Java 中的“不可映射的编码字符”警告

Question

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?

Answer 1

尝试使用： javac -encoding ISO-8859-1 file_name.java

Answer 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.";

Answer 3

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

<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>

Answer 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/

Answer 5

put this line in yor file .gradle above the Java conf.

apply plugin: 'java'
compileJava {options.encoding = "UTF-8"}   

Answer 6

Gradle Steps

If you are using Gradle then you can find the line that applies the java plugin:

apply plugin: 'java'

Then set the encoding for the compile task to be UTF-8:

compileJava {options.encoding = "UTF-8"}   

If you have unit tests, then you probably want to compile those with UTF-8 too:

compileTestJava {options.encoding = "UTF-8"}

Overall Gradle Example

This means that the overall gradle code would look something like this:

apply plugin: 'java'
compileJava {options.encoding = "UTF-8"}
compileTestJava {options.encoding = "UTF-8"}

Answer 7

Most of the time this compile error comes when unicode(UTF-8 encoded) file compiling

javac -encoding UTF-8 HelloWorld.java

and also You can add this compile option to your IDE ex: Intellij idea
(File>settings>Java Compiler) add as additional command line parameter

-encoding : encoding Set the source file encoding name, such as EUC-JP and UTF-8.. If -encoding is not specified, the platform default converter is used. ( DOC )

Answer 8

This worked for me:

<?xml version="1.0" encoding="utf-8" ?>
<project name="test" default="compile">
    <target name="compile">
        <javac srcdir="src" destdir="classes" encoding="iso-8859-1" debug="true" />
    </target>
</project>

Answer 9

If you use eclipse (Eclipse can put utf8 code for you even you write utf8 character. You will see normal utf8 character when you programming but background will be utf8 code) ;

1. Select Project
2. Right click and select Properties
3. Select Resource on Resource Panel (Top of right menu which opened after 2.)
4. You can see in Resource Panel , Text File Encoding , select other which you want

PS : this will ok if you static value in code. For Example String test = "İİİİİııııııççççç";

Answer 10

I had the same problem, where the character index reported in the java error message was incorrect. I narrowed it down to the double quote characters just prior to the reported position being hex 094 (cancel instead of quote, but represented as a quote) instead of hex 022. As soon as I swapped for the hex 022 variant all was fine.

Answer 11

如果从命令提示符使用 Maven Build，也可以使用以下命令：

                    mvn -Dproject.build.sourceEncoding=UTF-8

Answer 12

For those wondering why this happens on some systems and not on others (with the same source, build parameters, and so on), check your LANG environment variable . I get the warning/error when LANG=C.UTF-8 , but not when LANG=en_US.UTF-8 .