Replace an element in a Java ArrayList with set(index, element), which returns the old element. Find the index by value with indexOf(), replace all matches with Collections.replaceAll() or List.replaceAll(), and avoid IndexOutOfBoundsException.
Java ArrayList is part of the collection framework and implementation of resizable array data structure. Learn when to use array and arraylist.
Java ArrayList does not publicly expose the length of the backing array, and only the count of the stored elements can be retrieved using its size() method.
Learn to sort Java ArrayList in ascending and descending order using ArrayList.sort(), Collections.sort(), Comparator interface and Java 8 Streams.
Flattening a nested list may seem hard at the beginning, but it’s not. It can be easily done using only plain Java, streams, or external libraries.
Learn to create a List from array using Arrays.asList(array) and new ArrayList(Arrays.asList(array). Learn their differences with examples.
Java ArrayList class represents a resizable array of objects which allows us to add, remove, find, sort and replace elements.
Java CopyOnWriteArrayList is a thread-safe variant of ArrayList in which all mutative operations (add, set, and so on) are implemented by making a fresh copy of the underlying array. It’s immutable snapshot style iterator method uses a reference to the state of the array at the point that the iterator …
Learn to remove duplicate elements from an ArrayList using different techniques such as HashSet, LinkedHashSet, and using Java 8 stream.
Since Java 8, Spliterators are a special type of iterator that supports parallel iteration of portions of the source such as list, set, or array.
Java ArrayList.removeIf() removes all elements that satisfy a condition by iterating through the elements and matching against the specified Predicate.
ArrayList replaceAll() transform each element in the list by applying a lambda expression or UnaryOperator implementation.
In Java, the ArrayList.retainAll() retains only those elements in this list that are contained in the specified collection. Rest all elements are removed from the list. This method is exactly the opposite to removeAll() method. 1. Syntax The syntax to use the retainAll() method is: Method Argument – a collection …
ArrayList removeAll() removes all of matching elements that are contained in the specified method argument collection. It removes all occurrences of matching elements, not only first occurrence.
ArrayList remove() removes the first occurrence of the specified element from this list, if it is present, else the list remains unchanged.
Java ArrayList.listIterator() returns a bi-directional list iterator that iterates over the elements of the current list.
ArrayList forEach() method iterate the list and performs the argument action for each element of the list until all elements have been processed.
ArrayList.clone() creates a shallow copy of the given ArrayList. Learn to create deep copy and shallow copy of an arraylist with examples.
Java ArrayList.addAll() appends all of the elements of argument collection to the list at the end or the specified index position.
The ArrayList.add() in Java adds a single element to the list, either at the end of the list or at the specified index position. Always use generics for compile-time type safety while adding the element to the arraylist. 1. ArrayList.add() Method The add() method first ensures that there is sufficient …
Java LinkedList and ArrayList are different in many aspects, and we need to understand both to decide when to use which class.
In Java, ArrayList and Vector, both implement java.util.List interface and provide the capability to store and get objects within using simple API methods. Still, they are different in many aspects, and we need to understand both classes in detail to make a wise decision about when to use which class. …
Learn to convert a Set to List in Java using constructor, addAll() and Java 8 streams. Learn to convert list to set to remove duplicates.
Learn different and useful ways to convert array to list in Java. Learn to use Java 9 List, Java 8 Stream, Collections and Guava library.
Learn to convert LinkedList to ArrayList in Java with example. We will also learn to convert arraylist to linkedlist in Java.
Learn to convert ArrayList to an array using toArray() method. The toArray() returns an array containing all of the elements in the list.
ArrayList contains() method is used to check if the specified element exists in the given arraylist or not. If element exist then method returns true.
Learn to use ArrayList ensureCapacity() method to increase the capacity of already initialized arraylist to a desired size. It improve performance of list.
Learn to update or replace an existing element in ArrayList with a new specified element or value, using set (int index, Object newItem) method. 1. Replacing an Existing Item To replace an existing item, we must find the item’s exact position (index) in the ArrayList. Once we have the index, …
Learn to check if an ArrayList is empty using isEmpty() and size() methods. Note isEmpty() method internally checks the size of the list.
Learn to clear arraylist or empty an arraylist in Java. Clearing a list means to remove all elements from the list. Difference between clear and removeAll.
Learn how to merge two arraylists into a combined single arraylist in Java. Also learn to join arraylists without duplicates in the combined list.
Serialize an ArrayList to a file or a byte array with ObjectOutputStream, read it back with ObjectInputStream, handle the unchecked cast, and see when JSON with Jackson is the better choice.
Learn to swap two specified elements in ArrayList in Java. We will use Collections.swap() method to swap two elements within a specified arraylist at specified indices. 1. Collections.swap() API The Collections.swap() method swaps the elements at the specified positions in the specified list. The index arguments must be a valid …
Learn to synchronize an ArrayList using either Collections.synchronizedList() or CopyOnWriteArrayList class with examples.
Learn to compare two arraylists in Java with List Items. Learn to test whether two arraylists are equal and then find different list items.
Learn how to get the element from an ArrayList. We will be using ArrayList.get() method to get the object at the specified index of the arraylist.
Learn to get the index of the first occurrence of an element in an arraylist in Java using ArrayList.indexOf() method with a simple example.
Learn to get the index of last occurrence of an element in the arraylist in Java using Arraylist.lastIndexOf() method with a simple example.
Learn to get a sublist from an existing ArrayList using ArrayList.subList() and modify the original list using the sublist view.
The Java ArrayList class is part of the Collection framework and is an implementation of a resizable array data structure. It automatically grows and shrinks when elements are added or removed in the runtime, whenever required, This Java tutorial discussed the different ways to add multiple items to an ArrayList …
Learn to remove element from ArrayList. Remove element at specifed index, or element value. Remove all elements from arraylist for spcified value example.
Java programs to add single or multiple elements at the specified index of arraylist with ArrayList.add() and addAll() methods.
The Java iterate through ArrayList programs. Learn how to retrieve values from ArrayList in Java using for loop, while loop, iterator and stream api.
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