Develop Reference

How do I use databinding to combine a string from resources with a dynamic variable in XML?

I have a TextView which has a hardcoded string and I have a dynamic variable that I want to put at the end of this string. This is my code:
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:layout_marginLeft="16dp"
android:layout_marginRight="16dp">
<TextView
android:id="#+id/PeopleName"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="#string/Generic_Text"+"#{ Profile.name }" />
</LinearLayout>
I am having an issue with android:text="#string/Generic_Text"+"#{ Profile.name }" . The Generic_Text states " My Name is " then the Profile.name is dynamic and obviously changes from profile to profile. I want it so that the whole TextView output is My Name is {Profile.name}. Any help would be great.

You can do this even simplier:
android:text= "#{#string/generic_text(profile.name)}"
you string should be like this:
<string name="generic_text">My Name is %s</string>
Edit:
Of course you can use as many variables as you need:
android:text= "#{#string/generic_text(profile.firstName, profile.secondName)}"
<string name="generic_text">My Name is %1$s %2$s</string>
It works just because it's designed in data binding. More in docs: https://developer.android.com/topic/libraries/data-binding/expressions#resources

You can do this:
android:text= "#{String.format(#string/Generic_Text, Profile.name)}"
if you use string formatting for your Generic_Text string. ex. %s at the end

Many ways to concat strings
1. Using string resource (Recommended because Localization)
android:text= "#{#string/generic_name(user.name)}"
Just make string resource like this.
<string name="generic_name">Hello %s</string>
2. Hard coded concat
android:text="#{`Hello ` + user.name}"/>
This is useful when you need hardcoded append like + for phone number.
3. Using String's concat method
android:text="#{user.firstName.concat(#string/space).concat(user.lastName)}"
Here space is an html entity which is placed inside strings.xml. Because XML does not accept Html entities or special characters directly. (Link Html Entities)
<string name="space">\u0020</string>
4. Using String.format()
android:text= "#{String.format(#string/Hello, user.name)}"
you have to import String class in layout in this type.
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<import type="String" />
</data>
<TextView
android:text= "#{String.format(#string/Hello, user.name)}"
... >
</TextView>
</layout>
5. concat two strings by string resource.
android:text="#{#string/generic_name(user.firstName,user.lastName)}"
In this case put a string resource in strings.xml
<string name="generic_name">%1$s, %2$s</string>
There can be many other ways, choose one you need.

Use a Binding Adapter.
This sample is written in Kotlin and takes into account that the bound variable can be null:
#BindingAdapter("my_name")
fun TextView.setMyName(name: String?) {
this.text =
if (name.isNullOrEmpty()) "" else "${this.context.getString(R.string.Generic_Text)} $name"
}
then use the binding adapter in your XML instead of the android:text property
app:my_name="#{Profile.name}"

2019 Update, Android studio to 3.4, Android Gradle Plugin to 3.4
No more required to import
<import type="java.lang.String" />"
for string operations. Please check this answer.

strings.xml: <string name="my_string">Hello %s</string>
view.xml: android:text="#{#string/my_string(name)}"

In case if you want to type text in XML, you can use `` quotation.
android:text="#{`Device Name`}"
elsewhere you need to Concat with the String or variable, you can use
android:text="#{`Device Name`.concat(android.os.Build.MANUFACTURER)}"
if you want to Concat string resource instead of the variable you can do,
android:text="#{#string/app_name.concat(`Device Name`)}"

You can also set string resource as parameter to other string resource using formatter like below:
<string name="first_param_text">Hello</string>
<string name="second_param_text">World</string>
<string name="formatted_text">%s lovely %s</string>
and
android:text="#{String.format(#string/formatted_text, #string/first_param_text, #string/second_param_text)}"
"Hello lovely World" will appear on the view.

