handler mHandler = new Handler()     {         @Override         public void handleMessage(Message msg) {             super.handleMessage(msg);             switch (msg.what) {             case MSG_START_TIMER:                 timer.start(); //start timer                 mHandler.sendEmptyMessage(MSG_UPDATE_TIMER);                 break;              case MSG_UPDATE_TIMER:                 tvTextView.setText(""+ timer.getElapsedTime());                 mHandler.sendEmptyMessageDelayed(MSG_UPDATE_TIMER,REFRESH_RATE); //text view is updated every second,                  break;                                  //though the timer is still running             case MSG_STOP_TIMER:                 mHandler.removeMessages(MSG_UPDATE_TIMER); // no more updates.                 timer.stop();//stop timer                 tvTextView.setText(""+ timer.getElapsedTime());                 break;              default:                 break;             }         }     };      TextView tvTextView;     Button btnStart,btnStop;      /** Called when the activity is first created. */     @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.main);         tvTextView = (TextView)findViewById(R.id.TextView01);          btnStart = (Button)findViewById(R.id.Button01);         btnStop= (Button)findViewById(R.id.Button02);         btnStart.setOnClickListener(this);         btnStop.setOnClickListener(this);      }      public void onClick(View v) {         if(btnStart == v)         {             mHandler.sendEmptyMessage(MSG_START_TIMER);         }else         if(btnStop == v){             mHandler.sendEmptyMessage(MSG_STOP_TIMER);         }     } }