list.set java

The java.util.ArrayList.set[int index, E element] replaces the element at the specified position in this list with the specified element.

Declaration

Following is the declaration for java.util.ArrayList.set[] method

public E set[int index, E element]

Parameters

• index − This is the index of the element to replace.

• element − This is the element to be stored at the specified position.

Return Value

This method returns the element previously at the specified position.

Exception

IndexOutOfBoundsException − If the index is out of range

Example

The following example shows the usage of java.util.Arraylist.set[] method.

package com.tutorialspoint; import java.util.ArrayList; public class ArrayListDemo { public static void main[String[] args] { // create an empty arraylist with an initial capacity ArrayList arrlist = new ArrayList[5]; // use add[] method to add elements in the list arrlist.add[15]; arrlist.add[20]; arrlist.add[25]; arrlist.add[22]; // let us print all the elements available in list for [Integer number : arrlist] { System.out.println["Number = " + number]; } // inserting elment 55 at 3rd position arrlist.set[2,55]; // let us print all the elements available in list System.out.println["Printing new list:"]; for [Integer number : arrlist] { System.out.println["Number = " + number]; } } }

Let us compile and run the above program, this will produce the following result −

Number = 15 Number = 20 Number = 25 Number = 22 Printing new list: Number = 15 Number = 20 Number = 55 Number = 22

java_util_arraylist.htm

We're sorry, but the page you were looking for doesn't exist.

Here are some useful links

The syntax of the set[] method is:

arraylist.set[int index, E element]

Here, arraylist is an object of the ArrayList class.

set[] Parameters

The set[] method takes two parameters.

• index - position of the element to be replaced
• element - new element that is to be stored at index

set[] Return Values

• returns the element previously present at index
• throws IndexOutOfBoundsException, if index is out of range

Example 1: Replace an Element in ArrayList

import java.util.ArrayList; class Main { public static void main[String[] args] { // create an ArrayList ArrayList languages = new ArrayList[]; // add elements to ArrayList languages.add["Python"]; languages.add["English"]; languages.add["JavaScript"]; System.out.println["ArrayList: " + languages]; // replace element at index 1 String element = languages.set[1, "Java"]; System.out.println["Updated ArrayList: " + languages]; System.out.println["Replaced Element: " + element]; } }

Output

ArrayList: [Python, English, JavaScript] Updated ArrayList: [Python, Java, JavaScript] Replaced Element: English

In the above example, we have created an arraylist named languages. Here, we have used the set[] method to replace the element at index 1 [English] with Java.

Note: If you are not sure about the index number of an element, you can use the ArrayList indexOf[] method.

ArrayList set[] Vs. add[]

The syntax of the add[] and set[] method looks quite similar.

// syntax of add[] arraylist.add[int index, E element] // syntax of set[] arraylist.set[int index, E element]

And, both the methods are adding a new element to the arraylist. This is why some people consider both methods similar.

However, there is a major difference between them.

• The set[] method adds a new element at the specified position by replacing the older element at that position.
• The add[] method adds a new element at the specified position by shifting the older element towards the right position.

Example 2: ArrayList set[] Vs. add[]

import java.util.ArrayList; class Main { public static void main[String[] args] { // create an ArrayList ArrayList languages1 = new ArrayList[]; // add elements to ArrayList languages1.add["Python"]; languages1.add["English"]; languages1.add["JavaScript"]; // create another ArrayList similar to languages1 ArrayList languages2 = new ArrayList[]; // adds all elements from languages1 to languages2 languages2.addAll[languages1]; System.out.println["ArrayList: " + languages1]; // use of set[] languages1.set[1, "Java"]; System.out.println["ArrayList after set[]: " + languages1]; // use of add[] languages2.add[1, "Java"]; System.out.println["ArrayList after add[]: " + languages2]; } }

Output

ArrayList: [Python, English, JavaScript] ArrayList after set[]: [Python, Java, JavaScript] ArrayList after add[]: [Python, Java, English, JavaScript]

In the above example, we have created two arraylists named languages1 and languages2. We have used the ArrayList addAll[] method so that both arraylists have the same elements.

Here,

• the set[] method replaces the element English at position 1
• the add[] method shifts the element English to position 2

To learn more about adding value, visit Java ArrayList add[].

• Type Parameters: E - the type of elements in this list All Superinterfaces: Collection, Iterable All Known Implementing Classes: AbstractList, AbstractSequentialList, ArrayList, AttributeList, CopyOnWriteArrayList, LinkedList, RoleList, RoleUnresolvedList, Stack, Vector
  public interface List extends Collection

  An ordered collection [also known as a sequence]. The user of this interface has precise control over where in the list each element is inserted. The user can access elements by their integer index [position in the list], and search for elements in the list.

  Unlike sets, lists typically allow duplicate elements. More formally, lists typically allow pairs of elements e1 and e2 such that e1.equals[e2], and they typically allow multiple null elements if they allow null elements at all. It is not inconceivable that someone might wish to implement a list that prohibits duplicates, by throwing runtime exceptions when the user attempts to insert them, but we expect this usage to be rare.

  The List interface places additional stipulations, beyond those specified in the Collection interface, on the contracts of the iterator, add, remove, equals, and hashCode methods. Declarations for other inherited methods are also included here for convenience.

  The List interface provides four methods for positional [indexed] access to list elements. Lists [like Java arrays] are zero based. Note that these operations may execute in time proportional to the index value for some implementations [the LinkedList class, for example]. Thus, iterating over the elements in a list is typically preferable to indexing through it if the caller does not know the implementation.

  The List interface provides a special iterator, called a ListIterator, that allows element insertion and replacement, and bidirectional access in addition to the normal operations that the Iterator interface provides. A method is provided to obtain a list iterator that starts at a specified position in the list.