Just using + operator works for me:
android:text= "#{#string/Generic_Text +' '+ Profile.name)}"
String.xml will be:
<string name="Generic_Text">Hello</string>

In case you can't change the resource string to contain %s at the end (eg. because it's used elsewhere without the suffix):
android:text="#{#string/Generic_Text.concat(Profile.name)}"
If Profile.name can't be null, that's enough. However, if a null happens, it'll crash. You have to add another layer:
android:text="#{#string/Generic_Text.concat(Objects.toString(Profile.name))}"
(which requires <import type="java.util.Objects"/> to work.)
Again: all this extra work is worth it only if you have the resource string used elsewhere. The second reason is when you want to handle null as "empty string" instead of a "null" literal.

just put or append your string resource name it will work fine
e.x #string/test
android:text="#{#string/test+viewModel.name+#string/test}"

yourViewBinding.yourTextView.setText(this.yourViewBinding.getRoot().getResources().getString(R.string.your_string) + yourStringVariable);

Getting a String from Plurals to use in XML?

I am using Plurals to simplify my code. e.g., I used to have
<string name="cat">Cat</string>
<string name="cats">Cats</string>
Using Plurals instead of multiple strings, I now have
<plurals name="cats">
<item quantity="one">Cat</item>
<item quantity="other">Cats</item>
</plurals>
However, I used to retrieve strings to use as titles or summaries in my XML.
e.g.,
android:title="#string/cats"
Having removed that string in favor of a Plural, I am now unsure how to retrieve my string from XML. I did make a naive attempt with
android:title="#plurals/cats"
but this just gives me #1234567890 instead of Cats (or Cat).
Anyone know if it is possible to retrieve a string out of a Plural from XML?

You have to set it by code:
...setText(yourContext.getResources().getQuantityString(R.plurals.cats, catsCountVar));

You can have the run-time benefits of Plurals and the static benefit of string resources by leaving your string resources where they are and referring to them in your plural resources.
From https://developer.android.com/guide/topics/resources/string-resource.html#Plurals (emphasis added).
<item>
A plural or singular string. The value can be a reference to another string resource. Must be a child of a element. Beware that you must escape apostrophes and quotation marks. See Formatting and Styling, below, for information about to properly style and format your strings.
Example:
<string name="cat">Cat</string>
<string name="cats">Cats</string>
<plurals name="cats">
<item quantity="one">#string/cat</item>
<item quantity="other">#string/cats</item>
</plurals>
Now you can use android:title="#string/cats" in XML files and also use
getQuantityString(R.plurals.cats, numberOfCats)
at runtime.

This can now be done in XML, using a data binding expression:
android:text="#{#plurals/cats(catCount)}"
See this page in the docs for more information: https://developer.android.com/topic/libraries/data-binding/expressions#resources

This is now possible from xml. If you have arguments in the plural forms, you have to remember to pass the quantity variable twice. Like in the below example.
<plurals name="number_of_students_in_topic">
<item quantity="zero">None are currently in this topic.</item>
<item quantity="one">One student is currently in this topic.</item>
<item quantity="other">%d students are currently in this topic.</item>
</plurals>
In xml with data binding.
android:text="#{#plurals/number_of_students_in_topic(count, count)}"
This is because, the plurals with arguments are converted in code (In *BindingImpl classes) using getResources().getQuantityString(int id,
int quantity,
Object... formatArgs)
The first count is to select the right plural form, and the second one is to format the String with right values.

If your string includes string formatting with a number then you need to sent the integer variable twice, example
strings.xml
<resources>
<plurals name="numberOfMinute">
<item quantity="one">%d minute</item>
<item quantity="other">%d minutes</item>
</plurals>
</resources>
in java
int min = getNumberOfMinute();
Resources res = getResources();
String formattedStr = res.getQuantityString(
R.plurals.numberOfMinute,
min,
min
); //this will return "20 minutes" or "1 minute" depending on variable
Kotlin File
resources.getQuantityString(
R.plurals.numberOfMinute, //plural from strings.xml file
min, //quantity
min //var arg
)

