Android get layout by id

Android — how to get the layout id from a view?

Hello fellow developers!

i’ll keep this as simple and short as I can, I have a fragment, and in my onCreateView I am sometimes giving it different layouts depend on my status.

is there any way of knowing on which layout I am?

basically, my «findViews» method gets that View, and I was wondering if there’s a way to know which layout i am on with a switch statement for example or something like that.. like this :

I am trying to do something like that with no success.. all i get is errors and such, is there a way to do that?

thanks a lot in advance

4 Answers 4

is there any way of knowing on which layout I am?

Sure. Check programState . You are already doing that to determine which layout to load, so use that to determine which layout you loaded.

I was wondering if there’s a way to know which layout i am

Use if (programState) , the same way you did in onCreateView() .

Beyond that, a widget has no idea what layout resource it came from. So, somewhere, you need to track that information yourself, and you seem to be doing so already in programState .

try mainView.getId() in switch. I think that’s what you need

Change your method to something like this:

If you have various Views and you need to differentiate them — try adding tags to them.

1 — If you are going to have more then one tag type — create keys for them. And use mainView.setTag(TAG_TYPE_ID_1, 10011) (many tags for a view) rather than mainView.setTag(10011) (only one tag for a view). In this case TAG_TYPE_ID_1 may be your constant field. It must be initialized with id of some Resource. For example public static final int TAG_TYPE_ID_1 = R.layout.my_frame_layout; Also consider placing int viewId = (int) mainView.getTag() into try/catch because you can get ClassCastException if you will put there a String for example but will try to get int .

But for this example we assume you don’t need lots of tags and you know that you have only int as a tag.

2 — Set tag into the view in onCreateview() method in your fragment:

3 — Then read the tag value in your view and decide what to do

NOTE: don’t forget that here switch((int) mainView.getTag()) you can get ClassCastException or NullPointerException if tag will be different type or null

Also int codes like 1011 , 1012 etc. is better to store as a constant fields

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Get View by ID from attributes in Custom View Class

I want to get a view from his ID, from the attribute in the xml. I have tried with getParent() but it’s return null.

XML

The attribute revealView is referencing the View above.

Code — NetworkLoading (init())

1 Answer 1

It seems that you’re trying to find your revealView too early. In the constructor, the View will not have yet been added to the layout it’s in, so getParent() will return null . Keep the resource ID for the revealView as a field, get its value in the constructor, and then find the View in the onAttachedToWindow() method.

In the code you’ve posted, remove the last line — the last finishView = . line — and instead save the resource ID to your field.

Then find the View in the onAttachedToWindow() method instead.

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How to get the name of layout associated with an activity?

In onCreate() method, we can can use setContentView(R.layout.something) to associate a layout to an activity. Is there anyway I could retrieve something later for an activity?

I know I can use this.findViewById(android.R.id.content).getRootView() to get activity’s content view but not sure if there anyway from there I can get something ?

5 Answers 5

When you want to solve it generally for all your activities:

Or you can do it simply so:

You can get the root view of your Activity using:

If you need to get view that you added to your activity using setContentView() you can use

But you can also use the same id used in the root element of your xml.

use this code to get layout id:

and this to get String:

Since Activity extends from View, you shouldn’t need to do this. You are, in a way, already referencing the root view inside the activity. That is what allows you to call findViewById() any time. If you wanted to find the root element, make sure your root (LinearLayout or RelativeLayout) has an id, and you could do something like:

You can use setConetentView(R.layout.content) in any method in any activity, as long as content.xml exists as a layout file in the layout directory.

An activity is a single, focused thing that the user can do. Almost all activities interact with the user, so the Activity class takes care of creating a window for you in which you can place your UI with setContentView(View). While activities are often presented to the user as full-screen windows, they can also be used in other ways: as floating windows (via a theme with windowIsFloating set) or embedded inside of another activity (using ActivityGroup). There are two methods almost all subclasses of Activity will implement:

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Android add ID to a layout

How do I define an ID to a layout?

I am trying to add an ID to a linearlayout and setting an onclick listener:

6 Answers 6

Since you have this

You can do as below

If you have button then you can do as below.

Then in your activity

and set your id from the xml

The easiest way would be to just add it in your layout xml:

It can then be referenced from your code via your.package.R.id.myId .

In onCreate() of your Activity:

And have your Activity implement View.OnClickListener.

This could work..

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Can I use the same id in different layout in Android?

I am new to Android development. Is it fine to use the same ID for images and TextViews in different Layout XML files?

When eclipse auto-list them for me, it lists all the layout variables from the project, so will it collide? Till now I have not noticed any problems using the same ID in different layouts, but I am concerned in long run.

4 Answers 4

Short answer: Yes, you can.

Long answer: You can do this because whenever you use findViewById() to get a reference to a part of your layout, the method only looks for that view in the currently inflated layout. So even if you have another view with the same ID in another layout, Android will not look for it there.

It is recommended that you use different ids for different layouts. On the long run, when you will have a lot of layouts and therefor a lot of ids it will get very complicated to differentiate them.

I usually name my ids like this: layoutName_elementId .

It works for me to easily find the id I’m looking for, especially when using autocomplete (I know on what layout I’m working, but I don’t really know the id; in this case, with my naming strategy, I only type the layout name and it brings on all the ids of that layout).

More information on layouts and ids can be found here.

According to developer API guides:

An ID need not be unique throughout the entire tree, but it should be unique within the part of the tree you are searching (which may often be the entire tree, so it’s best to be completely unique when possible).

So the short answer is that it’s not mandatory but it’s a good practice to avoid possible conflicts.

Not recommended, because if in future you will need to refactor the view id , Android studio will refactor it in all XML files and classes and you will get into trouble.

But there are also some cases when you do need to use same id for example if you have some abstract and you reuse multiple layouts.

In case you have multiple views with same id’s in your project and you need to refactor, do it manually, don’t use build in IDE function, change the id in the target view inside XML layout then fix the red error inside layout.

Update:

Currently Android studio support refactoring with «refactor in current file only» option.

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