Item with app:showAsAction not showing

Things you should always check when you want to use action bar are

1) Extend ActionBarActivity instead of Activity

public class MainMenu extends ActionBarActivity{

2) Have the right style selected as defined at manifest

Manifest

<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >

Style

    <style name="AppTheme"
    parent="Theme.AppCompat.Light.DarkActionBar">
    </style>

3) Select the right title for showAsAction

  <menu xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:**yourapp**="http://schemas.android.com/apk/res-auto" >
  <item android:id="@+id/action_search"
      android:icon="@drawable/ic_action_search"
      android:title="@string/action_search"
      **yourapp**:showAsAction="ifRoom"  />
    ...
  </menu>

This is what most people get wrong

4) Define your Menu in Activity

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu items for use in the action bar
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.main_activity_actions, menu);
    return super.onCreateOptionsMenu(menu);
}

If you do all the following your action bar should work.

Then you should add the onClickListener for every position…