Here is a way to use a plural resource as an attribute of your custom View.
src/main/res/xml/layout.xml
<com.mypackage.MyView
app:foo="#plurals/cats"/>
src/main/res/values/attrs.xml
<resources>
<declare-styleable name="MyView">
<attr name="foo"/>
</declare-styleable>
</resources>
MyView.java
public class MyView extends View {
private int fooResId;
private int quantity;
public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.MyView);
fooResId = a.getResourceId(R.styleable.MyView_foo, 0);
a.recycle();
}
// this will return "Cat" or "Cats" depending on the value of quantity
private String getFooString() {
return getContext().getResources().getQuantityString(fooResId, quantity);
}
}

updated answer for Kotlin
strings.xml
<plurals name="lbl_items_selected">
<item quantity="one">%d item Selected</item>
<item quantity="other">%d items Selected</item>
</plurals>
Kotlin File
resources.getQuantityString(
R.plurals.lbl_items_selected, //plural from strings.xml file
size, //quantity
size //var arg
)
this will return :
if size = 1 : 1 item selected
if size = 2 (or more) : 2(given size) items selected

getQuantityString returns wrong string with 0 value

In an android app, I have the following string resources:
<plurals name="test">
<item quantity="zero">"I have 0 item"</item>
<item quantity="one">"I have 1 item"</item>
<item quantity="other">"I have several items"</item>
</plurals>
And the following line of code:
String text = getResources().getQuantityString(R.plurals.test, 0)
which I would expect to return
I have 0 item
But it actually returns
I have 1 item
Why ?

Quantity Strings are broken on some Plattforms and phones as the issue Tracker and this discussion "Should Plurals and Quantity Strings be used" points out. It depends on many factors which you cannot control (i.e. localization on the phone).
One solution can be to take an external library like this one, which mimes the same functionallity.
Another solution is stated in the documentation of plurals in android. Avoid using it and use "quantity-neutral" formulations like "Books: 1"

Change the code like this
String text = getResources().getQuantityString(R.plurals.test, 0,0);

how to extract the name attribute from string array?

Hi I build a quiz application.
I have the following (values/)question.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string-array name="question">
<item name="correct">A</item>
<item name="wrong">B</item>
<item name="wrong">C</item>
<item name="wrong">D</item>
</string-array>
</resources>
I would like to have a question with four possible answers but when i retrieve my answers in Java.. I don't know which answer is correct. So I decided to use name attribute in the item tags to pass a value of 'correct' or 'wrong' answer.
Is there anyway to get the name along with the tag value?
because when i use String[] test = res.getStringArray(R.array.question); I can only get the value of each item in my array.
or because this is my 1st time in Android. is there other suitable approach to do this?
thanks

You need to use Handler to parse the xml.
to get attribute value, code is :
attributes.getValue("name")
Try these links for reference:
first and
second

I have made many quizzes, and one nice way is to put correct option always on top, right after question. You can use random function to shuffle options while displaying in an activity.

in Activity:
String[] questionArray = getResources().getStringArray(R.id.question);
then you have
questionArray[0] -> A
questionArray[1] -> B
questionArray[2] -> C
questionArray[3] -> D

Is it possible to have placeholders in strings.xml for runtime values?

Is it possible to have placeholders in string values in string.xml that can be assigned values at run time?
Example:
some string PLACEHOLDER1 some more string

Formatting and Styling
Yes, see the following from String Resources: Formatting and Styling
If you need to format your strings using String.format(String, Object...), then you can do so by putting your format arguments in the string resource. For example, with the following resource:
<string name="welcome_messages">Hello, %1$s! You have %2$d new messages.</string>
In this example, the format string has two arguments: %1$s is a string and %2$d is a decimal number. You can format the string with arguments from your application like this:
Resources res = getResources();
String text = String.format(res.getString(R.string.welcome_messages), username, mailCount);
Basic Usage
Note that getString has an overload that uses the string as a format string:
String text = res.getString(R.string.welcome_messages, username, mailCount);
Plurals
If you need to handle plurals, use this:
<plurals name="welcome_messages">
<item quantity="one">Hello, %1$s! You have a new message.</item>
<item quantity="other">Hello, %1$s! You have %2$d new messages.</item>
</plurals>
The first mailCount param is used to decide which format to use (single or plural), the other params are your substitutions:
Resources res = getResources();
String text = res.getQuantityString(R.plurals.welcome_messages, mailCount, username, mailCount);
See String Resources: Plurals for more details.

