Execution failed for task ':app:preDexDebug' in android studio?

I am using Android studio 1.3.2.
I am implementing Appium. My OS is Ubuntu.
I tried so many times with Build > clean project, Invalidate crashes and report… but still I am getting the below error:

Execution failed for task ':app:preDexDebug
org.gradle.process.internal.ExecException: Process 'command
’/usr/lib/jvm/java-7-oracle/bin/java’’ finished with non-zero exit
value 1

Can anyone guide me to solve this error?