how to set a timer and perform an action for it, in android application

Question

I'm developing an application in Android Studio. How i can set timer and then perform an action at that time?

Im getting system date and time... and getting date and time by user.. then i have to compare both and perform an action for it. Need Help Here is my code:

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import android.app.DatePickerDialog;
import android.app.TimePickerDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.TextClock;
import android.widget.TextView;
import android.widget.TimePicker;

import java.sql.Time;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.time.Year;
import java.util.Calendar;

public class MainActivity extends AppCompatActivity implements
        DatePickerDialog.OnDateSetListener, TimePickerDialog.OnTimeSetListener{

    TextView textView, textView2;
    TextClock textClock;
    TimePicker timePicker;
    DatePicker datePicker;
    Button button, button2;
    Calendar calendar;
    SimpleDateFormat simpleDateFormat;
    String Date;

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

//        textClock = (TextClock) findViewById(R.id.textClock);
//        textClock.setFormat12Hour("hh:mm:ss aa");
//        String time = textClock.getText().toString();

        textView     = (TextView) findViewById(R.id.textView);
        textView2     = (TextView) findViewById(R.id.textView2);
        button     = (Button) findViewById(R.id.button);
                                                                                                     //Showing current time
        calendar = Calendar.getInstance();
        simpleDateFormat= new SimpleDateFormat("dd-MM-yyyy HH:mm");
        Date = simpleDateFormat.format(calendar.getTime());
        textView.setText(Date);


        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                Calendar c = Calendar.getInstance();

                int year = c.get(Calendar.YEAR);
                int month = c.get(Calendar.MONTH);
                int day = c.get(Calendar.DAY_OF_MONTH);

                DatePickerDialog datePickerDialog = new DatePickerDialog(MainActivity.this, MainActivity.this, year, month, day);
                datePickerDialog.show();
            }
        });


    }


    @Override
    public void onDateSet(DatePicker datePicker, int i, int i1, int i2) {

        int yearFinal = i;
        int monthFinal = i1+1;
        int dayFinal = i2;

        Calendar c = Calendar.getInstance();
        int hour = c.get(Calendar.HOUR_OF_DAY);
        int minute = c.get(Calendar.MINUTE);

        TimePickerDialog timePickerDialog = new TimePickerDialog( MainActivity.this,
                MainActivity.this, hour, minute);
        timePickerDialog.show();


    }

    @Override
    public void onTimeSet(TimePicker timePicker, int i, int i1) {

        hourFinal = i;
        minuteFinal = i1;

        textView2.setText(earFinal + monthFinal + dayFinal + hourFinal + minuteFinal);



    }
}

Answer 1

  boolean isRunning = false;

  private void showHandler() {

        Toast.makeText(getApplicationContext(), "please wait 30 second", Toast.LENGTH_SHORT).show();

        countDownTimer = new CountDownTimer(30000, 1000) {

            public void onTick(long millisUntilFinished) {
                isRunning = true;

            }

            public void onFinish() {
                isRunning = false;

            }

        }.start();
    }

Please try this code.It may help you.

Answer 2

You can calculate time difference between current date and user picked date in milliseconds.

    private long getTimeDelay(Calendar userPickedTime){
        return userPickedTime.getTimeInMillis() - Calendar.getInstance().getTimeInMillis(); // Time difference 
    }

Then you can schedule a timer to perform an action at that time.

new Timer().schedule(new TimerTask() {          
    @Override
    public void run() {
        // this code will be executed after time difference between current and user picked time.        
    }
}, getTimeDelay(userPickedTime));