Java删除ArrayList中的重复对象
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Java remove duplicate objects in ArrayList
提问by eggHunter
I have a very lengthy ArrayList comprised of objects some of them however, are undoubtedly duplicates. What is the best way of finding and removing these duplicates. Note: I have written a boolean-returning compareObjects() method.
我有一个很长的 ArrayList 由对象组成，但其中一些对象无疑是重复的。查找和删除这些重复项的最佳方法是什么。注意：我编写了一个返回布尔值的 compareObjects() 方法。
回答by ashes999
You mentioned writing a compareObjectsmethod. Actually, you should override the equalsmethod to return truewhen two objects are equal.
你提到写一个compareObjects方法。实际上，当两个对象相等时，您应该覆盖该equals方法以返回true。
Having said that, I would just return a new list that contains unique elements from the original:
话虽如此，我只想返回一个包含原始元素的新列表：
ArrayList<T> original = ...
List<T> uniques = new ArrayList<T>();
for (T element : original) {
if (!uniques.contains(element)) {
uniques.add(element);
}
}
This only works if you override equals. See this questionfor more information.
这仅在您覆盖equals. 有关更多信息，请参阅此问题。
回答by e.doroskevic
Example
例子
List<Item> result = new ArrayList<Item>();
Set<String> titles = new HashSet<String>();
for( Item item : originalList ) {
if( titles.add( item.getTitle() ) {
result.add( item );
}
}
Reference
参考
回答by Nana Ghartey
Hashsetwill remove duplicates. Example:
Hashset将删除重复项。例子：
Set< String > uniqueItems = new HashSet< String >();
uniqueItems.add("a");
uniqueItems.add("a");
uniqueItems.add("b");
uniqueItems.add("c");
The set "uniqueItems" will contain the following : a, b, c
集合“uniqueItems”将包含以下内容：a、b、c
