我不知道如何让我的猴子和狗名单打印为十六进制代码以外的任何东西。我想我需要一个toString方法，但我无法让它工作[重复]

问：

我正在为一个 java 类做一个项目，我被困在这个问题上。当我运行程序和测试菜单选项 4 和 5 时，我得到了要打印的列表，但它们打印为 [Dog@42a57993， Dog@75b84c92， Dog@6bc7c054]，而不是打印数组中的实际信息。

import java.util.ArrayList;
import java.util.Scanner;

public class Driver {
    private static ArrayList<Dog> dogList = new ArrayList<Dog>();
    private static ArrayList<Monkey> monkeyList = new ArrayList<Monkey>();

    public static void main(String[] args) {


        initializeDogList();
        initializeMonkeyList();

        Scanner input = new Scanner(System.in); // scanner class object
        char option;
        
        do // loop until user quits program
        {
            displayMenu();
            option = input.next().charAt(0);
            if (option == '1') { // intakeNewDog method is called
                intakeNewDog(input);
            }
            
            else if (option == '2') { // intakeNewMonkey method is called
                intakeNewMonkey(input);

            }
            
            else if (option == '3') { // reserveAnimal method is called
                reserveAnimal(input);
            }
            
            else if (option == '4') { // printAnimals method is called to print the dog list
                printAnimals(option);
            }
            
            else if (option == '5') { // printAnimals method is called to print the monkey list
                printAnimals(option);
            }
            
            else if (option == '6') { // printAnimals method is called to print all available animals
                printAnimals(option);
            }
            
            else if (option == 'q') { // exit message prints and application stops running
                System.out.print("You have exited the application.");
                break;
            }
            
            else { // in the event of an invalid input, tells user and prompts for a new input
                System.out.print("You have entered an invalid input. Please enter a valid input.");
            }
        }
        while (option != 'q');
    }

    // This method prints the menu options
    public static void displayMenu() {
        System.out.println("\n\n");
        System.out.println("\t\t\t\tRescue Animal System Menu");
        System.out.println("[1] Intake a new dog");
        System.out.println("[2] Intake a new monkey");
        System.out.println("[3] Reserve an animal");
        System.out.println("[4] Print a list of all dogs");
        System.out.println("[5] Print a list of all monkeys");
        System.out.println("[6] Print a list of all animals that are not reserved");
        System.out.println("[q] Quit application");
        System.out.println();
        System.out.println("Enter a menu selection");
    }


    // Adds dogs to a list for testing
    public static void initializeDogList() {
        Dog dog1 = new Dog("Spot", "German Shepherd", "male", "1", "25.6", "05-12-2019", "United States", "intake", false, "United States");
        Dog dog2 = new Dog("Rex", "Great Dane", "male", "3", "35.2", "02-03-2020", "United States", "Phase I", false, "United States");
        Dog dog3 = new Dog("Bella", "Chihuahua", "female", "4", "25.6", "12-12-2019", "Canada", "in service", true, "Canada");

        dogList.add(dog1);
        dogList.add(dog2);
        dogList.add(dog3);
    }


    // Adds monkeys to a list for testing
    //Optional for testing
    public static void initializeMonkeyList() {
        Monkey monkey1 = new Monkey("Joe", "male", "2", "6.5", "04-18-2021", "United States", "in service", false, "United States", "Spider Monkey", "16.6", "16.4", "19.0");
        Monkey monkey2 = new Monkey("Bob", "male", "3", "8.5", "07-20-2020", "Brazil", "Phase 4", true, "United States", "Capuchin", "19", "19.4", "15.5");
        Monkey monkey3 = new Monkey("Lisa", "female", "1", "20.0", "07-07-2022", "Nairobi", "in service", true, "Nairobi", "Howler Monkry", "25.2", "14", "13.4");

        monkeyList.add(monkey1);
        monkeyList.add(monkey2);
        monkeyList.add(monkey3);
    
    }


    // Complete the intakeNewDog method
    // The input validation to check that the dog is not already in the list
    // is done for you
    public static void intakeNewDog(Scanner scanner) {
        System.out.println("What is the dog's name?");
        String name = scanner.nextLine();
        for(Dog dog: dogList) {
            if(dog.getName().equalsIgnoreCase(name)) {
                System.out.println("\n\nThis dog is already in our system\n\n");
                return; //returns to menu
            }
        }

