Could not find or load main class in java animal guessing game

Question

I keep getting this error message

Error: Could not find or load main class Animals.Animals Java Result: 1

I don't think I did anything wrong to my program. I can't even find where I did something wrong. Here's my program:

package Animals;

import java.util.*;
public class Animals {

  private static final Scanner keyboard = new Scanner(System.in);

public static void introduction() {
    System.out.println("WELCOME TO GUESS THE ANIMAL GAME");
    System.out.println("If I am correct press Y and if I am wrong press N");
    System.out.println("Ready? Let's begin!");
    System.out.println("-------------------------------------------------");
}

public static void letsPlay(AnimalNode<String> latest) {
    while (!latest.correct()) {
        if (query(latest.getAnimal())) {
            latest = latest.getleft();
        } else {
            latest = latest.getright();
        }
    }
    System.out.println("Is it a " + latest.getAnimal());
    if (!query("\nY or N?")) {
        question(latest);
    } else {
        System.out.println("Winner!");
    }
}

public static AnimalNode<String> AnimalTree() {
    AnimalNode<String> root;
    AnimalNode<String> child;
    final String rootQuestion = "dog";
    final String animal = "dog";

    root = new AnimalNode<String>(rootQuestion, null, null);
    return root;
}

public static void question(AnimalNode<String> latest) {
    String setAnimal;
    String correctAnimal;
    String characteristic;

    setAnimal = latest.getAnimal();
    System.out.println("What is the correct answer? ");
    correctAnimal = keyboard.nextLine();

    System.out.println("What's a characteristic of " + correctAnimal
            + " that is different from " + setAnimal);
    characteristic = keyboard.nextLine();

    latest.setAnimal(characteristic);
    System.out.println("A " + correctAnimal + characteristic);
    if (query("Correct?")) {
        latest.setLeft(new AnimalNode<String>(correctAnimal, null, null));
        latest.setRight(new AnimalNode<String>(correctAnimal, null, null));

    }
}

public static boolean query(String ask) {
    String answer;
    System.out.println(ask + "Y or N: ");
    answer = keyboard.nextLine().toLowerCase();
    while (!answer.startsWith("y") && !answer.startsWith("n")) {
        System.out.println("Press the correct letter");
        System.out.println("Let's try again");
    }
    return answer.startsWith("y");
}

public static void main(String[] args) {
    AnimalNode<String> root;
    introduction();
    root = AnimalTree();

    do {
        letsPlay(root);
    } while (query("-------------------------------------------------"
            + "\nPlay again?"));
}

}

Answer 1

The Animals class MUST be in the Animals directory...

\src
    \Animals
        Animals.java

It must have the package decleation of package Animals

package Animals;
// imports
public class Animals {
    //...

You can compile it from within the Animals directory, but it would probably be safer to compile it in the parent directory...

javac -cp Animals Animals\*.java

You then need to use the fully qualified class name to run it (from the parent directly of Animals...)

java Animals.Animals