AS开发中出现Error(四)——Error:Error converting bytecode to dex: Cause: com.android.dex.DexException: Mult

Error:Error converting bytecode to dex:  
Cause: com.android.dex.DexException: Multiple dex files define Lcom/tencent/mm/opensdk/a/a$a;  
Error:Execution failed for task ':app:transformClassesWithDexForDebug'.  
> com.android.build.api.transform.TransformException: com.android.ide.common.process.ProcessException: java.util.concurrent.ExecutionException: java.lang.UnsupportedOperationException  
Error:Execution failed for task ':app:transformClassesWithJarMergingForDebug'.  
> com.android.build.api.transform.TransformException: java.util.zip.ZipException: duplicate entry: com/tencent/mm/opensdk/a/a/a$a.class

原因：
1、两个AndroidManifest.xml的包名重复了
2、另外，Multiple dex files 的情况也有可能是有重复的support包，或者重复的jar
3、或者有种情况是应用了两个jar中有冲突的class

解决：1、在app\build.gradle中添加

android {  
    defaultConfig {  
        ....  
        multiDexEnabled true  
    }  
}  

2、修改主工程与library的包名，删除重复的jar包