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How can I get the last value of an ArrayList?
I don't know the last index of the ArrayList.
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Approach: Get the ArrayList with elements. Get the first element of ArrayList with use of get(index) method by passing index = 0. Get the last element of ArrayList with use of get(index) method by passing index = size – 1.
Any element in list can be accessed using zero based index. If index is a negative number, count of index starts from end. As we want last element in list, use -1 as index.
The lastIndexOf() method of ArrayList in Java is used to get the index of the last occurrence of an element in an ArrayList object. Parameter : The element whose last index is to be returned. Returns : It returns the last occurrence of the element passed in the parameter.
To get the first element of a ArrayList, we can use the list. get() method by passing 0 as an argument. 0 is refers to first element index.
The following is part of the List interface (which ArrayList implements):
E e = list.get(list.size() - 1); E is the element type. If the list is empty, get throws an IndexOutOfBoundsException. You can find the whole API documentation here.
62
There isn't an elegant way in vanilla Java.
The Google Guava library is great - check out their Iterables class. This method will throw a NoSuchElementException if the list is empty, as opposed to an IndexOutOfBoundsException, as with the typical size()-1 approach - I find a NoSuchElementException much nicer, or the ability to specify a default:
lastElement = Iterables.getLast(iterableList); You can also provide a default value if the list is empty, instead of an exception:
lastElement = Iterables.getLast(iterableList, null); or, if you're using Options:
lastElementRaw = Iterables.getLast(iterableList, null); lastElement = (lastElementRaw == null) ? Option.none() : Option.some(lastElementRaw); If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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