Correct spelling.

languages/java.md

@@ -85,7 +85,7 @@ int c = a + b;
     double tan(double theta) //tangent of theta
     double toRadians(double degrees) // convert angle from degrees to radians
     double toDegrees(double radians)  // convert angle from radians to degrees
-    double exp(doube a)  // exponential (e^a)
+    double exp(double a)  // exponential (e^a)
     double pow(double a, double p) //raise a to the bth power (a^b)
     double random() //random in [0,1)
     double sqrt(double a)  //square root of a