"unmappable character for encoding" warning in Java

I'm currently working on a Java project that is emitting the following warning when I compile:

/src/com/myco/apps/AppDBCore.java:439: warning: unmappable character for encoding UTF8
    [javac]         String copyright = "� 2003-2008 My Company. All rights reserved.";

I'm not sure how SO will render the character before the date, but it should be a copyright symbol, and is displayed in the warning as a question mark in a diamond.

It's worth noting that the character appears in the output artifact correctly, but the warnings are a nuisance and the file containing this class may one day be touched by a text editor that saves the encoding incorrectly...

How can I inject this character into the "copyright" string so that the compiler is happy, and the symbol is preserved in the file without potential re-encoding issues?

Solution 1:

Try with: javac -encoding ISO-8859-1 file_name.java

Solution 2:

Use the "\uxxxx" escape format.

According to Wikipedia, the copyright symbol is unicode U+00A9 so your line should read:

String copyright = "\u00a9 2003-2008 My Company. All rights reserved.";

Solution 3:

If you're using Maven, set the <encoding> explicitly in the compiler plugin's configuration, e.g.

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>2.3.2</version>
            <configuration>
                <encoding>UTF-8</encoding>
            </configuration>
        </plugin>

Solution 4:

This helped for me:

All you need to do, is to specify a envirnoment variable called JAVA_TOOL_OPTIONS. If you set this variable to -Dfile.encoding=UTF8, everytime a JVM is started, it will pick up this information.

Source: http://whatiscomingtomyhead.wordpress.com/2012/01/02/get-rid-of-unmappable-character-for-encoding-cp1252-once-and-for-all/