Java "bad class file" issue

[Ltwolf20]

So I recently attended the 2016 FRC Quick Build and attended the Java programming workshop. After following the code the instructor gave as well as making a few alterations and additions specific to my team's robot, the code shows no errors or alerts, however when I go to run the program through WPILIB Java Deploy it fails and I get this message.

Buildfile: /Users/ProgrammingWolf/Documents/workspace/TestRobot/build.xml
Trying to override old definition of task classloader
clean:
[delete] Deleting directory /Users/ProgrammingWolf/Documents/workspace/TestRobot/build
compile:
[mkdir] Created dir: /Users/ProgrammingWolf/Documents/workspace/TestRobot/build
[echo] [athena-compile] Compiling src with classpath=/Users/ProgrammingWolf/wpilib/java/current/lib/WPILib.jar:/Users/ProgrammingWolf/wpilib/java/current/lib/NetworkTables.jar: to build
[javac] Compiling 8 source files to /Users/ProgrammingWolf/Documents/workspace/TestRobot/build
[javac] /Users/ProgrammingWolf/Documents/workspace/TestRobot/src/org/usfirst/frc/team4796/robot/OI.java:3: cannot access edu.wpi.first.wpilibj.Joystick
[javac] bad class file: edu/wpi/first/wpilibj/Joystick.class(edu/wpi/first/wpilibj:Joystick.class)
[javac] class file has wrong version 52.0, should be 50.0
[javac] Please remove or make sure it appears in the correct subdirectory of the classpath.
[javac] import edu.wpi.first.wpilibj.Joystick;
[javac] ^

BUILD FAILED
/Users/ProgrammingWolf/wpilib/java/current/ant/build.xml:71: Compile failed; see the compiler error output for details.

Total time: 1 second



I am not quite sure how to fix this error.