This is the problem section, it thinks "unexpected token: {" when there's no brackets out of place :( I've gone over it like 20 times


char lastChar = entered.charAt(entered.length()-1 ); 

  if (lastChar == '?') {         
     lastChar = entered.charAt(entered.length()-3);

                             } 
  if (lastChar == ('a', 'b', 'c', 'd') {         // WHYTHEFUCK CAN'T I USE MULTIPLE LETTERS?!?!
       fill(0,255,0);  text("YES", 300, 200);

                                            }
   else {
       text("NO", 300, 200);
         }

      //       }   this is the only off bracket, for the  void draw

*********************************************************************************************************

  if (lastChar == ('a', 'b', 'c', 'd')      //This doesn't work... anyone know the right way?




Entire Code below, thanks for your time either way. (God it's messy in this format)
********************************************************************************************************


PFont z;
String USERINPUT="    ";
String entered = "    ";



void setup() {
   size(1000,500);

   z = createFont("Arial",20,true);
}
 
 void draw() {
  background(0);
   stroke(255); //Outline color
     textFont(z, 30);         //and color it
     fill(255);
  int x = 75;               //First char is at 75
  text("Simple AI protocol, ask a yes or no question (Type and press enter)", 30, 30);
    text(USERINPUT,50,90);
  text(entered,200,130);


char lastChar = entered.charAt(entered.length()-1 );  //lastChar = last charachter entered, returns: StringIndexOutOfBoundsException: String index out of range: whatever number the string is long// 

  if (lastChar == '?') {          //if it's a ? then go to the second to last char //CANNOT CONVERT FROM CHAR TO BOOLEAN //once == is made, incompatible operand types char and string, // meaning it needs to be single quotes 'a' NOT "a"
     lastChar = entered.charAt(entered.length()-3);  //remember, it starts counting at 0, so -1 is the last, -2 is secondToLast (-3 to skip the shift keypress

                       } 
  if (lastChar == ('a') {         //, WHYTHEFUCK CAN'T I USE MULTIPLE LETTERS?!?!
       fill(0,255,0);  text("YES", 300, 200);
//    if (lastChar == ('')  {return:}It should not start with No on the screen
                        }
   else {
       text("NO", 300, 200);
        }

             }   //and when it decides there's an "Unexpected token: { bracket for no reason....


void keyPressed() {
  if (key == '\n' ) {    // If the return key is pressed, save the String and clear it \n = newline
    entered = USERINPUT; // A String can be cleared by setting it equal to ""
    USERINPUT = "";
  } else {
    // Otherwise, concatenate the String
    // Each character typed by the user is added to the end of the String variable.
    USERINPUT = USERINPUT + key;
  }
}