Java ArrayList, Java ArrayList Tutorial

Java ArrayList Tutorial

Java ArrayList is a resizable array which implements List interface. ArrayList provides all operation defined by List interface. Internally ArrayList uses array to store elements. ArrayList provides addition methods to manipulate this array that actually stores the elements.

ArrayList is equivalent to Vector, but ArrayList is not synchronized.

Java ArrayList Capacity

Capacity of the Java ArrayList is the actual size of the array used to store the list elements. Capacity of the ArrayList grows automatically as we add elements to it. Every time this happens the internal array has to be reallocated. This increases the load. We can set increase the capacity of the ArrayList using following method.

ArrayList arrayList = new ArrayList();
arrayList.ensureCapacity(100);


Java ArrayList Iterators

Java ArrayList provides two types of Iterators.
1) Iterator
2) ListIterator

Using following methods.

Iterator iterator = arrayList.iterator();
Returns Iterator object.

ListIterator listIterator = arrayList.listIterator();
Returns Object of ListIterator.

ListIterator listIterator = arrayList.listIterator(int startIndex);
Returns object of ListIterator. The first next method call on this ListIterator object will return the element at the specified index passed to get the ListIterator object.

Iterators returned by these methods are fail-fast. That means if the list is modified after getting the Iterator by using some other means rather than Iterators own add or remove method, Iterator will throw ConcurrentModificationException.


Java ArrayList Constructors >>

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