IndexOutOfBounds,索引14,大小16.如何？

Question

如果堆栈跟踪显示它实际处于边界内,那么索引如何超出界限？虽然上下文可能并不重要,但我们正在为Netbeans平台上的IDE开发一个Lua解析器/ VM,并且这种情况不断增加.怎么会这样？一些奇怪的并发问题？提前感谢任何见解.

java.lang.IndexOutOfBoundsException: Index: 14, Size: 16
    at java.util.ArrayList.rangeCheck(ArrayList.java:604)
    at java.util.ArrayList.get(ArrayList.java:382)
    at org.netbeans.lib.lexer.BatchTokenList.existingToken(BatchTokenList.java:197)
    at org.netbeans.lib.lexer.BatchTokenList.tokenOffset(BatchTokenList.java:150)
    at org.netbeans.api.lexer.TokenSequence.offset(TokenSequence.java:256)
    at com.MYDevelopers.LuaSupportCompiler.TokenManager.getTokenStart(TokenManager.java:230)
    at com.MYDevelopers.LuaSupportCompiler.CompilationUnit.getCurrentLocation(CompilationUnit.java:459)
    at com.MYDevelopers.LuaSupportCompiler.CompilationUnit.expressionImp(CompilationUnit.java:654)
    at com.MYDevelopers.LuaSupportCompiler.CompilationUnit.expression(CompilationUnit.java:647)
    at com.MYDevelopers.LuaSupportCompiler.CompilationUnit.RHSexpression(CompilationUnit.java:643)
    at com.MYDevelopers.LuaSupportCompiler.CompilationUnit.chunk(CompilationUnit.java:1004)
    at com.MYDevelopers.LuaSupportCompiler.CompilationUnit.compile(CompilationUnit.java:164)
    at com.MYDevelopers.LuaSupportCompiler.CompilationUnit.compileIfRequired(CompilationUnit.java:148)
    at com.MYDevelopers.LuaSupport.LuaProject.CompilationManagers.SourcesManager.compile(SourcesManager.java:222)
    at com.MYDevelopers.LuaSupport.LuaProject.CompilationManagers.SourcesManager.compileAndEvaluateIfRequired(SourcesManager.java:210)
    at com.MYDevelopers.LuaSupport.LuaProject.CompilationManagers.SourcesManager.addSourceManager(SourcesManager.java:113)
    at com.MYDevelopers.LuaSupport.LuaProject.CompilationManagers.SourcesManager.addDirectory(SourcesManager.java:106)
    at com.MYDevelopers.LuaSupport.LuaProject.CompilationManagers.SourcesManager.addBootDirectory(SourcesManager.java:80)
    at com.MYDevelopers.LuaSupport.LuaProject.CompilationManagers.SourcesManager.addBaseLibraries(SourcesManager.java:72)
    at com.MYDevelopers.LuaSupport.LuaProject.CompilationManagers.SourcesManager.<init>(SourcesManager.java:47)
    at com.MYDevelopers.LuaSupport.LuaProject.CompilationManagers.GlobalCompilationManager.addProjectDirectory(GlobalCompilationManager.java:76)
    at com.MYDevelopers.LuaSupport.LuaProject.LuaProject.getSourcesManager(LuaProject.java:309)
    at com.MYDevelopers.LuaSupport.LuaProject.LuaProject$ProjectOpenHookImpl.projectOpened(LuaProject.java:599)
    at org.netbeans.spi.project.ui.ProjectOpenedHook$1.projectOpened(ProjectOpenedHook.java:84)
[catch] at org.netbeans.modules.project.ui.OpenProjectList.notifyOpened(OpenProjectList.java:1138)
    at org.netbeans.modules.project.ui.OpenProjectList.access$1600(OpenProjectList.java:134)
    at org.netbeans.modules.project.ui.OpenProjectList$LoadOpenProjects.loadOnBackground(OpenProjectList.java:434)
    at org.netbeans.modules.project.ui.OpenProjectList$LoadOpenProjects.run(OpenProjectList.java:312)
    at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1452)
    at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2032)

Answer 1

通过阅读源代码ArrayList,您可以看到rangeCheck实现为

 private void rangeCheck(int index) {
   if (index >= size)
     throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
 }

所以我的猜测只是去并发.抛出此异常时,没有其他明显的方法可以获得较小的索引.

在某种情况下,在抛出异常之后,大小会发生变化

• 您尝试从列表中检索超出边界的项目
• 同时另一个线程正在添加另一个元素,因此size在抛出异常时会增加大小
• 最终呈现异常