Monday, May 6, 2013

ActionBarSherlock configuration

I'm creating a custom Theme, let's call it TestABS with parent the HOLO Theme ( in our case Sherlock ).
So now in my styles.xml I add the line :
<style name="Theme.TestABS" parent="@style/Theme.Sherlock"></style> 

Later I'll edit Manifest file like this :


When Activity starts, the system adds ActionBar and the overflow menu by calling onCreateOptionsMenu().
This method inflates an XML resource which defines the menu items. This files is in the folder /res/menu. In those items on the XML file I have to add the android:showAsAction keyword, so now the items will appear as Action Items in my ActionBar and not Options Menu.

So a simple item should be like :

        android:title="Text Here" />

This works as long as I have an ActionBar in my Activity( When do I have an ActionBar ? When I add   android:theme="@style/Theme.HOLO" in my manifest file for android 3.0 and greater. For lower versions I need Theme.Sherlock . In both cases I can declare mine custom theme like I did above with TestABS ).

Links :
1) Adding ActionBarSherlock to your Project
2) Adding Items to the ActionBar 
3) The Overflow menu ( As a rule of thumb you should always use ifRoom, if you want the icon to be part of your action bar and you should use never if you want the item to always be part of the overflow menu. )

Wednesday, April 10, 2013

Add Marker to Google Map

To detect a long map click by the user, so add a new Marker, we need to implement OnMapLongClickListener Interface.

Then we set our map to listen for any calls when its long pressed :    mMap.setOnMapLongClickListener(this);

And now in our code we can add a new Marker every time the user long clicks the map :

mMap.addMarker(new MarkerOptions().position(point));

Monday, April 8, 2013

Detect user click on Map

To detect click on GoogleMap we implement OnMapClickListener Interface.
We add to our GoogleMap setOnMapClickListener . This sets a callback to the Interface when the map is clicked

Then we need to override the onMapClick(LatLng point) 

public void onMapClick(LatLng point) { mMap.animateCamera(CameraUpdateFactory.newLatLng(point)); }

We are using CameraUpdateFactory to get a new CameraUpdate Object ( an object to modify a map's camera ) and animate to the new point with animateCamera.

Sunday, April 7, 2013

Display my Location - Google maps API V2

All we need to do is to use the method setMyLocationEnabled(boolean enabled) which enables the my-Location layer.
Like that :

private GoogleMap mMap;

Sunday, February 17, 2013

Fragments Tutorial - Simple 2 - Passing Data

Passing Data between Fragment and host Activity

To pass data from a Fragment to the host Activity we need to Define/declare an Interface and
Implement it on the Activity.

1. Declare an Interface on Fragment_A. 

public interface OnSomethingSelectedListener {
    public void passData(int position);

2. onAttach() : To be sure that Activity implements the Interface  onAttach callback method of Fragment_A  we instantiate an Instance of Ιnterface by casting the Activity  passed into onAttach().
The Fragment captures the interface implementation during its onAttach() lifecycle method and can then call the Interface methods in order to communicate with the Activity.

    public void onAttach(Activity activity) {
        // This makes sure that the container activity has implemented the callback interface. If not, it throws an exception
        try {
            listener = (OnSomethingSelectedListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement OnHeadlineSelectedListener");

3. On Main Activity we implement the Interface like this :

public class MainActivity extends FragmentActivity implements OnSomethingSelectedListener

public void passData(int position) {
 Log.d(TAG, "Give me the result  " + position  );
 position = position +1;
 Log.d(TAG, "Give me the result  " + position  ); 

We just take the integer value parameter from the Fragment and add one to it.

4. A button on Fragment's layout so we can add onClick event

android:text="send Integer">

5. And on Fragment's onCreateView() we add the listener for the event:
Button button = (Button) view.findViewById(;
    button.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            Log.v(TAG, "onClick 1");
            listener.passData(5); //pass an Integer
We pass the value five to the method passData() Now when we click on the Button we open LogCat View and we see that value one has been added to the  value  of the parameter:

Wednesday, February 13, 2013

Fragments Simple Example - Version 1

We will make an Activity that will display 2 fragments in its layout.
One fragment will be above the other just like the screen. Both fragments will be of the TextView type and will display text.

So here is what we 're going to have:

Where in the above image is shown the TextView that we are going to define in the layout for Fragment A and respectively down the TextView in layout for Fragment B.

public class Fragment_A extends Fragment {

  public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

          return inflater.inflate(R.layout.fragment_a_layout, container, false);

and the fragment_a_layout as we said is a TextView :
    android:text="Fragment A">
Respectively we make up the class for the Fragment B and layout as fragment_a_layout. Now what's left is to bind the 2 fragments on Activity's layout.

<RelativeLayout xmlns:android=""
    tools:context=".MainLayoutActivity" >

          android:layout_marginBottom="20dp" />

          android:layout_below="@id/id_frag_A" />


What you must take care is that we use RelativeLayout because its much more dynamic and flexible than LinearLayout and thats something we are going to need for the next Fragment Tutorials.
Also every <fragment> element has its own name, ie for Fragment A we call it as android:name="org.example.fragmentsapp.Fragment_A" and the same for B. Later when we are going to use them inside the Activity scope that will be based on the id we have define.

So our Activity is :
package org.example.fragmentsapp;

import android.os.Bundle;

public class MainLayoutActivity extends FragmentActivity {

	protected void onCreate(Bundle savedInstanceState) {

Keep in mind that we refer also to APIs lower than API 11 so we extend FragmentActivity and not Activity.
If you target device with android 3.0 or later then you can change FragmentActivity with Activity.

FragmentActivity is something that we can use because of the  Support library

Tuesday, November 27, 2012

No enclosing instance of type First is accessible.

Error :  "No enclosing instance of type First is accessible. Must qualify the allocation with an enclosing instance of type First "

Solution: You cannot instantiate a non-static inner class from a static context like main.