Develop Reference

Android-Studio: How to make a resource string value the same as its name

I want to use the string resources to save some key values. So, I have something like this:
<string name="key_name">key_name</string>
The resource name and the resource value are the same. There is no need for me to make a difference between them, as it is just to cleanly store one value.
To reduce redundant information,
is there a way to just tell android-studio that the name equals the value? Something like this?
<string name="key_name"/>

I think you can't do it. It looks like you create a variable, you must name it and when you need you can set its value.
You can't create a variable with same values with name at the same time.

I think you have the wrong resource type. A string resource is used for mapping a name to a text. From what you're describing here you only need the name (and then can extrapolate the text from it).
Using strings with matching name and value shouldn't be necessary:
If you're going to be referencing them from Java or Kotlin code, you still need to know the name (i.e. R.string.key_name), so you might as well just use the string value there.
If it's for using inside XML code (where you want to pass the value of a string, e.g. text="#string/key_name") most of the time you can just use the raw string there (i.e. text="key_name").

Android Too many ID

I'm building an Android app and I begin to have too many Id resources.
I wondered if there would be a way to have for example
TextView text = (TextView) findViewById(R.id.activity_name.item)
Thank you

This is not possible to my knowledge as the R class is generated and should not be edited.
But I think you can do the next best thing and make your naming convention match that format with underscores.
for example for all of your id's on the main page, this could be the text on a list element. MainPage_List_Text
Here is another so page you might find useful. Are there conventions on how to name resources?

no resource found that matches the given name at hint = #string/edit_message

I am new to android, I am trying to create a sample UI which is described in the developer.android website. When I add a edit text, I am getting that error message.

If you are currently using this: android:hint = "#string/edit_message", just do like that: android:hint = "edit_message". This is called hardcoded string. Its working, but its not recommended that you make strings this way. The other way is to go to resources, then to strings folder, and there should be one .xml, with strings. To make a new string, just copy the last one, change the name, and the content between >...<, where your string should be. To use that string you get it by its name. So if you name it "myStr", to use it in editText, you need to say: android:hint="#string/myStr" and you will get the content of the string. Hope this helps. Mark as answer if it does. Good luck.

Did you add the string resource?? To the left is package explorer. Select Your project and go to its res folder. In res folder select values and then click on strings.xml. Add your string resource there and save it. Then I dont think theres scope for such error messages.

Get resources by int number

I sometimes see this declarations in Android source code:
mContext.getString(2131361954);
Notification n = new Notification(2130837696, "123", System.currentTimeMillis());
// Example code - does not match together
I think the numbers are some resources from the project, right? Why sometimes people work with this numbers instead of using the R class? Is it faster or something else?
And how can I check which resource is assigned to that numbers? Is it possible to get number which is used if I only have the file or is this number random? Maybe with the file name or the MD5 hash of the file or something else?

There is no performance difference, as all members of the R class are static and final, and are directly swapped in during compile time. This is equivalent to any code that uses R.x.y, so the performance is the same.
I would strongly recommend against using the numbers directly in your project as they may change during the addition, removal and modification of resources.
You can check the resource to which that number corresponds by converting it to hex, opening up the R.java file and searching for that hex number and seeing what it is assigned to.
You can also use getResources().getResourceEntryName(int resid); and pass it the ID at runtime to retrieve the file name.

Android R.java use

When we add some entries in the strings.xml file or layout.xml file, then the R.java file gets modified automatically. Again, if we want to refer something from the layout file such as reading the EditText value entered by the user, then again we refer the R.java file at our java code to read the values.
What is this R.java file all about? The values of each entry of this R.java file seems to be in HEXADECIMAL format but what is its use?
I have read the doc but i get fairly confused for this R.java :(
Please someone step forward and explain what is this R.java file all about :(
Regards,

http://developer.android.com/guide/topics/ui/declaring-layout.html says:
android:id="#+id/my_button"
The at-symbol (#) at the beginning of the string indicates that the
XML parser should parse and expand the rest of the ID string and
identify it as an ID resource. The plus-symbol (+) means that this is
a new resource name that must be created and added to our resources
(in the R.java file).
The R.java file is generated by the Android Resource Manager (aapt.exe) and contains references to all resources of your app. Each reference is a unique id (public static final int). These constants are written to the R.java file in hexadecimal format. The logic of assigning specific integer to each resource is private to the Android Resource Manager. You can look at the source code of aapt.exe on the internet, e.g. at http://gitorious.org/rowboat/frameworks-base/trees/d58fb97ddf052b3ceac921ac7e936af990392b2c/tools/aapt

It turns resource objects into Java recognizable names for you to refer to in your code.

The R class is basically the way Android provide resource access from within your code. As you wrote when you alters strings.xml etc on save of that resource file Android SDK will recompile the R class to make your changes accessible for within your code. What the values in R class are is more or less not important since its used by Android internally to map, for example a string to an ID.
To reference a string from within your code you use R like this:
R.string.MyString
If you string in string.xml is called MyString. Same for layouts etc.
I guess this is what you read, but otherwise it's pretty good explained here.