Supplemental Answer
When I first saw %1$s and %2$d in the accepted answer, it made no sense. Here is a little more explanation.
They are called format specifiers. In the xml string they are in the form of
%[parameter_index$][format_type]
%: The percent sign marks the beginning of the format specifier.
parameter index: This is a number followed by a dollar sign. If you had three parameters that you wanted to insert into the string, then they would be called 1$, 2$, and 3$. The order you place them in the resource string doesn't matter, only the order that you supply the parameters.
format type: There are a lot of ways that you can format things (see the documentation). Here are some common ones:
s string
d decimal integer
f floating point number
Example
We will create the following formatted string where the gray parts are inserted programmatically.
My sister Mary is 12 years old.
string.xml
<string name="my_xml_string">My sister %1$s is %2$d years old.</string>
MyActivity.java
String myString = "Mary";
int myInt = 12;
String formatted = getString(R.string.my_xml_string, myString, myInt);
Notes
I could use getString because I was in an Activity. You can use context.getResources().getString(...) if it is not available.
String.format() will also format a String.
The 1$ and 2$ terms don't need to be used in that order. That is, 2$ can come before 1$. This is useful when internationalizing an app for languages that use a different word order.
You can use a format specifier like %1$s multiple times in the xml if you want to repeat it.
Use %% to get the actual % character.
For more details read the following helpful tutorial: Android SDK Quick Tip: Formatting Resource Strings

When you want to use a parameter from the actual strings.xml file without using any Java code:
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE resources [
<!ENTITY appname "WhereDat">
<!ENTITY author "Oded">
]>
<resources>
<string name="app_name">&appname;</string>
<string name="description">The &appname; app was created by &author;</string>
</resources>
This does not work across resource files, i.e. variables must be copied into each XML file that needs them.

Was looking for the same and finally found the following very simple solution. Best: it works out of the box.
1. alter your string ressource:
<string name="welcome_messages">Hello, <xliff:g name="name">%s</xliff:g>! You have
<xliff:g name="count">%d</xliff:g> new messages.</string>
2. use string substitution:
c.getString(R.string.welcome_messages,name,count);
where c is the Context, name is a string variable and count your int variable
You'll need to include
<resources xmlns:xliff="http://schemas.android.com/apk/res-auto">
in your res/strings.xml.
Works for me. :)

If you want to write percent (%), duplicate it:
<string name="percent">%1$d%%</string>
label.text = getString(R.string.percent, 75) // Output: 75%.
If you write simply %1$d%, you will get the error: Format string 'percent' is not a valid format string so it should not be passed to String.format.
Or use formatted=false" instead.

In Kotlin you just need to set your string value like this:
<string name="song_number_and_title">"%1$d ~ %2$s"</string>
Create a text view on your layout:
<TextView android:text="#string/song_number_and_title"/>
Then do this in your code if you using Anko:
val song = database.use { // get your song from the database }
song_number_and_title.setText(resources.getString(R.string.song_number_and_title, song.number, song.title))
You might need to get your resources from the application context.

In your string file use this
<string name="redeem_point"> You currently have %s points(%s points = 1 %s)</string>
And in your code use as accordingly
coinsTextTV.setText(String.format(getContext().getString(R.string.redeem_point), rewardPoints.getReward_points()
, rewardPoints.getConversion_rate(), getString(R.string.rs)));

However, you should also read Elias Mårtenson's answer on Android plurals treatment of “zero”. There is a problem with the interpretation of certain values such as "zero".

