Java SubList 类 Java subList方法 Java ArrayList$SubList 方法特点 SubList 用法

article/2025/10/21 20:10:09

Java SubList 类 Java subList方法 Java ArrayList$SubList 方法特点 SubList 用法

一、概述

在java集合中，常用ArrayList类中，若需要对 list进行截取，可以使用subList方法，进行生成 SubList的内部类，那么 ArrayList 和内部类 ArrayList$SubList 有啥区别和关联呢？ArrayList 和 SubList 分别进行操作时候（增、删、改），对原来是有影响变化吗？

java.util.ArrayList.SubList 如下：

二、代码示例

1、ArrayList.subList 方法截取测试

/*** Description: subList 方法测试* @return  void* @version v1.0* @author wu* @date 2022/11/14 10:43*/
@Test
public void subListMethodTest() throws Exception {final ArrayList<String> srcList = Lists.newArrayList("1", "2", "3", "4", "5", "6", "7", "8", "9", "10");final List<String> subList = srcList.subList(2, 5);System.out.println("srcList :" + srcList);System.out.println("subList :" + subList);
}

1.1、输出结果：

srcList :[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
subList :[3, 4, 5]

1.2、根据输出结果可知：根据索引截取，前闭后开 [startIndex,endIndex) ;

2、srcList 进行增删改操作测试

  @Testpublic void srcListTest() throws Exception {final ArrayList<String> srcList = Lists.newArrayList("1", "2", "3", "4", "5", "6", "7", "8", "9", "10");final List<String> subList = srcList.subList(2, 5);System.out.println("srcList :" + srcList);System.out.println("subList :" + subList);/*** 添加和删除，会触发 ConcurrentModificationException 异常* 原因： 会修改 modCount 属性*/srcList.add("333");System.out.println("srcList add :" + srcList);
//        System.out.println("subList :" + subList);//        srcList.remove("3");
//        System.out.println("srcList remove :" + srcList);
//        System.out.println("subList :" + subList);/*** 修改是正常操作，不会修改 modCount 属性 ;* srcList 修改后， subList 会同步修改*/
//        srcList.set(6,"666");
//        srcList.set(3,"333");
//        System.out.println("srcList update :" + srcList);
//        System.out.println("subList :" + subList);}

2.1、输出结果，测试过程略。

3、对 subList 进行增删改操作测试

   @Testpublic void subListTest() throws Exception {final ArrayList<String> srcList = Lists.newArrayList("1", "2", "3", "4", "5", "6", "7", "8", "9", "10");final List<String> subList = srcList.subList(2, 5);System.out.println("srcList :" + srcList);System.out.println("subList :" + subList);subList.add("101");
//        System.out.println("srcList :" + srcList);
//        System.out.println("subList add:" + subList);//        subList.remove("3");
//        System.out.println("srcList :" + srcList);
//        System.out.println("subList remove:" + subList);subList.set(0, "333");System.out.println("srcList :" + srcList);System.out.println("subList update:" + subList);}

3.1、输出结果，测试过程略。

三、总结

1、java.util.ArrayList#subList 方法，特点如下：

根据索引截取，取值区间是：前闭后开
生成的 ArrayList的内部类 SubList

2、srcList.subList() 截取后，会同时存在 srcList 和 subList 2个List对象

srcList: 添加、删除：再使用subList 会触发异常 ConcurrentModificationException；修改操作： subList 同步变化
subList:添加、修改、删除 --- srcList 会同步变化

上述规则，请自行执行【二-代码示例】中的代码，进行验证。

3、subList 方法和 java.lang.String#substring 方法，类似的，截取规则是一样的

String s = "12345678910";
final String substring = s.substring(2, 5);
System.out.println("substring=" + substring);//输出结果：substring=345

更多的有关 java list 集合文章：

https://thinkcode.blog.csdn.net/article/details/126111603

https://thinkcode.blog.csdn.net/article/details/126111838

https://thinkcode.blog.csdn.net/article/details/127629014

https://thinkcode.blog.csdn.net/article/details/127629841