Arduino serial communication input string checking
First, you declare an array of 4 items and provide an initializer for 3. Don't know how it can even compile, maybe it is tolerated but in doubt

String [] array = {"hey","jude","jane","foo"}; 


Also, your serialEvent function appends \n to the string. Even if you receive string jane, you will compare jane from array with jane\n from serial

char inChar = (char)Serial.read();
if( inChar == '\n')
   stringComplete = true;
else
   inputString += inChar