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layout element defined globally

I'm trying to add a "You are offline" element to the bottom of each layout in my Android app. I would like to define it globally, not to paste the same element to each xml layout file.
I could probably create some ParentActivity and append it programmatically, but is it a good solution?
What is the best way?
Thanks.

Use custom BottomSheetDialog. You do not have to inclue it in layout file. Instead, you will call it programmatically.
BottomMessageDialog:
public class BottomMessageDialog extends BottomSheetDialog {
public BottomMessageDialog(#NonNull Context context) {
super(context);
setContentView(R.layout.dialog_bottom_message);
}
}
dialog_bottom_message.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="center">
<TextView
android:layout_width="wrap_content"
android:layout_height="50dp"
android:text="You are offline"
android:textSize="18sp"
android:gravity="center"/>
</LinearLayout>
Call it:
BottomMessageDialog bottomMessageDialog = new BottomMessageDialog(MainActivity.this);
bottomMessageDialog.show();
Hope it will help.

best way is creating a custom xml file with any name you want and you can use it any number of times you want without any copy and paste.
step 1: creating custom layout named footer_message .
<TextView
android:layout_width="match_content"
android:layout_height="wrap_content"
android:text="You are Offline"/>
step 2: adding that custom layout in another xml which you want that msg.
<include
android:id="#+id/footer_message"
layout="#layout/footer_message"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>

create an xml file
footer.xml
make your layout in it and write this code in the xml files where you want that footer
<include
android:layout_height="wrap_content"
android:layout_width="fill_parent"
layout="#layout/footer"
android:id="#+id/footer"/>

Android Studio cannot find symbol variable

I installed Android Studio about two days ago, I also installed the most updated version of Java and JDK 1.8 (I think it was Java SE 8u101). I am able to edit code and I'm following a tutorial from the official Android Studio website. (Here: https://developer.android.com/training/basics/firstapp/building-ui.html)
However, upon hitting run I've gotten the two following errors:
Error:(24, 57) error: cannot find symbol variable activity_display_message
Code for this:
ViewGroup layout = (ViewGroup) findViewById(R.id.activity_display_message);
Error:(33, 25) error: cannot find symbol variable EXTRA_MESSAGE
Code for this:
intent.putExtra(EXTRA_MESSAGE, message);
What might I be doing wrong? The emulator pops up and I can get to other apps on the phone but I just can't get my app to load. Should I have installed Java SE 8u102 instead?
I also got a second error message:
Error:Execution failed for task ':app:compileDebugJavaWithJavac'. > Compilation failed; see the compiler error output for details.
Any help is appreciated.
Below is my code for the first xml file, "activity_main.xml":
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<EditText android:id="#+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="#string/edit_message" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send"
android:onClick="sendMessage" />
</LinearLayout>
Below is my code for "activity_display_message.xml"
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.appno1.DisplayMessageActivity">
</RelativeLayout>

Add this to your MainActivity:
public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
You might have missed this line, which can be found in the "Build an Intent" part.
Refer this for more, from the original page.

I think you might lose the last note in the tutorial.
so you just add android:id attribute to the activity_display_message.xml file and it will be ok!oh actually you should add into the layout element which is the valid location.

My advice is, try to clean the project and build it again. If you want to access newly added resources you need to build the project. Cleaning will help to remove all previously autogenerated resources from project and building will help to create them again + new ones.

You should add EXTRA_MESSAGE as static final, like:
private static final String EXTRA_MESSAGE = "message";

Regarding this error,
ViewGroup layout = (ViewGroup) findViewById(R.id.activity_display_message);
check that the file res > layout > activity_display_message.xml as the id specified as android:id="#+id/activity_display_message"

Attempting to Implement a Thread for a Game Loop

I am a novice learning Android development and the next step I must take is to be capable to understanding threads to be able to implement a game loop.
I have taken knowledge from google and StackOverflow and snippets from examples to come up with a lump of code that seems to not be working:
MainActivity.java
GameSetup.java
GameView.java
activity_main.xml
game_setup.xml
MainActivity.java is a simply title screen with a play button. This seems to work fine and will link to the next activity. However, I am getting a crash whenever I attempt to load up the next activity. My guestimations based on the error lead me to believe that threads have issues with RelativeActivity, but I'm not so sure on what the issue may be exactly, I am rather confused.
Here is the error I am getting thrown, I am having issues trying to decipher the issue with it.
Thanks.

