【Android】String Resource

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ref:http://developer.android.com/guide/topics/resources/string-resource.html#FormattingAndStyling

Formatting and Styling

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

Escaping apostrophes and quotes

If you have an apostrophe or a quote in your string, you must either escape it or enclose the whole string in the other type of enclosing quotes. For example, here are some stings that do and don't work:

<string name="good_example">"This'll work"</string>
<string name="good_example_2">This\'ll also work</string>
<string name="bad_example">This doesn't work</string>
<string name="bad_example_2">XML encodings don&apos;t work</string>

Formatting strings

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);

Styling with HTML markup

You can add styling to your strings with HTML markup. For example:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="welcome">Welcome to <b>Android</b>!</string>
</resources>

Supported HTML elements include:

• <b> for bold text.
• <i> for italic text.
• <u> for underline text.

Sometimes you may want to create a styled text resource that is also used as a format string. Normally, this won't work because the String.format(String, Object...) method will 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 withfromHtml(String), after the formatting takes place. For example:

1. Store your styled text resource as an HTML-escaped string:

   <resources>
     <string name="welcome_messages">Hello, %1$s! You have &lt;b>%2$d new messages&lt;/b>.</string>
   </resources>

   In this formatted string, a <b> element is added. Notice that the opening bracket is HTML-escaped, using the< notation.
2. Then format the string as usual, but also call fromHtml(String) to convert the HTML text into styled text:

   Resources res = getResources();
   String text = String.format(res.getString(R.string.welcome_messages), username, mailCount);
   CharSequence styledText = Html.fromHtml(text);

Because the fromHtml(String) method will format 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'll be passing a string argument to String.format() that may contain characters such as "<" or "&", then they must be escaped before formatting, so that when the formatted string is passed through fromHtml(String), the characters come out the way they were originally written. For example:

String escapedUsername = TextUtil.htmlEncode(username);
Resources res = getResources();
String text = String.format(res.getString(R.string.welcome_messages), escapedUsername, mailCount);
CharSequence styledText = Html.fromHtml(text);