<span class="keyword" style="background-color: rgb(250, 250, 250); font-size: 1em; font-family: Monaco, 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', Consolas, 'Courier New', monospace;">boolean</span><span style="color: black; background-color: rgb(250, 250, 250); font-size: 1em; font-family: Monaco, 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', Consolas, 'Courier New', monospace;">retainAll(Collection<?>c);</span>

在网上查到了 retainAll方法

然后就在代码中添加

<pre name="code" class="html">List<Employee> <span style="font-family: Arial, Helvetica, sans-serif;">employeeOfIntermediarys </span><span style="font-family: Arial, Helvetica, sans-serif;">= new ArrayList<Employee>();</span><pre name="code" class="html">List<Employee> <span style="font-family: Arial, Helvetica, sans-serif;">tempList </span><span style="font-family: Arial, Helvetica, sans-serif;">= new ArrayList<Employee>();</span>if(tempList != null){<span style="white-space:pre"> </span>//去掉<span style="font-family: Arial, Helvetica, sans-serif;">tempList 中与</span><span style="font-family: Arial, Helvetica, sans-serif;">employeeOfIntermediarys 中</span>相同的元素，在合并 List<Employee> eoiList = new ArrayList<Employee>(employeeOfIntermediarys); if (eoiList.retainAll(tempList)) { tempList.removeAll(eoiList); } employeeOfIntermediarys.addAll(tempList);}

然后发现不可以，查了好多东西，发现代码是对的，只是需要重写equals方法。

不知道为什么，因为之前写的小demo中用自定义的类book，如下，是可以正常使用的

public class Book { private int id; private String nameString; private String writer; public Book(){ id= -1; nameString = ""; writer = ""; }List<Book> books = new ArrayList<Book>(); List<Book> tempList = new ArrayList<Book>(); Book book1 = new Book(); book1.setId(1); book1.setNameString("dkjdf"); Book book2 = new Book(); book2.setId(2); book2.setNameString("到加福禄寿"); Book book3 = new Book(); book3.setId(3); book3.setNameString("dj地方"); Book book4 = new Book(); book4.setId(4); book4.setNameString("dkjdf"); Book book5 = new Book(); book5.setId(5); book5.setNameString("到加福禄寿"); Book book6 = new Book(); book6.setId(6); book6.setNameString("dj地方"); books.add(book1); books.add(book2); books.add(book5); books.add(null); tempList.add(book1); tempList.add(book4); tempList.add(null); tempList.retainAll(books); System.out.println(tempList.get(0).booktoString());

whatever，准备找一找collection的源代码看看，

重写了Employee中的equals方法后 。

如下：

@Override public boolean equals(Object c){ if (!(c instanceof Employee)) { return false; } Employee eoi = (Employee) c; if (eoi.getUserGuid().equals(userGuid)) { return true; } return false; }

上面的代码就可以正常运行了。

以上就是小编为大家带来的去除arraylist容器中的相同的对象元素的方法的全部内容了，希望对大家有所帮助，多多支持~