Format a message using MessageFormat.format() in Java

问题

I have stored some messages in a resource bundle. I'm trying to format these messages as follows.

import java.text.MessageFormat;

String text = MessageFormat.format("You're about to delete {0} rows.", 5);
System.out.println(text);

Assume that the first parameter i.e the actual message is stored in a property file which is somehow retrieved.

The second parameter i.e 5 is a dynamic value and should be placed in the placeholder {0} which doesn't happen. The next line prints,

Youre about to delete {0} rows.

The placeholder is not replaced with the actual parameter.

---

It is the apostrophe here - You're. I have tried to escape it as usual like You\\'re though it didn't work. What changes are needed to make it work?

回答1:

Add an extra apostrophe ' to the MessageFormat pattern String to ensure the ' character is displayed

String text = 
     java.text.MessageFormat.format("You''re about to delete {0} rows.", 5);
                                         ^

An apostrophe (aka single quote) in a MessageFormat pattern starts a quoted string and is not interpreted on its own. From the javadoc

A single quote itself must be represented by doubled single quotes '' throughout a String.

The String You\\'re is equivalent to adding a backslash character to the String so the only difference will be that You\re will be produced rather than Youre. (before double quote solution '' applied)

回答2:

Just be sure you have used double apostrophe ('')

String text = java.text.MessageFormat.format("You''re about to delete {0} rows.", 5);
System.out.println(text);

Edit:

Within a String, a pair of single quotes can be used to quote any arbitrary characters except single quotes. For example, pattern string "'{0}'" represents string "{0}", not a FormatElement. ...

Any unmatched quote is treated as closed at the end of the given pattern. For example, pattern string "'{0}" is treated as pattern "'{0}'".

Source http://docs.oracle.com/javase/7/docs/api/java/text/MessageFormat.html

回答3:

You need to use double apostrophe instead of single in the "You''re", eg:

String text = java.text.MessageFormat.format("You''re about to delete {0} rows.", 5);
System.out.println(text);

回答4:

For everyone that has Android problems in the string.xml, use \'\' instead of single quote.

回答5:

Using an apostrophe ’ (Unicode: \u2019) instead of a single quote ' fixed the issue without doubling the \'.

来源：https://stackoverflow.com/questions/17569608/format-a-message-using-messageformat-format-in-java