How to fixed current Unity3D 5.4.1f1 unable to compiled Android projects?

Any one please help! I was trying to compiled my android project with Amazon Ad plugin installed in Unity3D but that was unsuccessful because of many reasons could any one show me how to compiled this under current Unity3D 5.4.1f1 please? Below are debug message!

CommandInvokationFailure: Unable to convert classes into dex format.
C:/NVPACK/jdk1.7.0_71\bin\java.exe -Xmx2048M -Dcom.android.sdkmanager.toolsdir=“C:/Android/android-sdk ools” -Dfile.encoding=UTF8 -jar “C:\Program Files\Unity\Editor\Data\PlaybackEngines\AndroidPlayer/Tools\sdktools.jar” -

stderr[
Exception in thread “main” java.lang.UnsupportedClassVersionError: com/android/dx/command/Main : Unsupported major.minor version 52.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:274)
at SDKMain.main(SDKMain.java:127)
]
stdout[

]
UnityEditor.Android.Command.Run (System.Diagnostics.ProcessStartInfo psi, UnityEditor.Android.WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg)
UnityEditor.Android.AndroidSDKTools.RunCommandInternal (System.String javaExe, System.String sdkToolsDir, System.String sdkToolCommand, Int32 memoryMB, System.String workingdir, UnityEditor.Android.WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg)
UnityEditor.Android.AndroidSDKTools.RunCommandSafe (System.String javaExe, System.String sdkToolsDir, System.String sdkToolCommand, Int32 memoryMB, System.String workingdir, UnityEditor.Android.WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg)
UnityEditor.HostView:OnGUI()

This error is generally caused when there are duplicate files in the project. This is quite common with “Support v4” library file in plugins as it is used is many 3rd party assets. If you have multiple of these for example in your project remove one of them, preferably keeping the most up to date one. There may also occur with other Library files ( .aar / .jar ).