代号一个生成错误：建议“使用-source 7”

Question

I am using Eclipse and Codename One. When I am building my application I am getting the following error:

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Buildfile: C:\P\eclipse_workspace\HelloWorld\build.xml

jar:
        [echo] Compile is forcing compliance to the supported API's/features for maximum device compatibility. This allows smaller
        [echo]          code size and wider device support
        [copy] Copying 3 files to C:\P\eclipse_workspace\HelloWorld\build\tmp
       [javac] C:\P\eclipse_workspace\HelloWorld\build.xml:147: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=last; set to false for repeatable builds
       [javac] Compiling 39 source files to C:\P\eclipse_workspace\HelloWorld\build\tmp
       [javac] warning: [options] source value 1.5 is obsolete and will be removed in a future release
       [javac] warning: [options] target value 1.5 is obsolete and will be removed in a future release
       [javac] warning: [options] To suppress warnings about obsolete options, use -Xlint:-options.
       [javac] C:\P\eclipse_workspace\HelloWorld\src\com\mycompany\lectures\Starter.java:197: error: strings in switch are not supported in -source 1.5
       [javac]      switch(option){
       [javac]            ^
       [javac]   (use -source 7 or higher to enable strings in switch)
       [javac] Note: Some input files use or override a deprecated API.
       [javac] Note: Recompile with -Xlint:deprecation for details.
       [javac] 1 error
       [javac] 3 warnings

BUILD FAILED
C:\P\eclipse_workspace\HelloWorld\build.xml:147: Compile failed; see the compiler error output for details.

Total time: 1 second
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How can I fix this problem in Eclipse?

Thanks!

Answer 1

For a thorough explanation of why this is happening see the explanation below.

When you create a new Codename One project it can either be a Java 8 project or a Java 5 project. If your IDE is running under Java 7 you won't be presented with the Java 8 option at all and a Java 5 project will be created. Switching the IDE to Java 7 will work in the simulator but fail when you try to build for devices!

The best solution is to switch to Java 8, you need to verify that your IDE is using it internally, in eclipse this is a bit tricky as you need to edit the ini file for eclipse .

Once you do that you will be able to create a new project and select Java 8. Alternatively you can just edit the project and configure it to use Java 8 but then don't forget to add the build hint java.version=8 .

You got this specific error because of a switch statement involving a String in your code. It is not supported in Java 5 (the target version used by your compiler).

An alternative workaround is to use if-else statements instead of the switch .

Answer 2

Ensure that you are running the latest Java version Java 8 . You can update here , if necessary.

Open build.xml and do find and replace . Look for 1.5 and replace with 1.7 or 1.8 (though you will have to add a build hint `java.version=8).

Right-click on your project and choose Property , navigate to sources from the left pane and change your source/Binary Format to JDK 7 or JDK 8 (depending on the version you want).

Switch to Libraries right under Sources and change your Java Platform to the latest