阶段1 语言基础+高级_1-3-Java语言高级_1-常用API_1_第4节 ArrayList集合_13-ArrayList集合概述和基本使用...

柔光的暖阳◎ 2021-11-23 22:34 235阅读 0赞

新建类  
![87548-20190717155612056-676642126.png][]  
  
![87548-20190717155613098-1958148178.png][]  
多了个尖括号，大写字母E，这是什么意思呢？  
尖括号当中叫做泛型。存储的统一的类型，这个类型就在尖括号里面写上，我们用一个字母占位表示。  
![87548-20190717155610779-1782402852.png][]  
如何创建呢 构造方法有三个，最常用的就是无参构造  
![87548-20190717155612121-1124282240.png][]  
先掌握里面的add方法  
![87548-20190717155613074-485713927.png][]  
  
泛型只能是引用类型，不能是基本类型  
![87548-20190717155612570-365571102.png][]  
左边尖括号内必须写，右边可以写也可以不写  
![87548-20190717155612567-1629362298.png][]  
打印出来的不是一个地址  
![87548-20190717155613260-659699809.png][]  
  
![87548-20190717155611582-390891188.png][]  
写这个ArrayList的人对ArrayList进行了特殊处理  
  
![87548-20190717155612895-1438761536.png][]  
  
![87548-20190717155611522-502369250.png][]  
  
![87548-20190717155613230-1272842266.png][]  
往里面加数字就会报错  
![87548-20190717155612328-1965566379.png][]  
  
Ctrl+鼠标左键也可以进入到ArrayList的源码里面

![87548-20190717160952200-13187136.png][]

![87548-20190717160957478-1133891427.jpg][]

转载于:https://www.cnblogs.com/wangjunwei/p/11201495.html

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[87548-20190717155613230-1272842266.png]: /images/20211122/0f815b21e71d4e78810705efdb854b0d.png
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