dynamic String using String.xml?

问题:

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

回答1:

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.

回答2:

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

回答3:

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.

回答4:

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. :)

回答5:

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".

回答6:

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:id="@+id/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.

回答7:

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);

回答8:

Kotlin version of the accepted answer...

val res = resources
val text = String.format(res.getString(R.string.welcome_messages), username, mailCount)

回答9:

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