I have an ArrayList
in Java
:
{"deleteItem", "createitem", "exportitem", "deleteItems", "createItems"}
I want to move all string which contains delete
to the end of the list, so I would get the next:
{"createitem", "exportitem", "createItems", "deleteItem", "deleteItems"}`
I can create two sublists - one for the words which contain the 'delete' word, and one for the others, and then merge them, but I search for a more efficient way.
Method #1 : Using append() + pop() + index() This particular functionality can be performed in one line by combining these functions. The append function adds the element removed by pop function using the index provided by index function.
Use the del statement with list slicing to remove the last N elements from a list, e.g. del my_list[len(my_list) - n:] The del statement will remove the last N elements from the original list.
Use custom Comparator:
List<String> strings = Arrays.asList(
"deleteItem", "createitem", "exportitem", "deleteItems", "createItems"
);
Comparator<String> comparator = new Comparator<String>() {
@Override
public int compare(final String o1, final String o2) {
if (o1.contains("delete") && !o2.contains("delete")) {
return 1;
}else if (!o1.contains("delete") && o2.contains("delete")) {
return -1;
}
return 0;
}
};
Collections.sort(strings, comparator);
System.out.println(strings);
If you want something efficient and need to remove elements in the beginning and middle of a List
I would suggest using a LinkedList
instead of a array list. That would avoid rewriting the underlying array for each remove operation.
Then, you simply iterate on the list, calling remove
and addLast
for any string that contains delete
.
Of course, this is only OK if there is nothing preventing you from replacing your ArrayList
with a LinkedList
.
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