java - 属于父类(super class)的不同类的对象的ArrayList？

Question

在下面的代码中，“<”和“>”之间应该放置什么，以便我能够添加 Animal 父类(super class)的每个子类的新对象？

package animal;

import javax.swing.JOptionPane;
import java.util.ArrayList;

public class Animal {

    public static void main(String[] args) {
        Animal createAnimals = new Animal();
        createAnimals.userInputHandle();

        ArrayList <> animalList = new ArrayList<>(); 
        animalList.add(new Dog);

    }

    private String userInputHandle(){

        String userInput;
        userInput = JOptionPane.showInputDialog("Select animal from the "
                + "following list"
                + "\n1.Dog\n2.Cat\n3.Snake\n4.Frog"
                + "\n5.Human\n6.Shark\n7.Sea Gulls");
        userInput = userInput.toLowerCase();

    return userInput;}
}

class Fish extends Animal{




}
class Amphibians extends Animal{

}
class Reptiles extends Animal{}
class Birds extends Animal{}

这样我将在 Animal 类中创建一个方法并为每个子类重写它。例如对于两栖类--> Frog 属于两栖类等等。

Answer 1

// this will work fine as 'Animal' will be base class for other class
ArrayList <Animal> animalList = new ArrayList<Animal>(); 
//
animalList.add(new Reptiles());
animalList.add(new Birds());
animalList.add(new Amphibians());