Java 集合框架-ArrayList

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一、整体代码

ArrayListDemo.java

import java.util.*;class Person{    private String name;    private int age;    Person(String name,int age)    {        this.name = name;        this.age = age;    }    public boolean equals(Object obj)    {        if(!(obj instanceof Person))        return false;        Person p = (Person)obj;        return this.name.equals(p.name) && this.age == p.age;    }    public String getName()    {        return name;    }    public int getAge()    {        return age;    }    public String toString()    {        return name+age;    }}public class ArrayListDemo{    public static void sop(Object obj)    {        System.out.println(obj);    }    public static void main(String[] args)    {        ArrayList<Person> al = new ArrayList<Person>();        al.add(new Person("lisi01",30));        al.add(new Person("lisi02",32));        al.add(new Person("lisi02",32));        al.add(new Person("lisi04",35));        al.add(new Person("lisi03",33));        al.add(new Person("lisi04",35));        sop(al);        ArrayList<Person> al1 = singleElement(al);        sop(al1);    }     public static ArrayList<Person> singleElement(ArrayList<Person> al)     {            ArrayList<Person> newAl = new ArrayList<Person>();            Iterator<Person> it = al.iterator();           while(it.hasNext())            {                Person p = it.next();                if(!newAl.contains(p))                newAl.add(p);            }        return newAl;      }}

二、解释

ArrayList顺序加入元素，可以加入重复元素，判断元素是否重复的方法是equal。

代码地址：https://github.com/jltxgcy/Demo