Develop Reference

How to share common code among multiple activities? Please, this is not a repeated question

Actually I'm trying to create an app it has Navigation Drawer and Google Sign In for which I also need to add auth code every where.
I wanted to know is there any way of putting all the navigation drawer code somewhere else (say in different class file) and then calling the code in the different activities?
As copy pasting the same thing again and again is sometime irritating.
Please help.
Thanks.

You can do it very simply.
But this is not a good approach that you sign in with google in every item of navigation drawer. If you sign in user on first screen and then access that user wherever you want without doing unwanted things in code.
But Still you want solution
Solution
you should make a google sign in method in a class with parameter Context. Access it wherever you want from that class provides sign in method.
Library
you can do it very simply by library from github:
Google Sign in library

The process is simple, create classes and pass the data as a parameter

How to verify that IntentionAction was called on an interface file? IntelliJ Platform SDK

I am new in the IntelliJ Platform SDK and a plugin development.
I want to implement IntentionAction that available only if press Alt+Enter in an editor when a cursor set on an interface declaration.
In other words, expected behavior as in cases when the "Implement interface" intention action appears.
Place in an editor:
public interface SomeInterfaceNameDeclaration {

In your IntentionAction.isAvailable() method, you receive an Editor and a PsiFile. You can use file.findElementAt(editor.getCaretModel().getOffset()) to find a PSI element at caret, and then PsiTreeUtil.getParentOfType() to find an element of the type you need. See the documentation for more information.
Also, you can refer to the source code of the "Implement interface" action as an example.

See the code sample conditional_operator_intention for an example of using the Psi Tree in ConditionalOperatorConvertor.isAvailable() to determine whether to enable or disable the intention action functionality.

How can I generate and compile Java files in Android at Runtime

I know with javax.tools.* it is possible, but since this is not included in the Android API, I'm desperately wondering, is this possible?
Right now, my goal is to create a drag-and-drop tool to allow users to create their own layouts (as not everyone wants to learn Mobile Development, as it requires a lot of time, dedication and practice) similar to how Android Studio does it's own. However, of course the most important thing is to implement functionality via onClickListener and onTouchListeners. I've begun remedying this by creating my own DSL (Domain-Specific-Language) with a GUI front-end allowing users to choose what they want via PopupMenu and SubMenus. For example...
Statements
{ if, for, while }
Statements must be followed immediately by a reference and then a conditional (obtained from that reference), like a "if(Object.conditional())" statement.
References
{ Object1, Object2, Object3 }
The objects are references to other Views (I.E, Buttons, Layouts, WebView, etc.).
Conditionals|Actions|Getters|Setters
{ isSomething(), doSomething(), getSomething(), setSomething() }
Each Reference's methods, wrapped so that each wrapper keeps track of it's method's attributes and description (hence documentation).
It would go something like such...
IF ImageView1.isVisible()
ImageView1.setVisible(false)
ELSE
ImageView1.setVisible(true)
Of course, the method setVisible(boolean) is a wrapped version of setVisiblity(int).None of this is typed, it is obtained from a simple PopupMenu which shows them the applicable selections based on current context.
How I plan on transcribing this to compiling code was to convert the statement into Java code, inserting references on the fly as they are needed (I.E, ImageView1 would be defined in java as private ImageView ImageView1;), generate methods somewhat similar to how ButterKnife generates it's extra classes for it's onClick and onTouch annotations, etc.
Then, after planning all of this (been working on it for 2 weeks now), I find out that Android does not have support for compiling code like this. Please tell me something like this is possible. It's something I 100% wanted to do. Is this possible with any third party libraries?
If not, is there some possible way to mimic doing so? I could do it the long and slow way, of preparing every such possible way, keeping track of the references myself through a map, and when it is about to be called, directly call the implemented method for the View associated with that key, which theoretically COULD work. In fact, that'd be my second go-to if I can't. It'd be messy though.
Sorry if this is too long, I just want to get this to work.
TL;DR: Is there a way to compile a generated Java file created at Runtime in Android (since javax.tools.* does not exist), and if not what would be the best way to do so?

SWT CTabItem meaning of setData and setControl

I started with SWT programming and I am trying to reprogram this example, where CTabItem's are created within a CTabFolder. But since I am a very noob in GUI programming, some things are very unclear to me.
What is the purpose of setData() and setControl() for a CTabItem? In which cases or for which situations I use these methods? I have read the API documentation for setData, which says:
Sets the application defined widget data associated with the receiver to be the argument. The widget data is a single, unnamed field that is stored with every widget.
But I don't understand this and also the documentation for setControl. Can anyone please explain me the purpose of these methods?

The setData(Object) and setData(String, Object) methods are used to add additional data to a Widget. This data can later be accessed. Examples for this use are if you want to identify the widget later on or if you need this additional information someplace else.
The setControl(Control) method assigns the content to the item. This means if you call item.setControl(myContent), this myContent will be shown if item is selected by the user.
Example answers that suggest using setData():
Swt combobox name/key pair
How to attach data to TreeItem in SWT/Java?
HTML "getElementByID" implementation for SWT widget

is there an equivalent to a "Focus Listener" in Objective-C or iPhone SDK? (Coming from Java)

I am a student programmer who has taken up Objective-C on my free time as my college doesn't teach it. We have only used Java and basic C so far. I am in the middle of making a program for the iPod and was wondering if there was any type of way to call a method in a class similar to the way a Focus Listener does in Java? I have a view that I would like to call a refresh method (to update the newly inputted titles of buttons from another view) when the view is put at the top and visible again. Is this too easy or is there a more methodical way of doing that? I have tried to just call the method from the other view class but it does not seem to work (says the other class is either undefined or may not accept the method call and crashes on execution).
Any insight would be appreciated. Thank you for your time.

I don't know if I have understood the issue very well but when a view is being visible the "viewDidAppear:" method is call in the UIViewController.
Otherwise the equivalent of the Listener pattern in Objective-C is the NSNotification. You can add an Observer like that:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(aMethod) name:#"aNotification" object:nil];
And the Observed handled his message like that:
[[NSNotificationCenter defaultCenter] postNotification:[NSNotification notificationWithName:#"aNotification" object:nil]];