For Multilingual Projects
As someone who has worked on a major white label solution with many and varying languages and configurations per variant, I can say that there's a lot to consider.
Text direction aside, grammar alone can give you some headaches.
For instance can the order of items change thus
<string name="welcome_messages">Hello, %1$s! You have %2$d new messages.</string>
is to be preferred over
<string name="welcome_messages">Hello, %s! You have %d new messages.</string>
but once you work with translators who often don't know what a string or an integer is, let alone what formatting character to use for each type, or people in general who have no idea in what order the parameters are applied in your code, or even you yourself forget that, or things change which then must be updated at multiple places at once, so using MessageFormat like
<string name="welcome_message">Hello, {0}! You have {1} new messages.</string>
MessageFormat(R.string.welcome_message).format("Name", numMessages)
isn't viable either and the idea of having non tech people try to figure out xlift can't even be entertained then the best solution I know so far is to use explicit, named placeholders as such
<string name="placeholder_data" translatable="false">DATA</string>
<string name="placeholder_data" translatable="false">$DATA</string>
<string name="placeholder_data" translatable="false">%DATA%</string>
..or whatever else doesn't conflict with your texts.
And while you could use DOCTYPE like
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE resources [
<!ENTITY placeholder_data "$DATA">
]>
<string name="text_with_data">Your data is &placeholder_data;.</string>
this will not work with separate files for each language.
Thus in your main/res/values/strings.xml provide the placeholders and default strings like this
<resources>
<string name="placeholder_data" translatable="false">$DATA</string>
<string name="placeholder_error" translatable="false">$ERROR</string>
<string name="app_name">The App</string>
<string name="content_loading">loading..</string>
<string name="content_success">success: $DATA</string>
<string name="content_error">error: $ERROR</string>
</resources>
and then in your variant variant/res/values-de/strings.xml
<resources>
<string name="app_name">Die Applikation</string>
<string name="content_loading">Ladevorgang..</string>
<string name="content_success">Erfolg: $DATA</string>
<string name="content_error">Netzwerkkommunikationsfehler: $ERROR</string>
</resources>
and to use it, write something like
textView.text = when (response) {
is Data -> getText(content_success).resolveData(response.data)
is Error -> getText(content_error).resolveError(response.error)
is Loading -> getText(content_loading)
}
with the use of some helper functions like
fun CharSequence.resolveData(data: JsonObject) =
toString().replace(getString(placeholder_data), data.toString())
fun CharSequence.resolveError(error: Throwable) =
toString().replace(getString(placeholder_error), error.toString())
for simply the reason of having a reference for the translation files and development. Hence there should not be a default file per build flavor. Only the single default file and then a file per language x variant.
Now there's also the issue of numeric grammar. This can be solved with plurals but here again the complexity of the xml file increases. And, as pointed out, zero does not work as one would expect. But also you may want to have a limit to which your app counts due to display size limitations or number of pre-rendered images for your UI and need to display 99+ instead of 100. A solution would be to use a helper function like
fun Context.getText(
quantity: Int,
#PluralsRes resIdQuantity: Int,
#StringRes resIdNone: Int? = null,
#StringRes resIdMoreThan: Int? = null,
maxQuantity: Int? = null,
): CharSequence {
if (resIdMoreThan != null && maxQuantity != null && quantity > maxQuantity)
return getText(resIdMoreThan)
return if (resIdNone != null && quantity == 0) return getText(resIdNone)
else resources.getQuantityText(resIdQuantity, quantity)
}
to override and extend the behavior of the plurals resolver.
And if you have optional features per variant then add a res/values/strings-beans.xml like:
<resources>
<string name="placeholder_name" translatable="false">$NAME</string>
<string name="placeholder_count" translatable="false">$COUNT</string>
<string name="beans_content_bean_count_zero">Hello $NAME! You have no beans.</string>
<string name="beans_content_bean_count_one">Hello $NAME! You have one bean.</string>
<string name="beans_content_bean_count_many">Hello $NAME! You have $COUNT beans.</string>
<string name="beans_content_bean_count_more_than_9000">Hello $NAME! You have over $COUNT beans!</string>
<string name="beans_content_bean_count_two">#string/beans_content_bean_count_many</string>
<string name="beans_content_bean_count_few">#string/beans_content_bean_count_many</string>
<string name="beans_content_bean_count_other">#string/beans_content_bean_count_many</string>
<plurals name="beans_content_bean_count">
<item quantity="zero">#string/beans_content_bean_count_zero</item>
<item quantity="one">#string/beans_content_bean_count_one</item>
<item quantity="two">#string/beans_content_bean_count_two</item>
<item quantity="few">#string/beans_content_bean_count_few</item>
<item quantity="many">#string/beans_content_bean_count_many</item>
<item quantity="other">#string/beans_content_bean_count_other</item>
</plurals>
</resources>
while the variant in variant-with-beans/res/value-en/strings-beans.xml only needs to contain
<resources>
<string name="beans_content_bean_count_zero">Hello $NAME! You have no beans.</string>
<string name="beans_content_bean_count_one">Hello $NAME! You have one bean.</string>
<string name="beans_content_bean_count_many">Hello $NAME! You have $COUNT beans.</string>
<string name="beans_content_bean_count_more_than_9000">Hello $NAME! You have over 9000 beans!</string>
</resources>
and language specific overrides can be provided on a per file basis.
To use this, the code can look like this
val name = "Bob"
val beanCount = 3
val limit = 9000
text = getText(
beanCount,
beans_content_bean_count,
beans_content_bean_count_zero,
beans_content_bean_count_more_than_9000,
limit,
)
.resolveCount(beanCount)
.resolveName(name)
which resolves to the outputs
beanCount = 0 -> "Hello Bob! You have no beans."
beanCount = 1 -> "Hello Bob! You have one bean."
beanCount = 3 -> "Hello Bob! You have 3 beans."
beanCount = 9001 -> "Hello Bob! You have over 9000 beans!"
and due to the resulting simplicity of the language specific resource files, they then can be generated with deployment tools from spread sheets or your company's own server endpoints, etc.
I hope you enjoyed my maddening ride into the world of dynamic string resources for Android and hopefully appreciate that you're not the poor fools having to get the same functionality to work on the iOS side of the product which from my experience required python scripts to modify .xcodeproj files and generate swift code.

