java二十二（List和ArrayList）

一、List把静态数组封装成动态数组。有序列表

二、ArrayList是常用的数组类，有添加，删除，修改多种方法

三、案列

ListDemo.java

package com.kouding;

import java.util.ArrayList;
import java.util.List;

public class ListDemo {
    public static void main(String[] args) {
        // List<泛型> 变量 = new ArrayList<>();
        List<Dog> dogList = new ArrayList<>();
        Dog dog1 = new Dog(1, "菲菲");
        dogList.add(dog1);
        dogList.add(dog1);
        dogList.add(dog1);
        dogList.add(dog1);
    }
}

Dog.java

package com.kouding;

public class Dog {
    private int age;
    private String name;

    public Dog(int age, String name) {
        this.age = age;
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Dog dog = (Dog) o;

        if (age != dog.age) return false;
        return name.equals(dog.name);
    }

    @Override
    public String toString() {
        return "Dog{" +
                "age=" + age +
                ", name='" + name + '\'' +
                '}';
    }

    @Override
    public int hashCode() {
        int result = age;
        result = 31 * result + name.hashCode();
        return result;
    }
}