How to reference a string in strings.xml of an Android library in code?

Question

To reference string foo in strings.xml (in res\values) of an app project, one can simply use

getString(R.string.foo)

getString is a method of Context.

Suppose an Android library has a string foo in its strings.xml. How can it be used in a method of the library?

Edited: It has been suggested to pass a reference of Context to the library method so getString() can be used. Since it is a context of an app's project, there is potential conflict that can be illustrated as following:

Suppose: The library has a string foo with value = "library foo". An app project has a string foo with value = "app foo"

The following code

Log.d("Debug", "App foo ID: " + R.string.foo);  
Log.d("Debug", "App: foo value: " + getString(R.string.foo));

generates:

03-22 05:53:55.590: D/Debug(16719): App foo ID: 2131230723
03-22 05:53:55.590: D/Debug(16719): App foo value: app foo

In a library method, the following code

Log.d("Debug", "Library foo ID: " + R.string.foo); 
Log.d("Debug", "Library foo value: " + context.getString(com.my.library.R.string.foo));

generates:

03-22 05:55:03.680: D/Debug(16719): Library foo ID: 2131230723
03-22 05:55:03.680: D/Debug(16719): Library foo value: app foo

The above shows the ID conflict hence erroneous string value.

mpolci · Accepted Answer · 2015-03-13 22:08:29Z

As you indicated to reference a string resource defined in your library you can use getString() method, you only need a Context, but in your example the conflict is generated by the same name of the strings.

When you define a resource in your library you have a conflict if you use the same name of a resource in the application module. To avoid conflicts you have to use unique names, for example using a common prefix for resource names in the library, it is not sufficient the different package name.

To resolve you can use the following names:

mylib_foo in your library
foo in your application

Source from android documentation: http://developer.android.com/tools/projects/index.html#considerations

As you develop your library modules and dependent applications, keep the points listed below in mind:

Resource conflicts

Since the tools merge the resources of a library module with those of a dependent application module, a given resource ID might be defined in both modules. In this case, the tools select the resource from the application, or the library with highest priority, and discard the other resource. As you develop your applications, be aware that common resource IDs are likely to be defined in more than one project and will be merged, with the resource from the application or highest-priority library taking precedence.

Use prefixes to avoid resource conflicts

To avoid resource conflicts for common resource IDs, consider using a prefix or other consistent naming scheme that is unique to the module (or is unique across all project modules).

DDRBoxman · Accepted Answer · 2013-03-23 03:27:38Z

5

A library project should be able to reference it's resources in exactly the same way.

Is there a specific use case / code sample that illustrates this not working?

Any strings defined in the parent project will overwrite the library. Even actionbarsherlock uses a prefix ex. abs__action_bar_home_description

edited Mar 23, 2013 at 3:27

answered Mar 21, 2013 at 21:00

DDRBoxman

3112 silver badges10 bronze badges

6 Comments

Hong Over a year ago

The method does not have a Context reference, how can getString() be used?

DDRBoxman Over a year ago

The only way is with a context. Usually I just set up my method to accept a context from the calling application.

nicopico Over a year ago

you must pass a Context parameter to your method. Note that View has a getContext() method, if you already have a parameter of this type

Hong Over a year ago

I was thinking about passing a Context, but the library can be used by unlimited number of apps. I am very unclear how the resources of the library are incorporated into each app without causing any potential string ID conflicts. When I use getString(R.string.foo) now in an app, I know it goes to the app's strings.xml to fetch it. How does an activity's context know to go to the library's resources to get a string. I must be missing something fundamental here.

DDRBoxman Over a year ago

When you import the R package you specify the parent domain. So in your library you import com.example.test.libraryname.R; While your app might use import com.example.test.app.R;

|

Anand M Joseph · Accepted Answer · 2020-06-24 04:57:58Z

2

//For boolean values
    int resId = context.getResources().getIdentifier("bool_ID", "bool", context.getPackageName());
    if(resId != 0){
       System.out.println(context.getResources().getBoolean(resId));
    }

    //For String values
    int resStringId = context.getResources().getIdentifier("string_ID", "string", context.getPackageName());
    if(resStringId != 0){
        System.out.println(context.getResources().getString(resStringId));
    }

answered Jun 24, 2020 at 4:57

Anand M Joseph

8958 silver badges7 bronze badges

Collectives™ on Stack Overflow

How to reference a string in strings.xml of an Android library in code?

3 Answers 3

Comments

6 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

6 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related