On `API &lt; 11` use `supportInvalidateOptionsMenu()` method

`ActivityCompat.invalidateOptionsMenu()` doesn&#39;t callback `onPrepareOptionsMenu();` it just update the menu directly. Just put some `Log.d()` and check out by yourself.

This works for me (I&#39;m using API 8):

        	
    private Menu mMenu;
    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    	inflater.inflate(R.menu.track_fragment, menu);
    	mMenu = menu;
        }
    ...
    private void someMethod() {
    ...
        if (mMenu != null) {
    	   MenuItem item = mMenu.findItem(R.id.new_track);
    	   if (item != null) {
      	        item.setVisible(false);
                ActivityCompat.invalidateOptionsMenu(this.getActivity());
    	    }
    	}
    ...
    }

My `someMethod()` get called from several places, even before `onCreateOptionsMenu()`, so I must check `mMenu != null`.


This will return true if the API is above or equal to 11 and therefore supported. Before API 11, the menu is drawn when the menu button is pressed so there is no need for this method as it occurs automatically.

I&#39;m writing a password verify directive :


 
     Directives.directive(&quot;passwordVerify&quot;,function(){
        return {
            require:&quot;ngModel&quot;,
            link: function(scope,element,attrs,ctrl){
                ctrl.$parsers.unshift(function(viewValue){
                    var origin = scope.$eval(attrs[&quot;passwordVerify&quot;]);
                    if(origin!==viewValue){
                        ctrl.$setValidity(&quot;passwordVerify&quot;,false);
                        return undefined;
                    }else{
                        ctrl.$setValidity(&quot;passwordVerify&quot;,true);
                        return viewValue;
                    }
                });
    
            }
        };
    });

html :

    

    &lt;input data-ng-model=&#39;user.password&#39; type=&quot;password&quot; name=&#39;password&#39; placeholder=&#39;password&#39; required&gt;
    &lt;input data-ng-model=&#39;user.password_verify&#39; type=&quot;password&quot; name=&#39;confirm_password&#39; placeholder=&#39;confirm password&#39; required data-password-verify=&quot;user.password&quot;&gt;


Given 2 password fields in a form, if both password values are equal then the field affected  by the directive is valid.
The issue is that it works one way (i.e. when I type a password in the password-verify field). However, when the original password field is updated, the password-verify doesn&#39;t become valid. 

Any idea how I could have a &quot;two way binding verify?&quot;

password-check directive in angularjs

&gt; **Possible Duplicate:**  
&gt; [How can I check whether a variable is defined in JavaScript?](https://stackoverflow.com/questions/519145/how-can-i-check-whether-a-variable-is-defined-in-javascript)  
&gt; [Is there a standard function to check for null, undefined, or blank variables in JavaScript?](https://stackoverflow.com/questions/5515310/is-there-a-standard-function-to-check-for-null-undefined-or-blank-variables-in)  

&lt;!-- End of automatically inserted text --&gt;

I have a script that occurs in two parts.

The first part sets up a var:


    var pagetype = &quot;textpage&quot;;

The 2nd part is a simple if statement:

    if(pagetype == &quot;textpage&quot;) {
    //do something
    };

Now the 2nd part, the if statement, appears on all pages of my site. But the first part, where the var is declared, only appears on some of my pages.

On the pages without the var I naturally get this error:

    Uncaught ReferenceError: pagetype is not defined

So my question is: is there a way with JavaScript or JQ to detect if a var exists at all (not just if it has data assigned to it)?

I am imagining I would just use another if statment, eg:

    if (&quot;a var called pagetypes exists&quot;)....

JQuery/Javascript: check if var exists

I used `ActivityCompat.invalidateOptionsMenu(MainActivity.this);` so that my menu item &quot;refresh&quot;  can automatically be enabled/disabled without the using have to touch the &quot;Menu&quot; option (imagine the user leaves the Menu open... I need the &quot;Refresh&quot; menu item to automatically disabled and enable itself). 

The `ActivityCompat.invalidateOptionsMenu(MainActivity.this)` works fine in Android 11+. But what can I use for android API &lt; 11 ? :S I&#39;ve searched so much but I cannot find an answer. Can anyone please help me on this? 

