我正在用java开发一个虚拟狗类。狗应该增加和/或减少某些属性，如卫生，快乐和能源的基础上，某些行动，如吃饭，清洁，玩耍。所有的狗的属性应该在1-100范围内（这是我有问题弄清楚）。如果超出该范围，则应播放警告限制消息。在此之前，我尝试过以下代码和更多代码，但我似乎总是出错，比如负数。
这是我的完整代码，请忽略main类和main方法，看看virtualpet类：

import java.util.Scanner;

public class VirtualPetProgram {
    public static void main(String[] args) {
        // Initialize the Scanner
        Scanner input = new Scanner(System.in);
        int option;

        // Start the user experience
        System.out.println("Welcome to the Virtual Pet Program!");
        System.out.print("What would you like to name your pet? ");

        VirtualPet pet = new VirtualPet(input.nextLine());

        do {
            System.out.println("\n-----------------------------------------------------------------");
            System.out.println("Please enter the integer for the option you choose:");
            System.out.println("  1. Check statuses");
            System.out.println("  2. Feed your virtual pet");
            System.out.println("  3. Play with your virtual pet");
            System.out.println("  4. Clean your virtual pet");
            System.out.println("  5. End program");
            System.out.print("\nYour choice: ");

            // Get the choice from the user.
            option = input.nextInt();

            switch (option) {
                case 1:     // Check statuses
                    // Retrieve the values using the Getter methods.
                    System.out.println("\nValues for " + pet.getName());
                    System.out.println("  Happiness: " + pet.getHappiness());
                    System.out.println("  Energy: " + pet.getEnergy());
                    System.out.println("  Hygiene: " + pet.getHygiene());
                    break;
                case 2:     // Feed your virtual pet
                    // Call feed() instance method. VirtualPet's feed() method should be doing all the work.
                    if (pet.feed()) {
                        System.out.println("\nYou fed " + pet.getName() + ".");
                    } else {
                        System.out.println("\nYou couldn't feed " + pet.getName() + " due to a restriction.");
                    }
                    break;
                case 3:     // Play with your virtual pet
                    // Call play() instance method. VirtualPet's play() method should be doing all the work.
                    if (pet.play()) {
                        System.out.println("\nYou played with " + pet.getName() + ".");
                    } else {
                        System.out.println("\nYou couldn't play with " + pet.getName() + " due to a restriction.");
                    }
                    break;
                case 4:     // Clean your virtual pet
                    // Call clean() instance method. VirtualPet's clean() method should be doing all the work.
                    if (pet.clean()) {
                        System.out.println("\nYou cleaned " + pet.getName() + ".");
                    } else {
                        System.out.println("\nYou couldn't clean " + pet.getName() + " due to a restriction.");
                    }
                    break;
                case 5:     // End program
                    // Display a summary depending on how high the happiness is.
                    System.out.println("Thank you for playing! Here is a summary of your pet's experience:");
                    if (pet.getHappiness() >= 100) {
                        System.out.println("  You did a PERFECT job! Your pet loves you!");
                    } else if (pet.getHappiness() >= 80) {
                        System.out.println("  You did pretty well! Your pet likes you.");
                    } else if (pet.getHappiness() >= 60) {
                        System.out.println("  You did okay. Your pet isn't as happy as it could be.");
                    } else {
                        System.out.println("  You could have done a lot better. Your pet isn't very happy.");
                    }
                    break;
                default:        // User selected an invalid option.
                    System.out.println("\nPlease select a valid option.");
            }
        } while (option != 5);

    }
}

class VirtualPet {
//the attributes should start with the following values:
    private int happiness = 25;
    private int hygiene = 50;
    private int energy = 25;
    private String name;
    public static final String DEFAULT_NAME = "Jackie";

//the constructor
    public VirtualPet(int newHappiness, int newHygiene, int newEnergy) {
        happiness = newHappiness;
        hygiene = newHygiene;
        energy = newEnergy;
    }

// the constructor for the name
    public VirtualPet(String newName) {
        name = newName;
    }

//getter and setter method to keep the dog's
//name below 30 characters otherwise it
//invokes the default name.
// I tried to use a separate method for setter
// but for some reason, it didn't work.
//if you have ideas about this issue, I would appreciate it.

    public String getName() {
        if (name.length() < 30) {
            return name;
        } else {
            name = DEFAULT_NAME;
        }
        return name;
    }

    public int getHappiness() {
        return happiness;
    }

    public void setHappiness(int newHappiness) {
        happiness = newHappiness;
    }

    public int getHygiene() {
        return hygiene;
    }

    public void setHygiene(int newHygiene) {
        hygiene = newHygiene;
    }

    public int getEnergy() {
        return energy;
    }

    public void setEnergy(int newEnergy) {
        energy = newEnergy;
    }

// This is where I set up a boolean method
//to return true and increase both happiness
//and energy if the energy is less than 80.
//the upgrade method called here should work
//as validation for the range of the
//attributes between 1-100.

    public boolean feed() {
        upgrade();
        if (energy < 80) {
            happiness += 5;
            energy += 30;
        } else {
            return false;
        }
        return true;
    }

    public boolean play() {
        upgrade();
        if (energy > 30) {
            happiness += 20;
            energy -= 15;
            hygiene -= 30;
        } else {
            return false;
        }
        return true;

    }

    public boolean clean() {
        upgrade();
        if (energy < 70) {
            happiness -= 20;
            hygiene += 50;
        } else {
            return false;
        }
        return true;
    }

// This is the method to validate
//the range of the attributes from 1-100.
//I can't see where or what I am doing wrong

    public boolean upgrade() {
        if (happiness > 0 && happiness < 100) {
            return true;
        }
        if (energy > 0 && energy < 100){
            return true;
        }
        if (hygiene > 0 && hygiene < 100){
            return true;
        }
        else {
            return false;
        }
    }
}