        System.out.println("What is the dog's breed?"); // this code is for adding a new dog
        String breed = scanner.nextLine();
        System.out.println("What is the dog's gender?");
        String gender = scanner.nextLine();
        System.out.println("What is the dog's age?");
        String age = scanner.nextLine();
        System.out.println("What is the dog's weight?");
        String weight = scanner.nextLine();
        System.out.println("What is the dog's acquisition date?");
        String acquisitionDate = scanner.nextLine();
        System.out.println("What is the dog's acquisition country?");
        String acquisitionCountry = scanner.nextLine();
        System.out.println("What is the dog's training status?");
        String trainingStatus = scanner.nextLine();
        System.out.println("Is this dog reserved?");
        boolean reserved = scanner.nextBoolean();
        scanner.nextLine();
        System.out.println("Which country is the dog in service?");
        String inServiceCountry = scanner.nextLine();
        
        Dog dog4 = new Dog(name, breed, gender, age, weight, acquisitionDate, acquisitionCountry, trainingStatus, reserved, inServiceCountry);
        dogList.add(dog4);
        System.out.println("Your entry has been added to the Dog List.");
    }


    public static void intakeNewMonkey(Scanner scanner) {
        System.out.println("What is the monkey's name?");
        String name = scanner.nextLine();
        for(Monkey monkey: monkeyList) {
            if(monkey.getName().equalsIgnoreCase(name)) {
                System.out.println("\n\nThis monkey is already in our system\n\n");
                return;
            }
        }
        System.out.println("What is the monkey's gender?"); // the following is to add a new monkey to the system
        String gender = scanner.nextLine();
        System.out.println("What is the monkey's age?");
        String age = scanner.nextLine();
        System.out.println("What is the monkey's weight?");
        String weight = scanner.nextLine();
        System.out.println("What is the monkey's acquisition date?");
        String acquisitionDate = scanner.nextLine();
        System.out.println("What is the monkey's acquisition country?");
        String acquisitionCountry = scanner.nextLine();
        System.out.println("What is the monkey's training status?");
        String trainingStatus = scanner.nextLine();
        System.out.println("Is this monkey reserved?");
        boolean reserved = scanner.nextBoolean();
        System.out.println("Which country is the monkey in service?");
        String inServiceCountry = scanner.nextLine();
        System.out.println("What is the monkey's species?");
        String species = scanner.nextLine();
        System.out.println("What is the tail length?");
        String tailLength = scanner.nextLine();
        System.out.println("What is the height?");
        String height = scanner.nextLine();
        System.out.println("What is the body length?");
        String bodyLength = scanner.nextLine();
        
        Monkey monkey4 = new Monkey(name, gender, age, weight, acquisitionDate, acquisitionCountry, trainingStatus, reserved, inServiceCountry, species, tailLength, height, bodyLength);
        monkeyList.add(monkey4);
        System.out.println("Your entry has been added to the Monkey List.");
  }
    

        
        public static void reserveAnimal(Scanner scanner) {
            scanner.nextLine();
            System.out.println("Enter animal type: ");
            String animalType = scanner.nextLine();
            if (animalType.equalsIgnoreCase("Monkey")) {
                System.out.println("Enter the monkey's acquisition country: ");
                String country = scanner.nextLine();
                for (Monkey obj: monkeyList) {
                    if (obj.getAcquisitionLocation().equalsIgnoreCase(country)) {
                        obj.setReserved(true);
                        System.out.println("This monkey is now reserved.");
                        return;
                    }
                }
            }
        }

        public static void printAnimals(char option) { // print options for dogList, monkeyList, all available animals
            if (option == '4') {
                System.out.println(dogList);
            }
            else if (option == '5') {
                System.out.println (monkeyList);
            }
            else if (option == '6') {
                for (int i = 0; i < dogList.size(); i++) {
                    if (dogList.get(i).getTrainingStatus().equals("in service") && dogList.get(i).getReserved()==false) {
                        System.out.println(dogList.get(i));
                    }
                }
                for (int i = 0; i < monkeyList.size(); i++) {
                    if (monkeyList.get(i).getTrainingStatus().equals("in service") && monkeyList.get(i).getReserved()==false) {
                        System.out.println(monkeyList.get(i));
                    }
                }
            }

        }

}

我试图搜索有关实现 toString 方法的信息，看看我是否可以弄清楚，但没有成功。