R.id.layout is a RelativeLayout but you are trying to cast it to GameView, that's causing your crash.
Edit:
To add your GameView to the RelativeLayout you can do
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/layout"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<com.your.package.GameView
android:id="#+id/my_game_view"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
<ImageView
android:id="#+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/ship1" />
<ImageView
android:id="#+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/ship1" />
</RelativeLayout>
and retrive it with
GameView myGameView = (GameView) findViewById(R.id.my_game_view);

Hmm, from the code you have written so far, I can explain the reason for the ClassCastException.
You are declaring a RelativeLayout in both XML files.
Both RelativeLayouts use the same android:id "#+id/layout"
In GameView.java you try to find a view by specifying the id
m_game = (GameView) findViewById(R.id.layout);
IMO you are retrieving one of the RelativeLayouts and then try to cast it to a GameView. As this is not possible, Java throws the exception.

findViewById Error cant find id in XML

I cant find out why my findViewById is not linking to the XML file and it is driving me nuts. The is is in the XML file but it is still not Finding it in the java MainActivity file.
here is my XML
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<EditText
android:id="#+id/editCentimeters"
android:layout_width="wrap_content"
android:layout_height="27sp"
android:layout_alignLeft="#+id/editInches"
android:layout_alignTop="#+id/textCentimeters"
android:ems="5" >
<Button
android:id="#+id/buttonConvert"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/editInches"
android:layout_centerHorizontal="true"
android:layout_marginTop="98dp"
android:text="#string/convert" />
And here is my Java
EditText etCentimeters = (EditText) findViewById(R.id.editCentimeters);
Button buttonConvert = (Button) findViewById(R.id.buttonConvert);

I was facing the same issue. Just comment out the line which is throwing the error & BUILD the project once. Intellisense (ctrl + space) then will show you the IDs.

You need to take care of 2 things here:-
EditText etCentimeters = (EditText) findViewById(R.id.editCentimeters);
Button buttonConvert = (Button) findViewById(R.id.buttonConvert);
Firstly, the above code should be present in the onCreate() method.
And next, you need to place that code snippet below this line in the onCreate() method, not before it.(I'm assuming that the setContentView is already present, if not, add that)
setContentView(R.layout.main);

use setContentView(R.layout.main); at the onCreate of your Activity

You can refresh project.
And also check ur setContentView(R.layout.YOURLAYOUT_NAME) in Your activity.
Make sure that u are using ur code in activity.

Just clean & build in order to find the ID.

Clean & build didn't work for me. I had to restart Android Studio.

TextView Not Accessible

I am new to Android.I am making a random generator program which on button click generates a number and display it on textview. I am unable to access textview when i type R.id. i don't get the name of the textview but i get the name of the other components. My layout code is:-
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">
<EditText android:id="#+id/edit_message"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="#string/edit_message" />
<TextView android:id="#+id/txt02" android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send"
android:onClick="sendMessage" />
</LinearLayout>
Java code is:-
public void sendMessage(View view) {
// Do something in response to button
EditText editmessage = (EditText)findViewById(R.id.edit_message);
String message = editmessage.getText().toString();
Random r=new Random();
int i1=(r.nextInt(80) +65);
message += "\n " + i1;
// Create the text view
TextView textView = (TextView) findViewById(R.id.); // not able to access R.id.txt02
}

The problem most likely is that your R.java file hasn't been updated with the EditText you have added. In eclipse, you can force an update to do this. Try Project->Clean as mentioned by Michal Z. in the comments.
You can also set the option to build automatically in eclipse by checking the Project->Build Automatically option. This will ensure that eclipse will automatically build your project and update your R.java file every time you save your project.

If cleaning your project doesn't help, I'd check your source files to make sure there isn't a line saying "import android.R" in your imports because that will import the standard Android R object (which doesn't include any of your declared resources). Eclipse does this sometimes when you cut and paste code and it can be frustrating, but deleting the import and cleaning / building your project should fix it.