Android string array items

Android Essentials: Working with Strings and String Arrays

One poor coding practice that really gets our blood boiling is when developers include raw string content inline in code. Sure, there are occasionally good reasons to do this, especially when writing debug code, but generally speaking, if your Android application relies on string content that is displayed on the screen, this data belongs in the Android resources, not in the code itself.

There are a number of benefits to including string content as a resource, such as:

• It centralizes the strings used by the application in a single location that is easily managed (by the developer or a non-developer).
• Strings can be defined as a resource once, and used throughout the code. Therefore, it will have consistent spelling, case and punctuation.
• Strings can be internationalized easily, allowing your application to support multiple languages with a single application package file (APK).
• Strings don’t clutter up your application code, leaving it clear and easy to maintain.

So let’s talk about how to add strings and more importantly, string array resources to your applications effectively.

Step 1: Define String Resources for Individual Strings

String resources belong in the /res/values/strings.xml file. Define a string resource entry for each string used by your application. Name your string resources appropriately. For example, the following XML excerpt defines a number of game character race types as individual strings:

Note the “race_” prefix of each string resource. This helps remind team members that these strings may be related somehow. For example, they might be used together an array or displayed as options in a Spinner control.

Step 2: Load Your String Resources Programmatically

You can easily load a string to use in your code using the getString() method of the Resources class. The following code can be dropped into your Activity class to load a String resource defined in your application:

The handy thing about loading resources this way is that if you’ve provided alternative resources in different languages, the appropriate language version of the string will be loaded based upon the device settings at runtime. No special code is needed for this to work.

Step 3: Define String Array Resources Using String Resource References

Now let’s say you wanted to create an array of those character race strings. Sure, you could load them all up individually in the Java code and make a String array in memory, but you would need to know each of the resource’s full id names and reference it in the code. Instead, your best bet is to create a string array resource that references the individual string resources you’ve already created, tying them together.

String array resources are best stored in the /res/values/arrays.xml file. Define a string array with an item for each string used by your application. Name your string array resources appropriately. For example, the following XML excerpt defines an array that contains each of the game character race types defined in the strings.xml resource file in Step 1:

Step 4: Load Your String Array Resources Programmatically

You can easily load a string array to use in your code using the getStringArray() method of the Resources class. The following code can be dropped into your Activity class to load an array resource defined in your application:

Step 5: Referencing Array Resources in Simple Spinner Controls

One useful reason to go through all this work is to populate a control that requires a data adapter, the simplest of which is an array. If you are unfamiliar with using data adapters to populate Spinner controls and the like, check out the Android Developer website’s Hello Spinner tutorial. However, the method described in the linked tutorial is not as easily internationalized as what we are describing in this quick tut, since it defines the raw string contents in the string array resource, instead of as string references.

Using string array resources allows you to skip the steps of hooking up your data adapter to your control. For example, a simple Spinner control, or dropdown, can be populated with a string array resource without bothering with pesky adapters. You simply add a Spinner control to your layout file and set its android:entries attribute to the string array you created and you’re done. For example:

This defines a Spinner control that will show each of the character race strings as options, as shown in Figure 1.

In your Activity class, you can now implement an OnItemSelectedListener to capture when the user selects a specific character race, like this:

Here we simply react whenever an item in the Spinner is selected. We look up the data selected using the getItemAtPosition() method, which, in the case of a string array resource, is the string data itself.

Conclusion

There’s absolutely no reason to define strings and arrays of strings inline in code. Strings and string arrays belong in your Android application resources, not cluttering up your elegant Java. There are a number of benefits to storing string data in resource files, including better organization and easier internationalization. String arrays are even more powerful when they are comprised of string resource references instead of the raw string data. String array resources can be glued to many UI controls that generally rely upon data adapters without a lot of fuss, making your code even more readable and maintainable.

As always, we look forward to your feedback.

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String resources

A string resource provides text strings for your application with optional text styling and formatting. There are three types of resources that can provide your application with strings:

String XML resource that provides a single string. String Array XML resource that provides an array of strings. Quantity Strings (Plurals) XML resource that carries different strings for pluralization.

All strings are capable of applying some styling markup and formatting arguments. For information about styling and formatting strings, see the section about Formatting and Styling.

String

A single string that can be referenced from the application or from other resource files (such as an XML layout).

Note: A string is a simple resource that is referenced using the value provided in the name attribute (not the name of the XML file). So, you can combine string resources with other simple resources in the one XML file, under one element.

file location: res/values/filename.xml
The filename is arbitrary. The element’s name is used as the resource ID. compiled resource datatype: Resource pointer to a String . resource reference: In Java: R.string.string_name
In XML: @string/string_name syntax: elements: Required. This must be the root node.

