Recently I came across the use-case of using tools:context in my layout files for activities.
I learned that I can use it to associate an Activity class file to my layout file.
But how can I use it to associate a Fragment class file to any layout?
Bacuase as I have tried, it is only showing Activity list in autocomplete suggestion.
There is a bug in Android Studio, you have to write it manually, it will appear red(indicating it's unresolved) until you finish typing, then it will appear in green
Have you tried it doing like this:
Let's say Relative layout is your parent layout in your fragment's layout:
<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"
tools:context=".Folder.Fragment" >
Now this .xml file will be associated with your .Fragment class which is a fragment.
Key point: Autocomplete is not showing name, manually enter it and it will compile.
Create a fragment with a layout file and see the layout file for tools:context.
I just had the same problem and typing in the fragment name didn't get the fragment name recognized in the tools:context=".NameFragment" statement.
What did work was first deleting both the class and xml files for that fragment and then:
Right click on the package name and choose New->Fragment->Fragment (Blank)
Enter in your fragment name (the layout name is automatically created on the same form) and click Finish.
This method created both the class and xml files at the same time. and at this point, the tools:context statement in my xml file had my fragment name automatically and was not red but green text (indicating that it was recognized). I'm seeing this on Android Studio Bumblebee 2021.1.1.
Earlier I had created the xml file first and then created the class file (and had problems with the fragment class file name not being recognized by the tools:context statement).
Related
This question is quite basic. Let me go with an example.
I have two activities
activity_a.xml
ActivityA.java
activity_b.xml
ActivityB.java
Both the XML files contain only a TextView to display a simple text. As usual, the TextViews are going to be referenced in the corresponding .java files using their View id
My question is, if it is right to reference the TextView in both the XML files with same id? (like using the below code with exactly same id for activity_a.xml and activity_b.xml)
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="#+id/textview"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
I was practising this procedure without any problems. When trying to reach the corresponding xml code for the TextView using Ctrl + Click (on Windows), I am provided with two options (to display the TextView's xml code from activity_a.xml or from activity_b.xml).
Also, what is the recommended way to name a View in Android? This will be helpful, when your Android project contains multiple layout files.
Yes , if you have same name of view or view group in different layout then it tells from which layout file it belongs to, ask for select required layout file.
so for that you have to follow proper naming conventions to avoid this type of confusion
https://github.com/ribot/android-guidelines/blob/master/project_and_code_guidelines.md
or you can give name like
activity_home_tvUserName if username textview from home activity
and
activity_profile_tvUserName if username textview from profile activity.
if it is right to reference the TextView in both the XML files with same id?
It is totally fine, the compiler will only look at the ID under a single view hierarchy.
e.g.: findViewById(R.id.textview) inside ActivityA.java will only search for textview ID inside activity_a.xml (assuming you have setContentView(R.layout.activity_a); beforehand.
what is the recommended way to name a View in Android?
In my opinion, you just need to be consistent in naming your view throughout the app. The main goal is to avoid misinterpretation and confusion.
Hope it helps!
They are in different activities, so you should have no problem using the same id. you could event declare them both as #+id/textview. However, why not just use the same XML file for both activities? No reason you can't.
You can also create an ids.xml file under the values folder and declare all your ids under it, so you don't have to declare them in your layouts, but this is not a very common approach.
if it is right to reference the TextView in both the XML files with same id?
My answer is Yes, It is right.
Whenever we set the setContentView(R.layout.activity_a), then it'll search for the given id within the above activity. Local attribute having the same id will take the more preference over the other attributes with the same id.
But having unique id's is Best practice.
I'm pretty new at this. The problem accurs right after I've created a project with a blank activity. On the screen appears a "Hello World!" TextView but this TextView isn't displayed in the XML File and I can't select it in the Designtab but in order to delete it I either need to select it in the Designtab or delete the code in the XML File. How can I do this?
http://i.stack.imgur.com/g7Moi.png
This is a picture of the Preview Page in Android Studio with the XML Code to the left.
Thanks for your help!
If you open the content_main.xml layout file, you should see the "Hello World" TextView. You are currently using the include tag to load a seperate xml file
This is the standard auto-generated code by Android Studio. In the activity_main.xml you have the code for the Toolbar and the FloatingActionButton and it is included another xml file content_main.xml where you put all the elements you want.
I have just begun learning Android App development. I have Android Studio 1.4. In my layout folder I have two XML files (content_main.xml and activity_main.xml). I use online tutorials to learn but they have only activity_main.xml in them. So what i want to know is what are the functions that should be used in these respective files. can i just use activity_main.xml and just let the other be ? and vice versa.
