The filename or extension is too long

I used the built-in GWT compiler (2.5.0) in Eclipse 4.2.1. After a few hours compilation, I finally got the following error. Any suggestion will be greatly appreciated.

  Compiling 2 permutations
      [ERROR] Unable to start external process
java.io.IOException: Cannot run program "C:\Program Files\Java\jdk1.6.0_38\jre\bin\java": CreateProcess error=206, The filename or extension is too long
    at java.lang.ProcessBuilder.start(ProcessBuilder.java:460)
    at com.google.gwt.dev.ExternalPermutationWorkerFactory.launchExternalWorker(ExternalPermutationWorkerFactory.java:278)
    at com.google.gwt.dev.ExternalPermutationWorkerFactory.getWorkers(ExternalPermutationWorkerFactory.java:366)
    at com.google.gwt.dev.PermutationWorkerFactory.createWorkers(PermutationWorkerFactory.java:366)
    at com.google.gwt.dev.PermutationWorkerFactory.compilePermutations(PermutationWorkerFactory.java:267)
    at com.google.gwt.dev.CompilePerms.compile(CompilePerms.java:207)
    at com.google.gwt.dev.Compiler.run(Compiler.java:242)
    at com.google.gwt.dev.Compiler.run(Compiler.java:198)
    at com.google.gwt.dev.Compiler$1.run(Compiler.java:170)
    at com.google.gwt.dev.CompileTaskRunner.doRun(CompileTaskRunner.java:88)
    at com.google.gwt.dev.CompileTaskRunner.runWithAppropriateLogger(CompileTaskRunner.java:82)
    at com.google.gwt.dev.Compiler.main(Compiler.java:177)

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