How to find the index position of an item in a list when it contains true

Question

I have a List from HashMap , so I use List.contains to find out if the list contains the specified HashMap . In case this is the case, I want to extract this element from the list, so How do I know the position of the index, where is the element?

  List benefit = new ArrayList(); HashMap map = new HashMap(); map.put("one", "1"); benefit.add(map); HashMap map4 = new HashMap(); map4.put("one", "1"); System.out.println("size: " + benefit.size()); System.out.println("does it contain orig: " + benefit.contains(map)); System.out.println("does it contain new: " + benefit.contains(map4)); if (benefit.contains(map4)) //how to get index position where map4 was found in benefit list? 

Answer 1

What happened with:

 benefit.indexOf(map4) 

? It either returns an index, or -1 if no elements are found.

BTW I strongly recommend wrapping the card in an object and, if possible, using generics.

Answer 2

indexOf(object)

get(index)

Answer 3

Use List.indexOf() . This will give you the first match if there are multiple duplicates.

Answer 4

List # indexOf

Answer 5

Here is an example:

 List<String> names; names.add("toto"); names.add("Lala"); names.add("papa"); int index = names.indexOf("papa"); // index = 2 

Answer 6

int indexOf(Object o) This method returns the index in this list of the first occurrence of the specified element, or -1 if this list does not contain this element.