The modern Android approach is based on Fragments, which are, in a way, "small Activities", which you can put in Activities, gaining lots of flexibility.
Therefore, activity_main.xml is simply the Activity layout containing a container (FrameLayout most probably) and content_main.xml is the layout for a Fragment put into this container somewhere within MainActivity.java. You should study the code in there to understand it better :)
As I know, there must be include statement in your activity_main.xml file as follows :
<include layout="#layout/content_main" />
that means it is calling the content_main.xml which has actual elements to be hold.
There will be no problem if you cut and paste all the content of content_main.xml file and paste it in activity_main.xml file in place of include statement(tag).
You can delete your content_main.xml after doing as above.
In your activity setContentView() statement should be look like as below :
setContentView(R.layout.activity_main);
According to new design pattern in android studio activity_main.xml will determine how the look of the main activity should be. And on the other hand content_main.xml will determine the contents in the activity_main.xml. That is content_main.xml will contain the textview, edittext, button etc component. And the content_main.xml will be included by the activity_main.xml .
So we can think of content_main.xml just like partial in HTML.
activity_main.xml will contain your activity global design, and
content_main.xml the contents.
What is the role of content_main.xml in android studio 1.4?
So it seems the content_main.xml is a part of a new design pattern introduced in Android Studio 1.4.
For the moment, to get along with the tutorials you can find pick the 'empty activity' when creating a new project. It will not contain the content_main.xml.
As mentioned before, the layout file used for your activity is set with setContentView(R.layout.activity_main); in the onCreate function of the activity.
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
I have not seen Android Studio creating two layout files for one activity. Perhaps the content_main.xml was generated for a previous activity, wasn't it?
Anyway, it doesn't matter what is the name the layout file. Choose one and go for it. Just remember to set the right one in your Activity:
#Override
protected void onCreate(Bundle savedInstanceState){
setContentView(R.layout.your_layout_here);
}
use that one which is set in Activity class. i mean set to setContentView(). or please provide your code if you want more description.
I updated my android studio to latest version that is android studio1.4.
By default in a new project, there is a file content_main.xml in layout folder.
What is the use of this file?
According to new design pattern in android studio activity_main.xml will determine how the global UI of the Activity should be. And on the other hand content_main.xml will determine the contents in the activity_main.xml.
That is content_main.xml will contain the textview, edittext, button etc component. And it will be included by the activity_main.xml.
So we can think of content_main.xml just like partial in HTML. activity_main.xml will contain your activity global design, and content_main.xml will contain the contents.
From view of what they contain:
activity_main : Co-ordinator layout, ViewPager etc
content_main : Developer choosen elements. textview, edittext, button etc.
What the android developer website says about them is
activity_main:
This XML layout file is for the activity you added when you created
the project with Android Studio. Following the New Project workflow,
Android Studio presents this file with both a text view and a preview
of the screen UI. The file contains some default interface elements
from the material design library, including the app bar and a floating
action button. It also includes a separate layout file with the main
content
content_main:
This XML layout file resides in activity_my.xml (activity_main) ,
and contains some settings and Textview(other) element.
The difference between content_main.xml and activity_main.xml (for the class MainActivity) exists since the API 23. The difference between them is the following:
The content_main.xml is used for displaying the things that the
user should see. So it contains the elements which are for the user.
As you can see in the name, the content_main.xml determines the
contents you can find in your Activity (MainActivity in this
case). You use this xml-file to add new contents (Views) to your
Activity.
The activity_main.xml has some special tasks. It contains for
example: The floatingActionButton (the small round button you use in
gmail for example) The tabLayout The coordinatorLayout So the
activity_main.xml determines how the Activity (MainActivity in this
case) should look. It determines its design.The content_main.xml is
a part of the activity_main.xml.
I copied a .java class and .xml layout. I thought I renamed everything in order to create a new class, but the new class is loading the old layout when I start a new Intent. Am I missing someplace where I need to enter the name of the new layout file I have created from a copy of another class' layout?
I think I missed this line:
setContentView(R.layout.xxx)
This should do it!
If you have not set the launcher activity in manifest then you have to specify which Activity starts first
If you have set old XMl in setContentView(R.layout.xxx) then this loads old layout so check for proper xml.
After trying the other answers, try checking the following attribute on your layout element:
tools:context=".SignUpActivity">
That was it for me.