Android: animate searchview
<p>I'm trying to implement an animated searchview (with a simple extend/collapse animation) but all the answers in this forum are not working.</p>

<pre><code>&lt;item
    android:id="@+id/action_search"
    android:orderInCategory="100"
    android:title="@string/action_search"
    app:actionViewClass="android.support.v7.widget.SearchView"
    android:icon="@drawable/ic_search_white_48px"
    app:showAsAction="always"/&gt;
</code></pre>

<p>what i've done</p>

<pre><code>@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    SearchView searchView = (SearchView) menu.findItem(R.id.action_search).getActionView();
    //Get the ID for the search bar LinearLayout
    int searchBarId = searchView.getContext().getResources().getIdentifier("android:id/search_bar", null, null);
    //Get the search bar Linearlayout
    LinearLayout searchBar = (LinearLayout) 
            searchView.findViewById(searchBarId);
    //Give the Linearlayout a transition animation.
    searchBar.setLayoutTransition(new LayoutTransition());
    return true;
}
</code></pre>

<p>all the error:</p>

<pre><code>E/AndroidRuntime: FATAL EXCEPTION: main
              Process: com.daveslab.wideview, PID: 2459
              java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.LinearLayout.setLayoutTransition(android.animation.LayoutTransition)' on a null object reference
                  at com.daveslab.wideview.MainActivity.onCreateOptionsMenu(MainActivity.java:69)
                  at android.app.Activity.onCreatePanelMenu(Activity.java:2846)
                  at android.support.v4.app.FragmentActivity.onCreatePanelMenu(FragmentActivity.java:360)
                  at android.support.v7.view.WindowCallbackWrapper.onCreatePanelMenu(WindowCallbackWrapper.java:88)
                  at android.support.v7.app.AppCompatDelegateImplBase$AppCompatWindowCallbackBase.onCreatePanelMenu(AppCompatDelegateImplBase.java:331)
                  at android.support.v7.view.WindowCallbackWrapper.onCreatePanelMenu(WindowCallbackWrapper.java:88)
                  at android.support.v7.app.ToolbarActionBar.populateOptionsMenu(ToolbarActionBar.java:454)
                  at android.support.v7.app.ToolbarActionBar$1.run(ToolbarActionBar.java:61)
                  at android.os.Handler.handleCallback(Handler.java:739)
                  at android.os.Handler.dispatchMessage(Handler.java:95)
                  at android.os.Looper.loop(Looper.java:148)
                  at android.app.ActivityThread.main(ActivityThread.java:5417)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
</code></pre>

<p>errors in values.xml(all the icons are in the project with the correct name):</p>

<pre><code>Error:(1605, 21) No resource found that matches the given name: attr 'searchBackIcon'.
</code></pre>

<p>Error:(1602, 21) No resource found that matches the given name: attr 'searchBackground'.
Error:(1604, 21) No resource found that matches the given name: attr 'searchCloseIcon'.
Error:(1606, 21) No resource found that matches the given name: attr 'searchSuggestionBackground'.
Error:(1603, 21) No resource found that matches the given name: attr 'searchVoiceIcon'.
Error:(1605, 21) No resource found that matches the given name: attr 'searchBackIcon'.
Error:(1602, 21) No resource found that matches the given name: attr 'searchBackground'.
Error:(1604, 21) No resource found that matches the given name: attr 'searchCloseIcon'.
Error:(1606, 21) No resource found that matches the given name: attr 'searchSuggestionBackground'.
Error:(1603, 21) No resource found that matches the given name: attr 'searchVoiceIcon'.
Error:Execution failed for task ':app:processDebugResources'.
com.android.ide.common.process.ProcessException: Failed to execute aapt.</p>