This works fine in Android API 11+, using the `onPrepareOptionsMenu` and `ActivityCompat.invalidateOptionsMenu(MainActivity.this)`. 
The issue is trying to get it done in Android API &lt; 11.

Here is my `onPrepareOptionsMenu` method: 

	@Override
	public boolean onPrepareOptionsMenu(Menu menu) {
		if(menuRefreshEnable){
			menu.getItem(0).setEnabled(true);
		}
		if(!menuRefreshEnable){
			menu.getItem(0).setEnabled(false);
		}		
		return true;
	}

Android invalidateOptionsMenu() for API &lt; 11

I used <code>ActivityCompat.invalidateOptionsMenu(MainActivity.this);</code> so that my menu item "refresh" can automatically be enabled/disabled without the using have to touch the "Menu" option (imagine the user leaves the Menu open... I need the "Refresh" menu item to automatically disabled and enable itself).
The <code>ActivityCompat.invalidateOptionsMenu(MainActivity.this)</code> works fine in Android 11+. But what can I use for android API &#x3C; 11 ? :S I've searched so much but I cannot find an answer. Can anyone please help me on this?
This works fine in Android API 11+, using the <code>onPrepareOptionsMenu</code> and <code>ActivityCompat.invalidateOptionsMenu(MainActivity.this)</code>.
The issue is trying to get it done in Android API &#x3C; 11.
Here is my <code>onPrepareOptionsMenu</code> method:
<pre><code class="hljs language-scss">@Override
public boolean onPrepareOptionsMenu(Menu menu) {
	if(menuRefreshEnable){
		menu.getItem(0).setEnabled(true);
	}
	if(!menuRefreshEnable){
		menu.getItem(0).setEnabled(false);
	}		
	return true;
}
</code></pre>

I&#39;m connecting a webcam to my emulator by setting the front camera to &quot;webcam0&quot; in the AVD Manager.  When I start the emulator&#39;s camera application, I get the error

    CameraService::connect X (pid 702) rejected (invalid cameraId 0).

Here&#39;s the relevant portion of the Android source code:

    sp&lt;ICamera&gt; CameraService::connect(
        const sp&lt;ICameraClient&gt;&amp; cameraClient, int cameraId) {

        int callingPid = getCallingPid();

        [...]

        if (cameraId &lt; 0 || cameraId &gt;= mNumberOfCameras) {
            LOGE(&quot;CameraService::connect X (pid %d) rejected (invalid cameraId %d).&quot;,
                callingPid, cameraId);
            return NULL;
        }

        [...]
    }

The webcam has been correctly assigned an ID of 0 because there&#39;s only 1 camera. However, `mNumberOfCameras` is presumably still 0.  This means that the camera is being registered by the emulator, but it hasn&#39;t bothered to update the number of connected cameras.  

**How can I connect a webcam so that it will be properly recognized by the emulator?**

Edit: the command `emulator -webcam-list -avd &lt;name of your AVD&gt;` in `\android-sdks\tools` gives the result:

    List of web cameras connected to the computer:
    Camera `webcam0` is connected to device `AndroidEmulatorVC0` on channel 0 using pixel format `BGR4`

When I launch the webcam from Eclipse&#39;s AVD manager or using `emulator -camera-front webcam0 -avd &lt;name of your AVD&gt;`, I get the following window: 

![enter image description here][1]

Edit 2: This seems to be a bug in the emulator. The suggested answer tells you what to do to set up the camera, but doesn&#39;t solve the problem for me.  I ultimately solved it by using a laptop with a built-in webcam.  Perhaps another USB webcam might have worked as well.

  [1]: http://i.stack.imgur.com/Y7Suc.png

Android: How to use webcam in emulator?

I can&#39;t find an example on how to intercept the map touch on the new Google Maps API v2.

I need to know when the user touches the map in order to stop a thread (the centering of the map around my current location).


Google Maps Android API v2 - detect touch on map

This is a button selector such that when normal it appears red, when pressed it appears grey.

I would like to ask how could the code be further directly modified such that when PRESSED the text size and color could also change? Many thanks!


&lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot;?&gt;
&lt;selector xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;&gt;

    &lt;item android:state_pressed=&quot;true&quot; &gt;         
        &lt;shape xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;&gt; 
            &lt;stroke android:width=&quot;2dp&quot; android:color=&quot;@color/black&quot; /&gt;
            &lt;solid android:color=&quot;@color/grey&quot;/&gt;
            &lt;padding android:left=&quot;5dp&quot; android:top=&quot;2dp&quot; 
                android:right=&quot;5dp&quot; android:bottom=&quot;2dp&quot; /&gt; 
            &lt;corners android:radius=&quot;5dp&quot; /&gt; 
        &lt;/shape&gt;    
    &lt;/item&gt;

    &lt;item&gt;
        &lt;shape xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;&gt; 
            &lt;stroke android:width=&quot;2dp&quot; android:color=&quot;@color/black&quot; /&gt;
            &lt;solid android:color=&quot;#FF6699&quot;/&gt;
            &lt;padding android:left=&quot;5dp&quot; android:top=&quot;2dp&quot; 
                android:right=&quot;5dp&quot; android:bottom=&quot;2dp&quot; /&gt; 
            &lt;corners android:radius=&quot;5dp&quot; /&gt; 
        &lt;/shape&gt;
    &lt;/item&gt;

&lt;/selector&gt;
 	

android button selector

I&#39;m trying to store a set of strings using the [`SharedPreferences` API][1].

    Set&lt;String&gt; s = sharedPrefs.getStringSet(&quot;key&quot;, new HashSet&lt;String&gt;());
    s.add(new_element);
    
    SharedPreferences.Editor editor = sharedPrefs.edit();
    editor.putStringSet(s);
    edit.commit()

The first time I execute the code above, `s` is set to the default value (the just created end empty `HashSet`) and it is stored without problems.

The second and next times I execute this code, a `s` object is returned with the first element added. I can add the element, and during the program execution, it is apparently stored in the `SharedPreferences`, but when the program is killed, the `SharedPreferences` read again from its persistent storage and the newer values are lost.

How can the second, and elements after that, be stored so they won&#39;t get lost?

  [1]: http://developer.android.com/reference/android/content/SharedPreferences.html
  [2]: http://developer.android.com/reference/android/content/SharedPreferences.html#getStringSet%28java.lang.String,%20java.util.Set%3Cjava.lang.String%3E%29

Misbehavior when trying to store a string set using SharedPreferences

I have problem making my fragments communicating with each other through the `Activity`, which is using the `FragmentPagerAdapter`, as a helper class that implements the management of tabs and all details of connecting a `ViewPager` with associated `TabHost`. I have implemented `FragmentPagerAdapter` just as same as it is provided by the Android sample project *Support4Demos*.

The main question is how can I get particular fragment from `FragmentManager` when I don&#39;t have neither Id or Tag? `FragmentPagerAdapter` is creating the fragments and auto generating the Id and Tags.



How to get existing fragments when using FragmentPagerAdapter

I&#39;m trying to create a simple menu with one button that will call a method to clear the array. I don&#39;t want to use xml because all I need is one button.

Something like this -

    public boolean onCreateOptionsMenu(Menu menu) {
        button &quot;Clear Array&quot;;
        onClick{// run method that wipes array};
        return true;
    }

Thank you

Android Create a simple menu programmatically

I&#39;ve been searching around trying to figure out how to create a popup or a dialog that has 4 options to choose from.

 I see this picture on the Android developer site: 

![enter image description here][1]

Does anyone know how to code up something like the one on the right? I don&#39;t need any icons next to my text, I just need to be able to select from 4 options.


  [1]: http://i.stack.imgur.com/Ywkgq.png

Android: create a popup that has multiple selection options

I have a list view connected to a database, showing a all the entries. I want a menu to show up if the user long clicks a item in the listview(database entry), showing options to edit or delete the entry. how can i do this. 

Till now, I have tried using a onItemLongClick listener and a toast in it showing the id of the view long clicked.

