Android 多個DEX錯誤 Multiple dex files define Landroid/support/v7/app/ActionBar$DisplayOptions;

今天在寫程序的時候我的Android Studio 突然編譯錯誤（錯誤提示如下：）后來經過我的幾番折騰發現每一次都要先Clear Project一下然后再Build就可以了，如果你第二次再Build的時候就報錯。后來我就找到了最強的老師（Google）嘗試解決！可惜很遺憾，我在Google上看到的都是Eclipse上的解決方法。並沒有找到我想要的答案，難道要我每一次在Build的時候都要先Clear Project嗎？最后又經過我的幾番折騰我發現在Project Structure--->app--->Properties中有一個選項叫：Incremental Dex (增加的DEX)的值為True,我又新建了一個項目發現默認值是空值，果然把這個改成空值問題就全然解決了！雖然現在我也不知道這一個選項到底是有什么用。

錯誤提示：

 

Information:Gradle tasks [:app:assembleDebug]
:app:preBuild UP-TO-DATE
:app:preDebugBuild UP-TO-DATE
:app:checkDebugManifest
:app:preReleaseBuild UP-TO-DATE
:app:prepareComAndroidSupportAnimatedVectorDrawable2330Library UP-TO-DATE
:app:prepareComAndroidSupportAppcompatV72330Library UP-TO-DATE
:app:prepareComAndroidSupportSupportV42330Library UP-TO-DATE
:app:prepareComAndroidSupportSupportVectorDrawable2330Library UP-TO-DATE
:app:prepareDebugDependencies
:app:compileDebugAidl UP-TO-DATE
:app:compileDebugRenderscript UP-TO-DATE
:app:generateDebugBuildConfig UP-TO-DATE
:app:generateDebugAssets UP-TO-DATE
:app:mergeDebugAssets UP-TO-DATE
:app:generateDebugResValues UP-TO-DATE
:app:generateDebugResources UP-TO-DATE
:app:mergeDebugResources UP-TO-DATE
:app:processDebugManifest UP-TO-DATE
:app:processDebugResources UP-TO-DATE
:app:generateDebugSources UP-TO-DATE
:app:processDebugJavaRes UP-TO-DATE
:app:compileDebugJavaWithJavac
:app:compileDebugNdk UP-TO-DATE
:app:compileDebugSources
:app:preDexDebug UP-TO-DATE
:app:dexDebug
UNEXPECTED TOP-LEVEL EXCEPTION:
com.android.dex.DexException: Multiple dex files define Landroid/support/v7/app/ActionBar$DisplayOptions;
    at com.android.dx.merge.DexMerger.readSortableTypes(DexMerger.java:591)
    at com.android.dx.merge.DexMerger.getSortedTypes(DexMerger.java:546)
    at com.android.dx.merge.DexMerger.mergeClassDefs(DexMerger.java:528)
    at com.android.dx.merge.DexMerger.mergeDexes(DexMerger.java:164)
    at com.android.dx.merge.DexMerger.merge(DexMerger.java:188)
    at com.android.dx.command.dexer.Main.mergeLibraryDexBuffers(Main.java:504)
    at com.android.dx.command.dexer.Main.runMonoDex(Main.java:334)
    at com.android.dx.command.dexer.Main.run(Main.java:277)
    at com.android.dx.command.dexer.Main.main(Main.java:245)
    at com.android.dx.command.Main.main(Main.java:106)
Error:Execution failed for task ':app:dexDebug'.
> com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException:
 Process 'command 'C:\Program Files\Java\jdk1.8.0_73\bin\java.exe'' finished with non-zero exit value 2

 

解決方法：