从按下按钮开始，每秒运行一次方法

Question

I need a timer to start any time I press a button (on the button itself) that shows how many seconds it's been since it's pressed in real time. Whenever it's pressed again, timer is reset to 0 and starts incrementing again

I know this isn't the way to do it, the button works fine but the timer should be in onCreate? I'm not sure how this is supposed to work with a button

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        downloadedImg = (ImageView) findViewById(R.id.imageView);
    }

    public void clickAsync(View view) {

            new ImageDownloader().execute(downloadUrl);
            int seconds = 0;
            Button button = (Button) view;

            button.setText("Seconds since clicked: " + seconds);
            Timer timer = new Timer();

            //each time button is clicked, time is reset to 0 and increments in real time
            timer.scheduleAtFixedRate(new TimerTask()
            {
                public void run()
                {
                    seconds = 0;
                    seconds++;
                    button.setText("Seconds since clicked: " + seconds);
                }
            }, 0, 1000);
      }
}

Answer 1

try this: use a handler

 long startTime = 0;
 long elapsedTime ;

//runs without a timer by reposting this handler at the end of the runnable
Handler timerHandler = new Handler();
Runnable timerRunnable = new Runnable() {

    @Override
    public void run() {
        long millis = System.currentTimeMillis() - startTime;
        int seconds = (int) (millis / 1000);
        int minutes = seconds / 60;
        int hours = minutes / 60;
        seconds = seconds % 60;
        //textview for displaying time..
        timerTextView.setText(String.format("%d:%02d:%02d", hours, minutes, seconds));

        timerHandler.postDelayed(this, 1000);
    }
};

 b.setOnClickListener(new View.OnClickListener() { //b is your button

    @Override
    public void onClick(View v) {
        Button b = (Button) v;
        if (b.getText().equals("Stop")) {
            elapsedTime = System.currentTimeMillis() - startTime;
            timerHandler.removeCallbacks(timerRunnable);
            b.setText("Resume");
        } else {
            startTime = System.currentTimeMillis() - elapsedTime;
            timerHandler.postDelayed(timerRunnable, 0);
             Calendar cs = Calendar.getInstance();
            System.out.println("Current time => " + cs.getTime());
            SimpleDateFormat df = new SimpleDateFormat("HH:mm");
            String formattedDate = df.format(cs.getTime());
            timerTextView.setText(formattedDate);
            b.setText("Stop");
        }
    }
});

it will calculate the elapsed time and show time after stop...

Answer 2

Another easy way to do this is to use Handler

mHandler = new Handler();

Just call updateSec(); method on click of a button it'll update sec in interval of one seconds

Runnable UpdateRunnable = new Runnable() {

    @Override
    public void run() {
        updateSec();
    }
};

    public void updateSec() {
          mSeconds++;
          mHandler.postDelayed(UpdateRunnable, 1000);
     }

Example

button.setOnClickListener(new OnClickListener() {

public void onClick(View v) {
    mSeconds = 0;
    updateSec();//it'll update sec variable every second.
  }
});

Answer 3

You can use threads:

@Override
public void onClick(View view){
switch(view.getId()){
case R.id.button:
new Thread(new Runnable() {
@Override
public void run() {
try{
Thread.sleep(1000);
} catch(InterruptedException e) {
e.printStackTrace();
}
count++;
textView.post(new Runnable() {
@Override
public void run() {
textView.setText(count + "");
}
});
}
}
}).start;
break;
}
}

the view must be updated on main thread, and so you need to use post() method that has runnable instance as parameter.

Alternatively, you can also use AsyncTask.