    @Override
	public boolean onItemLongClick(AdapterView&lt;?&gt; parent, View view,
			int position, long id) {

		String res = Long.toString(id);
		 Toast toast = Toast.makeText(this, res, Toast.LENGTH_SHORT);
		 toast.show();

		return true;
	}

creating a menu after a long click event on a list view

How do I do a custom dropdown/popup menu anchored to a button?

I need it to work like the popup menu (anchored to a view), and do something when I click an item from the menu. 

How do I add items to the menu by code, keeping menu&#39;s height and make it scrollable if there are more than 5 items. I don&#39;t need to add any images, just text.

![enter image description here][1]


  [1]: http://i.stack.imgur.com/eGciL.png

Android custom dropdown/popup menu

Since I implented app compat my searchview doesn&#39;t work anymore:

     Process: com.laurenswuyts.witpa, PID: 26666
        java.lang.NullPointerException: Attempt to invoke virtual method &#39;void android.support.v7.widget.SearchView.setSearchableInfo(android.app.SearchableInfo)&#39; on a null object reference
                at com.laurenswuyts.witpa.Activities.Events.EventActivity.onCreateOptionsMenu(EventActivity.java:75)
                at android.app.Activity.onCreatePanelMenu(Activity.java:2820)
                at android.support.v4.app.FragmentActivity.onCreatePanelMenu(FragmentActivity.java:275)
                at android.support.v7.app.ActionBarActivity.superOnCreatePanelMenu(ActionBarActivity.java:276)
                at android.support.v7.app.ActionBarActivityDelegate$1.onCreatePanelMenu(ActionBarActivityDelegate.java:79)
                at android.support.v7.widget.WindowCallbackWrapper.onCreatePanelMenu(WindowCallbackWrapper.java:49)
                at android.support.v7.internal.app.ToolbarActionBar.populateOptionsMenu(ToolbarActionBar.java:459)
                at android.support.v7.internal.app.ToolbarActionBar$1.run(ToolbarActionBar.java:69)
                at android.os.Handler.handleCallback(Handler.java:739)
                at android.os.Handler.dispatchMessage(Handler.java:95)
                at android.os.Looper.loop(Looper.java:135)
                at android.app.ActivityThread.main(ActivityThread.java:5221)
                at java.lang.reflect.Method.invoke(Native Method)
                at java.lang.reflect.Method.invoke(Method.java:372)
                at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
                at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

So nullpointer for searchview while I have it:
    
    @Override
        public boolean onCreateOptionsMenu(Menu menu) {
            MenuInflater inflater = getMenuInflater();
            inflater.inflate(R.menu.event_main, menu);
    
            // Get the SearchView and set the searchable configuration
            // Associate searchable configuration with the SearchView
            SearchManager searchManager =
                    (SearchManager) getSystemService(Context.SEARCH_SERVICE);
            SearchView searchView =
                    (SearchView) menu.findItem(R.id.action_search).getActionView();
            searchView.setSearchableInfo(
                    searchManager.getSearchableInfo(getComponentName()));
    
    
            return super.onCreateOptionsMenu(menu);
        }

And in my menu I have this:

    &lt;!-- Search Widget --&gt;
      &lt;item android:id=&quot;@+id/action_search&quot;
          android:title=&quot;@string/action_search&quot;
          android:icon=&quot;@drawable/ic_action_search&quot;
          app:showAsAction=&quot;always&quot;
          android:actionViewClass=&quot;android.support.v7.widget.SearchView&quot;/&gt;

I have no idea why it doesn&#39;t work anymore but it happened since I started using app compat 21.

Regards,

Content Type	Original Author	Original Content on Stackoverflow
Question	SnitramSD	View Question on Stackoverflow
Solution 1 - Android	Alexander Zhak	View Answer on Stackoverflow
Solution 2 - Android	user2461595	View Answer on Stackoverflow
Solution 3 - Android	AndroidPenguin	View Answer on Stackoverflow

Android invalidateOptionsMenu() for API < 11

Android Problem Overview

Android Solutions

Solution 1 - Android

Solution 2 - Android

Solution 3 - Android

JQuery/Javascript: check if var exists

password-check directive in angularjs

Attributions