Error: Error converting bytecode to dex

[Ndack]

Hi guys... I faced with this Problem.. For anyone having idea please help me

Information:Gradle tasks [:sample:assembleDebug]
Error:Error converting bytecode to dex:
Cause: com.android.dex.DexException: Multiple dex files define Lfr/ganfra/materialspinner/MaterialSpinner$1;
Error:com.android.dex.DexException: Multiple dex files define Lfr/ganfra/materialspinner/MaterialSpinner$1;
Error: at com.android.dx.merge.DexMerger.readSortableTypes(DexMerger.java:661)
Error: at com.android.dx.merge.DexMerger.getSortedTypes(DexMerger.java:616)
Error: at com.android.dx.merge.DexMerger.mergeClassDefs(DexMerger.java:598)
Error: at com.android.dx.merge.DexMerger.mergeDexes(DexMerger.java:171)
Error: at com.android.dx.merge.DexMerger.merge(DexMerger.java:198)
Error: at com.android.builder.dexing.DexArchiveMergerCallable.call(DexArchiveMergerCallable.java:61)
Error: at com.android.builder.dexing.DexArchiveMergerCallable.call(DexArchiveMergerCallable.java:36)
Error: at java.util.concurrent.ForkJoinTask$AdaptedCallable.exec(ForkJoinTask.java:1424)
Error: at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
Error: at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
Error: at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
Error: at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)
Error:Execution failed for task ':sample:transformDexArchiveWithDexMergerForDebug'.

com.android.build.api.transform.TransformException: com.android.dex.DexException: Multiple dex files define Lfr/ganfra/materialspinner/MaterialSpinner$1;
Information:BUILD FAILED in 2s
Information:15 errors
Information:0 warnings
Information:See complete output in console