A string, which can include styling tags. Beware that you must escape apostrophes and quotation marks. For more information about how to properly style and format your strings see Formatting and Styling, below.

name String. A name for the string. This name is used as the resource ID. example: XML file saved at res/values/strings.xml :

This layout XML applies a string to a View:

This application code retrieves a string:

Kotlin

You can use either getString(int) or getText(int) to retrieve a string. getText(int) retains any rich text styling applied to the string.

String array

An array of strings that can be referenced from the application.

Note: A string array is a simple resource that is referenced using the value provided in the name attribute (not the name of the XML file). As such, you can combine string array resources with other simple resources in the one XML file, under one element.

file location: res/values/filename.xml
The filename is arbitrary. The element’s name is used as the resource ID. compiled resource datatype: Resource pointer to an array of String s. resource reference: In Java: R.array.string_array_name
In XML: @[package:]array/string_array_name syntax: elements: Required. This must be the root node.

Defines an array of strings. Contains one or more elements.

name String. A name for the array. This name is used as the resource ID to reference the array. A string, which can include styling tags. 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: XML file saved at res/values/strings.xml :

This application code retrieves a string array:

Kotlin

Quantity strings (plurals)

Different languages have different rules for grammatical agreement with quantity. In English, for example, the quantity 1 is a special case. We write «1 book», but for any other quantity we’d write «n books». This distinction between singular and plural is very common, but other languages make finer distinctions. The full set supported by Android is zero , one , two , few , many , and other .

The rules for deciding which case to use for a given language and quantity can be very complex, so Android provides you with methods such as getQuantityString() to select the appropriate resource for you.

Although historically called «quantity strings» (and still called that in API), quantity strings should only be used for plurals. It would be a mistake to use quantity strings to implement something like Gmail’s «Inbox» versus «Inbox (12)» when there are unread messages, for example. It might seem convenient to use quantity strings instead of an if statement, but it’s important to note that some languages (such as Chinese) don’t make these grammatical distinctions at all, so you’ll always get the other string.

The selection of which string to use is made solely based on grammatical necessity. In English, a string for zero is ignored even if the quantity is 0, because 0 isn’t grammatically different from 2, or any other number except 1 («zero books», «one book», «two books», and so on). Conversely, in Korean only the other string is ever used.

Don’t be misled either by the fact that, say, two sounds like it could only apply to the quantity 2: a language may require that 2, 12, 102 (and so on) are all treated like one another but differently to other quantities. Rely on your translator to know what distinctions their language actually insists upon.

It’s often possible to avoid quantity strings by using quantity-neutral formulations such as «Books: 1». This makes your life and your translators’ lives easier, if it’s an acceptable style for your application.

Note: A plurals collection is a simple resource that is referenced using the value provided in the name attribute (not the name of the XML file). As such, you can combine plurals resources with other simple resources in the one XML file, under one element.

file location: res/values/filename.xml
The filename is arbitrary. The

element’s name is used as the resource ID. resource reference: In Java: R.plurals.plural_name syntax: elements: Required. This must be the root node.

A collection of strings, of which, one string is provided depending on the amount of something. Contains one or more elements.

name String. A name for the pair of strings. This name is used as the resource ID. 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.

quantity Keyword. A value indicating when this string should be used. Valid values, with non-exhaustive examples in parentheses:

Value	Description
zero	When the language requires special treatment of the number 0 (as in Arabic).
one	When the language requires special treatment of numbers like one (as with the number 1 in English and most other languages; in Russian, any number ending in 1 but not ending in 11 is in this class).
two	When the language requires special treatment of numbers like two (as with 2 in Welsh, or 102 in Slovenian).
few	When the language requires special treatment of «small» numbers (as with 2, 3, and 4 in Czech; or numbers ending 2, 3, or 4 but not 12, 13, or 14 in Polish).
many	When the language requires special treatment of «large» numbers (as with numbers ending 11-99 in Maltese).
other	When the language does not require special treatment of the given quantity (as with all numbers in Chinese, or 42 in English).

example: XML file saved at res/values/strings.xml :

XML file saved at res/values-pl/strings.xml :

Kotlin

When using the getQuantityString() method, you need to pass the count twice if your string includes string formatting with a number. For example, for the string %d songs found , the first count parameter selects the appropriate plural string and the second count parameter is inserted into the %d placeholder. If your plural strings do not include string formatting, you don’t need to pass the third parameter to getQuantityString .

Format and style

Here are a few important things you should know about how to properly format and style your string resources.

Handle special characters

When a string contains characters that have special usage in XML, you must escape the characters according to the standard XML/HTML escaping rules. If you need to escape a character that has special meaning in Android you should use a preceding backslash.

