Question

This little thing started to frustrate me a lot. I thought it was something simle to do, but I think I haven’t understood clearly how android works.

Anyway, the problem is that my android application will have some buttons that will open a date or time picker dialog box when pressed. I know how to implement them directly in the same class as the main activity itself, but I don’t think that’s good solution for maintenance reasons and also if I’m going to develop that application further some day.

I tried to do this by several different ways and failed every time I tried to do it. That left me pretty clueless of what to do and what’s the problem.

Here’s one way I tried to do this:

the main activity (I simplified it and tried to provide only the necessary code, because it’s long). This is following the singleton design pattern.

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    dateButton = (Button) findViewById(R.id.editDateButton);

    dateButton.setOnClickListener(this);
}

@Override
public void onClick(View view) {
    if(view.getId() == R.id.editStartDateButton) {
        DatePickers.getInstance().setDate(dateButton);
    }
}

The date pickers class (extends Activity; also simplified code and all the unnecessary things removed):

private static DatePickers self = null;

public static DatePickers getInstance() {
    if (null == self) {
        self = new DatePickers();
    }
    return self;
}

public void setDate(Button button) {
    theButtonUsed = button;
    showDialog(DATE_DIALOG_ID);
}

After the showDialog call the class is similar to the example Hello-DatePicker in android developer site.

Also I tried to do it pretty much like in here, but with the differnece that when the dateButton is clicked it starts the new activity that’s the date picker dialog. In this case the datePicker class was like this:

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.datePicker);

    showDialog(DATE_DIALOG_ID);
}

And the rest as it is in the Hello-DatePicker example in android dev site. Both these solutions lead to a problem where my application crashed and was forced to quit.

I hope you understand what’s the problem and that you could guide me and show what I’m doing wrong. I tried to make this short and provide only the necessary information.

Thanks
-Z

Edit:

As I have mentioned in one of the comments, the real problem with this was that I has simply forgotten to add the new activity to the manifest file. There might have been some other problems that was solved with the accepted answer. I hope this is still helpful to anyone facing similar issues.

Answer 1

I think I can help you out there.

I know my solution isn’t going to follow your singleton approach but it definitely separates DatePicker code from the calling Activity or Activities – which in return becomes modular and clean.

So here it goes:
Below is the designated DatePicker code (I named it DateSelector). You start this activityForResult and it will return a bundle with Day, Month, and Year to the calling Activity.

I’m also going to pasting the simple layout DateSelector uses right below it; it’s just a transparent layout…

package com.cyberfabric.historicise.activities;

import java.util.Calendar;

import com.cyberfabric.historicise.R;
import android.app.Activity;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.content.Intent;
import android.os.Bundle;

import android.view.Window;


public class DateSelector extends Activity{

    private final static int DIALOG_DATE_PICKER = 0;

    private int setYear;
    private int setMonth;
    private int setDay;


    @Override
    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        getWindow().requestFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.date_picker);

        Calendar today = Calendar.getInstance();
        setYear = today.get(Calendar.YEAR);
        setMonth = today.get(Calendar.MONDAY);
        setDay = today.get(Calendar.DAY_OF_MONTH);

        showDialog(DIALOG_DATE_PICKER); 
    }

    @Override
    protected Dialog onCreateDialog(int id){
        switch(id){
            case DIALOG_DATE_PICKER:
                return new DatePickerDialog(this, mDateSetListener, setYear, setMonth, setDay);
            }
        return null;
    }

    private DatePickerDialog.OnDateSetListener mDateSetListener = new DatePickerDialog.OnDateSetListener(){
        @Override
        public void onDateSet(android.widget.DatePicker view, int year, int month, int day) {
            setYear = year;
            setMonth = month;
            setDay = day;
            returnDate();
        }
    };


    /*
     * Package up the data and return it back to the calling intent
     */
    private void returnDate(){
        Intent intent = getIntent();    // calling/parent intent //

        Bundle bundle = new Bundle();
        bundle.putInt("year", setYear);
        bundle.putInt("month", setMonth);
        bundle.putInt("day", setDay);
        intent.putExtra("set_date", bundle);

        setResult(Activity.RESULT_OK, intent);

        finish();
    }
}  

Here is the layout DateSelector uses:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@color/transparent"
    />

Your calling Activity or Activities should launch DateSelector as such:

// some global variable declared in order to start activityForResult and to catch 
// it back on onActivityResult
private final static int REQUEST_GET_DATE = 3;

Starting the DateSelector from the calling Activity:

Intent dp = new Intent(EventForm.this, DateSelector.class);
EventForm.this.startActivityForResult(dp, REQUEST_GET_DATE);

And finally in your calling Activity just catch it onActivityResult:

protected void onActivityResult(int requestCode, int resultCode, Intent data){ 
    super.onActivityResult(requestCode, resultCode, data); 

    switch(requestCode){ 
        case REQUEST_GET_DATE:
            if(resultCode == Activity.RESULT_OK){
                Bundle setDate = data.getBundleExtra("set_date");
                int setDay = setDate.getInt("day");
                int setMonth = setDate.getInt("month");
                int setYear = setDate.getInt("year");
                System.out.println(setDay + " " + setMonth + " " + setYear);
            }
            break;
    }
}

I hope this helps, hope you like it,

Best,

-serkan