in res/values/string.xml
<resources>
<string name="app_name">Hello World</string>
<string name="my_application">Application name: %s, package name: %s</string>
</resources>
in java code
String[] args = new String[2];
args[0] = context.getString(R.string.app_name);
args[1] = context.getPackageName();
String textMessage = context.getString(R.string.my_application,(Object[]) args);

You can use MessageFormat:
<string name="customer_address">Wellcome: {0} {1}</string>
In Java code :
String text = MessageFormat(R.string.customer_address).format("Name","Family");
API level 1:
https://developer.android.com/reference/java/text/MessageFormat.html

Yes! you can do so without writing any Java/Kotlin code, only XML by using this small library I created, which does so at buildtime, so your app won't be affected by it: https://github.com/LikeTheSalad/android-stem
Usage
Your strings:
<resources>
<string name="app_name">My App Name</string>
<string name="welcome_message">Welcome to ${app_name}</string>
</resources>
The generated string after building:
<!-- Auto generated during compilation -->
<resources>
<string name="welcome_message">Welcome to My App Name</string>
</resources>

A Direct Kotlin Solution to the problem:
strings.xml
<string name="customer_message">Hello, %1$s!\nYou have %2$d Products in your cart.</string>
kotlinActivityORFragmentFile.kt:
val username = "Andrew"
val products = 1000
val text: String = String.format(
resources.getString(R.string.customer_message), username, products )

Kotlin version of the accepted answer...
val res = resources
val text = String.format(res.getString(R.string.welcome_messages), username, mailCount)