By default Android will collapse sequences of whitespace characters into a single space. You can avoid this by enclosing the relevant part of your string in double quotes. In this case all whitespace characters (including new lines) will get preserved within the quoted region. Double quotes will allow you to use regular single unescaped quotes as well.

Any of the following:

• \’
• Enclose the entire string in double quotes ( «This’ll work» , for example)

Character	Escaped form(s)
@	\@
?	\?
New line	\n
Tab	\t
U+XXXX Unicode character	\uXXXX
Single quote ( ‘ )
Double quote ( » )	\» Note that surrounding the string with single quotes does not work. Whitespace collapsing and Android escaping happens after your resource file gets parsed as XML. This means that (space, punctuation space, Unicode Em space) all collapse to a single space ( » » ), because they are all Unicode spaces after the file is parsed as an XML. To preserve those spaces as they are, you can either quote them ( » » ) or use Android escaping ( \u0032 \u8200 \u8195 ). Note: From XML parser’s perspective, there is no difference between «Test this» and «Test this» whatsoever. Both forms will not show any quotes but trigger Android whitespace-preserving quoting (that will have no practical effect in this case). Formatting strings If you need to format your strings, then you can do so by putting your format arguments in the string resource, as demonstrated by the following example resource. In this example, the format string has two arguments: %1$s is a string and %2$d is a decimal number. Then, format the string by calling getString(int, Object. ) . For example: Kotlin Styling with HTML markup You can add styling to your strings with HTML markup. For example: The following HTML elements are supported: Bold: , Italic: , , 25% larger text: 20% smaller text: Setting font properties: . Examples of possible font families include monospace , serif , and sans_serif . Setting a monospace font family: Strikethrough: , , Underline: Superscript: Subscript: Bullet points: , Line breaks: Division: If you aren’t applying formatting, you can set TextView text directly by calling setText(java.lang.CharSequence) . In some cases, however, you may want to create a styled text resource that is also used as a format string. Normally, this doesn’t work because the format(String, Object. ) and getString(int, Object. ) methods strip all the style information from the string. The work-around to this is to write the HTML tags with escaped entities, which are then recovered with fromHtml(String) , after the formatting takes place. For example: Store your styled text resource as an HTML-escaped string: In this formatted string, a element is added. Notice that the opening bracket is HTML-escaped, using the notation. Then format the string as usual, but also call fromHtml(String) to convert the HTML text into styled text: Kotlin Because the fromHtml(String) method formats all HTML entities, be sure to escape any possible HTML characters in the strings you use with the formatted text, using htmlEncode(String) . For instance, if you are formatting a string that contains characters such as » fromHtml(String) , the characters come out the way they were originally written. For example: Kotlin Styling with spannables A Spannable is a text object that you can style with typeface properties such as color and font weight. You use SpannableStringBuilder to build your text and then apply styles defined in the android.text.style package to the text. You can use the following helper methods to set up much of the work of creating spannable text: Kotlin The following bold , italic , and color methods wrap the helper methods above and demonstrate specific examples of applying styles defined in the android.text.style package. You can create similar methods to do other types of text styling. Kotlin Here’s an example of how to chain these methods together to apply various styles to individual words within a phrase: Kotlin The core-ktx Kotlin module also contains extension functions that make working with spans even easier. You can check out the android.text package documentation on GitHub to learn more. For more information on working with spans, see the following links: Styling with annotations Applying a custom typeface to the word “text” in all languages Example — adding a custom typeface Load the string resource and find the annotations with the font key. Then create a custom span and replace the existing span. Kotlin If you’re using the same text multiple times, you should construct the SpannableString object once and reuse it as needed to avoid potential performance and memory issues. For more examples of annotation usage, see Styling internationalized text in Android Annotation spans and text parceling Because Annotation spans are also ParcelableSpans , the key-value pairs are parceled and unparceled. As long as the receiver of the parcel knows how to interpret the annotations, you can use Annotation spans to apply custom styling to the parceled text. To keep your custom styling when you pass the text to an Intent Bundle, you first need to add Annotation spans to your text. You can do this in the XML resources via the tag, as shown in the example above, or in code by creating a new Annotation and setting it as a span, as shown below: Kotlin Retrieve the text from the Bundle as a SpannableString and then parse the annotations attached, as shown in the example above. Kotlin For more information on text styling, see the following links: Content and code samples on this page are subject to the licenses described in the Content License. Java is a registered trademark of Oracle and/or its affiliates. Источник Читайте также:  Компас для android чертежи Оцените статью Вам также может понравиться Как деактивировать режим наушников на смартфоне с Android? 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