Collection 接口的使用

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;

public  class Demo01 {
    public static void main(String[] args) {
        Collection collection = new ArrayList();
        Student s1 = new Student("张三",16);
        Student s2 = new Student("李四",17);
        Student s3 = new Student("王五",18);

        //1.添加元素
        collection.add(s1);
        collection.add(s2);
        collection.add(s3);
        System.out.println(collection);//[Student{name='张三', age=16}, Student{name='李四', age=17}, Student{name='王五', age=18}]
        System.out.println(collection.size());//3

        //2.删除元素
        collection.remove(s1);
        System.out.println(collection);
        System.out.println(collection.size());//2

        //3.遍历元素
          //1.增强for
        for (Object object:
             collection) {
            Student s=(Student) object;
            System.out.println(s);
        }
          //2.迭代器
        Iterator iterator = collection.iterator();
        while (iterator.hasNext()){
            Object next = iterator.next();
            Student s = (Student) next;
            System.out.println(s);
        }

        //4.判断
        System.out.println(collection.contains(s2));//true
        System.out.println(collection.isEmpty());//false

    }
}

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

    public Student() {

    }

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

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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

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