  The List interface provides two methods to search for a specified object. From a performance standpoint, these methods should be used with caution. In many implementations they will perform costly linear searches.

  The List interface provides two methods to efficiently insert and remove multiple elements at an arbitrary point in the list.

  Note: While it is permissible for lists to contain themselves as elements, extreme caution is advised: the equals and hashCode methods are no longer well defined on such a list.

  Some list implementations have restrictions on the elements that they may contain. For example, some implementations prohibit null elements, and some have restrictions on the types of their elements. Attempting to add an ineligible element throws an unchecked exception, typically NullPointerException or ClassCastException. Attempting to query the presence of an ineligible element may throw an exception, or it may simply return false; some implementations will exhibit the former behavior and some will exhibit the latter. More generally, attempting an operation on an ineligible element whose completion would not result in the insertion of an ineligible element into the list may throw an exception or it may succeed, at the option of the implementation. Such exceptions are marked as "optional" in the specification for this interface.

  This interface is a member of the Java Collections Framework.

  Since: 1.2 See Also: Collection, Set, ArrayList, LinkedList, Vector, Arrays.asList[Object[]], Collections.nCopies[int, Object], Collections.EMPTY_LIST, AbstractList, AbstractSequentialList

• • • parallelStream, removeIf, stream

• • • int size[]

      Returns the number of elements in this list. If this list contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

      Specified by: size in interface Collection Returns: the number of elements in this list
    • boolean isEmpty[]

      Returns true if this list contains no elements.

      Specified by: isEmpty in interface Collection Returns: true if this list contains no elements
    • boolean contains[Object o]

      Returns true if this list contains the specified element. More formally, returns true if and only if this list contains at least one element e such that [o==null ? e==null : o.equals[e]].

      Specified by: contains in interface Collection Parameters: o - element whose presence in this list is to be tested Returns: true if this list contains the specified element Throws: ClassCastException - if the type of the specified element is incompatible with this list [optional] NullPointerException - if the specified element is null and this list does not permit null elements [optional]
    • Iterator iterator[]

      Returns an iterator over the elements in this list in proper sequence.

      Specified by: iterator in interface Collection Specified by: iterator in interface Iterable Returns: an iterator over the elements in this list in proper sequence
    • Object[] toArray[]

      Returns an array containing all of the elements in this list in proper sequence [from first to last element].

      The returned array will be "safe" in that no references to it are maintained by this list. [In other words, this method must allocate a new array even if this list is backed by an array]. The caller is thus free to modify the returned array.

      This method acts as bridge between array-based and collection-based APIs.

      Specified by: toArray in interface Collection Returns: an array containing all of the elements in this list in proper sequence See Also: Arrays.asList[Object[]]
    •  T[] toArray[T[] a]

      Returns an array containing all of the elements in this list in proper sequence [from first to last element]; the runtime type of the returned array is that of the specified array. If the list fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this list.

      If the list fits in the specified array with room to spare [i.e., the array has more elements than the list], the element in the array immediately following the end of the list is set to null. [This is useful in determining the length of the list only if the caller knows that the list does not contain any null elements.]

      Like the toArray[] method, this method acts as bridge between array-based and collection-based APIs. Further, this method allows precise control over the runtime type of the output array, and may, under certain circumstances, be used to save allocation costs.

      Suppose x is a list known to contain only strings. The following code can be used to dump the list into a newly allocated array of String:

      String[] y = x.toArray[new String[0]]; Note that toArray[new Object[0]] is identical in function to toArray[].
      Specified by: toArray in interface Collection Type Parameters: T - the runtime type of the array to contain the collection Parameters: a - the array into which the elements of this list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose. Returns: an array containing the elements of this list Throws: ArrayStoreException - if the runtime type of the specified array is not a supertype of the runtime type of every element in this list NullPointerException - if the specified array is null
    • boolean add[E e]

      Appends the specified element to the end of this list [optional operation].

      Lists that support this operation may place limitations on what elements may be added to this list. In particular, some lists will refuse to add null elements, and others will impose restrictions on the type of elements that may be added. List classes should clearly specify in their documentation any restrictions on what elements may be added.

      Specified by: add in interface Collection Parameters: e - element to be appended to this list Returns: true [as specified by Collection.add[E]] Throws: UnsupportedOperationException - if the add operation is not supported by this list ClassCastException - if the class of the specified element prevents it from being added to this list NullPointerException - if the specified element is null and this list does not permit null elements IllegalArgumentException - if some property of this element prevents it from being added to this list
    • boolean remove[Object o]

      Removes the first occurrence of the specified element from this list, if it is present [optional operation]. If this list does not contain the element, it is unchanged. More formally, removes the element with the lowest index i such that [o==null ? get[i]==null : o.equals[get[i]]] [if such an element exists]. Returns true if this list contained the specified element [or equivalently, if this list changed as a result of the call].

      Specified by: remove in interface Collection Parameters: o - element to be removed from this list, if present Returns: true if this list contained the specified element Throws: ClassCastException - if the type of the specified element is incompatible with this list [optional] NullPointerException - if the specified element is null and this list does not permit null elements [optional] UnsupportedOperationException - if the remove operation is not supported by this list
    • boolean containsAll[Collection c]

      Returns true if this list contains all of the elements of the specified collection.

      Specified by: containsAll in interface Collection Parameters: c - collection to be checked for containment in this list Returns: true if this list contains all of the elements of the specified collection Throws: ClassCastException - if the types of one or more elements in the specified collection are incompatible with this list [optional] NullPointerException - if the specified collection contains one or more null elements and this list does not permit null elements [optional], or if the specified collection is null See Also: contains[Object]
    • boolean addAll[Collection