Android中的计时器倒计时

Question

我是Android应用程序开发的新手，对不起，如果我犯了任何错误。每当我按照我的代码访问homeActivity时，如何开始计时器倒计时。我感谢所有试图帮助我的人。谢谢。

public class homeActivity extends AppCompatActivity {
    private TextView userEmail; // Declaring email textview
    private TextView timerDisplay; // Declaring Timer Display textview

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_home);

        userEmail = (TextView) findViewById(R.id.userEmailID);
        timerDisplay = (TextView) findViewById(R.id.timer);
        // Retriving the the email id of the user which was passed from the sigin Activity
        userEmail.setText(getIntent().getExtras().getString("Email"));

        //use of a timer to display the notification 40 seconds as default for testing purposes
        new CountDownTimer(40000, 1000) {

            public void onTick(long millisUntilFinished) {
                // Displaying the following timer on the textview
                timerDisplay.setText("seconds remaining: " + millisUntilFinished / 1000);
            }
            //once the timer stops the following notification message is being Displayed
            public void onFinish() {
                final String title1="Break!";
                String subject1="It is time to take a break";
                String body1="20 minutes have passed";

                // Break taken is displayed on the textview
                timerDisplay.setText("Break Taken");
                // notification is diplayed
                NotificationManager notif=(NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);
                Notification notify=new Notification.Builder
                        (getApplicationContext()).setContentTitle(title1).setContentText(body1).
                        setContentTitle(subject1).setSmallIcon(R.mipmap.iclauncher).build();

                notify.flags |= Notification.FLAG_AUTO_CANCEL;
                notif.notify(0, notify);
            }
        }.start();
    }

    // Directed to rate us Activity
    public void rateusOperation (View v){
        Intent intent = new Intent(homeActivity.this,rateUsActivity.class);
        startActivity(intent);
    }

    // Directed to daily offers Activity
    public void dailyOffersOperation (View v){
        Intent intent = new Intent(homeActivity.this,dailyOffersActivity.class);
        startActivity(intent);
    }

    // directed to statistics Activity
    public void statisticsOperation (View v){
        Intent intent = new Intent(homeActivity.this,statisticsActivity.class);
        startActivity(intent);
    }

    // directed to privacy policy Activity
    public void privacyPolicyOperation (View v){
        Intent intent = new Intent(homeActivity.this,privacyPolicyActivity.class);
        startActivity(intent);
    }

    // Directed back to sign in Activity
    public void logoutOperation (View v){
        AlertDialog.Builder altDial = new AlertDialog.Builder (homeActivity.this);
        altDial.setMessage("Are You Sure ? ").setCancelable(true)
                .setPositiveButton("Yes", new DialogInterface.OnClickListener(){
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        Intent intent = new Intent(homeActivity.this,MainActivity.class);
                        startActivity(intent);
                        finish();
                    }
                })
                .setNegativeButton("No", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.cancel();
                    }
                });
        AlertDialog alert = altDial.create();
        alert.setTitle("You want to Logout ");
        alert.show();
    }
}

Answer 1

public class homeActivity extends AppCompatActivity 
{
    private TextView userEmail; // Declaring email textview
    private TextView timerDisplay; // Declaring Timer Display textview

    @Override
    protected void onCreate(Bundle savedInstanceState)
     {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_home);

        userEmail = (TextView) findViewById(R.id.userEmailID);
        timerDisplay = (TextView) findViewById(R.id.timer);
        // Retriving the the email id of the user which was passed from the sigin Activity
        userEmail.setText(getIntent().getExtras().getString("Email"));

        final CounterClass timer2 = new CounterClass(4000, 1000);
                timer2.start();
    }

    // Directed to rate us Activity
    public void rateusOperation (View v){
        Intent intent = new Intent(homeActivity.this,rateUsActivity.class);
        startActivity(intent);
    }

    // Directed to daily offers Activity
    public void dailyOffersOperation (View v){
        Intent intent = new Intent(homeActivity.this,dailyOffersActivity.class);
        startActivity(intent);
    }

    // directed to statistics Activity
    public void statisticsOperation (View v){
        Intent intent = new Intent(homeActivity.this,statisticsActivity.class);
        startActivity(intent);
    }

    // directed to privacy policy Activity
    public void privacyPolicyOperation (View v){
        Intent intent = new Intent(homeActivity.this,privacyPolicyActivity.class);
        startActivity(intent);
    }

    // Directed back to sign in Activity
    public void logoutOperation (View v){
        AlertDialog.Builder altDial = new AlertDialog.Builder (homeActivity.this);
        altDial.setMessage("Are You Sure ? ").setCancelable(true)
                .setPositiveButton("Yes", new DialogInterface.OnClickListener(){
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        Intent intent = new Intent(homeActivity.this,MainActivity.class);
                        startActivity(intent);
                        finish();
                    }
                })
                .setNegativeButton("No", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.cancel();
                    }
                });
        AlertDialog alert = altDial.create();
        alert.setTitle("You want to Logout ");
        alert.show();
    }
public class CounterClass extends CountDownTimer
    {
        TextView conter;
        public CounterClass(long millisInFuture, long countDownInterval)
        {
            super(millisInFuture, countDownInterval);

        }
        @Override
        public void onFinish()
        {
             final String title1="Break!";
                String subject1="It is time to take a break";
                String body1="20 minutes have passed";

                // Break taken is displayed on the textview
                timerDisplay.setText("Break Taken");
                // notification is diplayed
                NotificationManager notif=(NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);
                Notification notify=new Notification.Builder
                        (getApplicationContext()).setContentTitle(title1).setContentText(body1).
                        setContentTitle(subject1).setSmallIcon(R.mipmap.iclauncher).build();

                notify.flags |= Notification.FLAG_AUTO_CANCEL;
                notif.notify(0, notify);
        }
        @SuppressLint("NewApi")
        @TargetApi(Build.VERSION_CODES.GINGERBREAD)
        @Override
        public void onTick(long millisUntilFinished)
        {
            long millis = millisUntilFinished;
            String hms = String.format("%02d:%02d",
                    TimeUnit.MILLISECONDS.toMinutes(millis) - TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(millis)),
                    TimeUnit.MILLISECONDS.toSeconds(millis) - TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(millis)));

            timerDisplay.setText(hms);
        }
    }

}