How do I solve int cannot be converted to int[]?

I created a java program for a board game called Mastermind. I have created the class called Mastermind and called it in the my main method. I tried inputting numbers from the array I created but it giving me an error of it unable to find the symbol when I tried calling Mastermind. I switched it something else after and stated it as guessResult = Mastermind.attempt(guess[2]); . Now I have an error of int cannot be converted to int[]?, how do I solve this?

import java.util.Scanner;

public class MastermindGame
{
    public static void main(String[] args)
    {
        //game instructions
        System.out.print("Welcome to Mastermind!");
        System.out.print("The computer will generate a passcode with your specified number of digits.");
        System.out.print("Your job is to break that code!");
        System.out.print("After each guess, the computer will tell you how many correct digits are in the correct position.");
        System.out.print("It will do this by printing one X for each correct digit.");
        System.out.print("It does not tell you which digit is correct.");
        System.out.println("If you do not see any Xs print, none of your digits were correct.");
        System.out.println("GOOD LUCK!");
        
        //ask user to determine how many digits the code will be
        System.out.println("How many digits would you like the code to be?");
        //enable input from the user
        Scanner in = new Scanner(System.in);
        //read the integer the user types
        int length = in.nextInt();
        //create the new game with the indicated number of digits
        Mastermind game = new Mastermind(length);
        
        //ssshh!! cheating so we can see if this works!
        System.out.println("Shhh! Just so we know if our program works, the code is ");
        game.printCode();
        
        //set up an array to hold the user's guesses
        int[] guess = {1, 2, 3, 4};
        
        //set up a String to display the result of the guess
        String guessResult = " ";
        
                
        //allow the user 4 tries to break the code
        for (int j = 0; j < 4; j++)
        {
            //tell the user to take a guess
            System.out.println("Gander a guess");
            //loops as many digits (length) as they indicated the code should be
            for (int i = 0; i < 4; i++)
            {
                //ask the user to input their guess for this digit
                System.out.println(" What is the next digit for the code");
                //store their guess in the guess array
                guess[i] = in.nextInt();
            }
            //call the method in the Mastermind class that checks their guess against the code
            guessResult = Mastermind(2);
            //it will print out as many Xs as correct digits, order irrelevant
            System.out.println ( guessResult);
            
            //if the user guess, game over so end the main method with "return"
            if (guessResult.equals("YOU WIN!!"))
                return;
        }
        //if we get outside the loop, user wasn't able to guess, "game over"
        System.out.println("~~~GAME OVER~~~");
    }
}

class Mastermind
{
    private int[] code;
    
    //overloaded constructor
    public Mastermind(int length)
    {
        //get the length of the array to the number of digits the user requested
        code = new int[length];
        
        //walk through the code
        for (int i = 0; i < code.length; i++)
        {
            //add a random digit (0-2 in this case) to the code
            code[i] =  (int)(Math.random()*3 + 0);
        }
    }
    
    //method to check the user's guess against the code
    public String attempt(int[] guess)
    {
        String response = "";
        boolean verify = true;
        
        //walk through the guess array
        for (int k = 4; k < 4; k++)
        {
            //compare guess array to code
            //if digits are the same, add an X to response string
            if (code == guess)
               response += "X";
            //if digits are not equal, set verify to false because the guess is not the code
            else
                verify = false;
        }
        
        //if verify was never set to false, then the user guessed correctly so return YOU WIN
        if ( guess== code)
            return "YOU WIN!!";
        
        //if code gets here, user did not guess correctly, return the String with Xs for correct number of digits.
        return "X";
    }
    
    //created this method so we can cheat to check that our game works
    public void printCode()
    {
        String answer = "";
        //walk through code, concatenating the digit to the answer string
        for (int i = 0; i < code.length; i++)
        {
            answer += code[i] + " ";
        }
        //print the code
        System.out.println(answer);
    }
}

Here is a functional version of your code:

import java.util.Arrays;
import java.util.Scanner;
public class MastermindGame {
public static void main(String[] args) {
// game instructions
System.out.println("Welcome to Mastermind!");
System.out.println("The computer will generate a passcode with your specified number of digits.");
System.out.println("Your job is to break that code!");
System.out.println("After each guess, the computer will tell you how many correct digits are in the correct position.");
System.out.println("It will do this by printing one X for each correct digit.");
System.out.println("It does not tell you which digit is correct.");
System.out.println("If you do not see any Xs print, none of your digits were correct.");
System.out.println("GOOD LUCK!");
// ask user to determine how many digits the code will be
System.out.println("How many digits would you like the code to be?");
// enable input from the user
Scanner in = new Scanner(System.in);
// read the integer the user types
int length = in.nextInt();
// create the new game with the indicated number of digits
Mastermind game = new Mastermind(length);
// ssshh!! cheating so we can see if this works!
System.out.print("Shhh! Just so we know if our program works, the code is ");
game.printCode();
// set up an array to hold the user's guesses
int[] guess = new int[length];
// allow the user 4 tries to break the code
for (int j = 0; j < 4; j++) {
// tell the user to take a guess
System.out.println("Gander a guess");
// loops as many digits (length) as they indicated the code should be
for (int i = 0; i < length; i++) {
// ask the user to input their guess for this digit
System.out.print(" What is the next digit for the code?\n  ");
// store their guess in the guess array
guess[i] = in.nextInt();
}
// call the method in the Mastermind class that checks their guess against the code
int guessResult = game.attempt(guess);
if (guessResult < 0) {
System.out.println("YOU WIN!!");
return;
} else {
System.out.print(" ");
for (int i = 0; i < guessResult; i++)
System.out.print("X");
System.out.print("\n\n");
}
}
// if we get outside the loop, user wasn't able to guess, "game over"
System.out.println("~~~GAME OVER~~~");
}
}
class Mastermind {
private final int[] code;
// overloaded constructor
public Mastermind(int length) {
//get the length of the array to the number of digits the user requested
code = new int[length];
// walk through the code
for (int i = 0; i < code.length; i++) {
//add a random digit (0-2 in this case) to the code
code[i] = (int) (Math.random() * 3 + 0);
}
}
// method to check the user's guess against the code
public int attempt(int[] guess) {
if (Arrays.equals(guess, code)) {
// Return -1 if the player win
return -1;
} else {
int correctDigits = 0;
for (int i = 0; i < code.length; i++) {
if (code[i] == guess[i]) {
correctDigits++;
}
}
return correctDigits;
}
}
// created this method, so we can cheat to check that our game works
public void printCode() {
StringBuilder answer = new StringBuilder();
// walk through code, concatenating the digit to the answer string
for (int j : code) {
answer.append(j);
answer.append(" ");
}
// Remove the last space
String answerString = answer.substring(0, answer.length() - 1);
// print the code
System.out.println(answerString);
}
}