How to Get Actionbar View

How to get ActionBar view?

Yep. You can actually get the view by using this function:

public View getActionBarView() {
    Window window = getWindow();
    View v = window.getDecorView();
    int resId = getResources().getIdentifier("action_bar_container", "id", "android");
    return v.findViewById(resId);
}

Pretty much the way this works is that the actionbar container uses the id android.R.id.action_bar_container, but this id is not public. Therefore we use getIdentifier() to retrieve this id and then the rest is simple.

how to get action bar?

First of all, you will only use getSupportActionBar() if your activity is extending an ActionBarActivity, so in your case, you must use getActionBar() like you did. The problem could be in your Theme. Make sure in your AndroidManifest.xml if you aren't using something such as android:theme="@android:style/Theme.Holo.Light.NoActionBar", because it can cause nullexception.
In Addition to what you have done, you need to add

getActionBar().setHomeButtonEnabled(true);

before

getActionBar().setDisplayHomeAsUpEnabled(true);

Get ActionBar TextView (title) in android

All of the built-in Android layouts can be found in the SDK under:

.../android-sdk/platforms/android-<API-VERSION>/data/res/layout/

I think the one you are looking for in this case is action_bar_title_item.xml.

This is v19's:

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (C) 2010 The Android Open Source Project

     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
     You may obtain a copy of the License at

          http://www.apache.org/licenses/LICENSE-2.0

     Unless required by applicable law or agreed to in writing, software
     distributed under the License is distributed on an "AS IS" BASIS,
     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     See the License for the specific language governing permissions and
     limitations under the License.
-->

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_gravity="center_vertical|start"
              android:orientation="vertical"
              android:paddingEnd="8dp">
    <TextView android:id="@+id/action_bar_title"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:singleLine="true"
              android:ellipsize="end" />
    <TextView android:id="@+id/action_bar_subtitle"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_marginTop="@dimen/action_bar_subtitle_top_margin"
              android:singleLine="true"
              android:ellipsize="end"
              android:visibility="gone" />
</LinearLayout>

Layouts can and do differ between API versions. In general the IDs will match but I can't say this would be true for every single layout and will always be so it's best to quickly look at each for differences if you are planning to use specific built in resources like this in case.

To do that, you will have to grab individual copies of the source code to look at each API version.

This can either be done though:

Your IDE: use Android's ADT plugin for your IDE of choice (Eclipse or AndroidStudio)
Manual method: calling the SDK's version yourself which is located within the SDK at:
.../android-sdk/tools/android

You obviously need only grab the versions you are supporting and as I mentioned above each will have its own folder named after its single int version number. Eg:

.../android-sdk/platforms/android-19/data/res/layout/action_bar_title_item.xml
.../android-sdk/platforms/android-15/data/res/layout/action_bar_title_item.xml
.../android-sdk/platforms/android-11/data/res/layout/action_bar_title_item.xml
.../android-sdk/platforms/android-10/data/res/layout/???

Uh-oh! No layout for API-10. If you want to use the action_bar_title_item.xml layout in that version of the API you can include and use Sherlock ActionBar or perhaps copy or modify the v11 layout to:

.../YourApp/res/layout-v10/action_bar_title_item.xml               (Eclipse)
.../YourApp/app/src/main/res/layout-v10/action_bar_title_item.xml  (Android Studio)

Your call. The same can be done it you just want to customise the layout. Copy the android built in version to your own layout folders and tweak to your heart's content. Just be mindful of what folders you place the files in so that they are overriding the desired, correct versions.

Android get a View reference to action bar item?

You can do menu.findItem(R.id.youritemid) to get the menu item, and you can get reference to menu object in your onCreateOptionsMenu(Menu menu) method then you can initialize a global variable with that menu object to use it anywhere.

Here is some code:

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.main, menu);
    _menu = menu;
    return true;
}

I am initialize my global variable Menu _menu; with menu object and then i can do like this MenuItem mi = _menu.findItem(R.id.itemid); any where i want.

Edit:
Please take care that you are not calling anything on menuitem before the menu gets created, you can schedule a thread to wait for 3 to 5 secs or you can do it some other way, all you should worry about is whether the menu has been initialized or not.

How access ActionBar from fragment on Android

Override your onAttach(Activity), then cast your Activity to ActionBarActivity, the you can get an ActionBar.
Like:

@Override
public void onAttach(Activity activity) {
    // TODO Auto-generated method stub
    super.onAttach(activity);
    ActionBar actionBar=((ActionBarActivity)activity).getSupportActionBar();
}

How to show a custom actionbar view from one fragment only

For this issue, only show actionbar for one fragment without show on all other fragments, solution could be very easy:

In your activity that hosts your fragments:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ... ...

    // for API >= 11
    getActionBar.hide();
    // for API < 11
    getSupportActionBar().hide();

    ... ...
}

Then in the fragment that you want to show actionbar:

@Override
public void  onAttach(Activity activity){
    activity.getActionBar().show(); //getSupportActionBar() for API<11

}

@Override
public void onHiddenChanged(boolean hidden) {
    super.onHiddenChanged(hidden);
    if (hidden) {
       getActivity().getActionBar().hide(); //getSupportActionBar() for API<11
    } else {
       getActivity().getActionBar().show(); //getSupportActionBar() for API<11
}

}

Get item view from ActionBar

As it has been said here and here, getActionView returns the view that we sets in setActionView. Therefore, the only one way to customize action bar menu item described here

How to get action bar title as TextView in AppCompat?

Typically when using the Toolbar in my cases, if I am doing something custom with the title, I will just inflate the title view manually, then set its attributes in XML. The point of Toolbar is to prevent things like this from happening, so you can have more control over what your toolbar looks like

<android.support.v7.widget.Toolbar
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/my_awesome_toolbar"
    android:layout_height="@dimen/standard_vertical_increment"
    android:layout_width="match_parent"
    android:minHeight="@dimen/standard_vertical_increment"
    android:background="@drawable/actionbar_background">

    <TextView
        style="@style/TextAppearance.AppCompat.Widget.ActionBar.Title"
        android:id="@+id/toolbar_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="@color/Red" />

</android.support.v7.widget.Toolbar>

Then in code, you would do something like this:

Toolbar toolbar = findViewById(R.id.my_awesome_toolbar);
//Get rid of the title drawn by the toolbar automatically
toolbar.setTitle("");
TextView toolbarTitle = (TextView) toolbar.findViewById(R.id.toolbar_title);
toolbarTitle.setTextColor(Color.BLUE);

Taken from Getting ActionBar Title TextView with AppCompat v7 r21

how to get the action bar button? findviewbyid seems doesn't work

1.Create a variable MenuItem in your Activity class

    MenuItem menuItem;

2. Find your variable in onCreateOptionsMenu

    @Override
        public boolean onCreateOptionsMenu(Menu menu) {
            getMenuInflater().inflate(R.menu.menu_main, menu);
            menuItem = menu.findItem(R.id.item_circuit);
            return super.onCreateOptionsMenu(menu);
        }

Disable the item in your buttonClick method

 button2.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    menuItem.setEnabled(false);
                }
            });