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Replace specific element of List example

This is an example of how to replace a specific element of a List. We will use the replaceAll(List list, Object oldVal, Object newVal) API method of the Collections class. The ArrayList is used as a List implementation, but the same API applies to any type of List implementation classes e.g. Vector etc. Replacing a specific element of a List implies that you should:

  • Create a new ArrayList.
  • Populate the list with elements, with the add(E e) API method of the ArrayList.
  • Invoke the replaceAll(List list, Object oldVal, Object newVal) API method of the Collections. It will replace all occurrences of the specified element from the list with the new provided element. The method will return true if at least one replacement has occurred.

Let’s take a look at the code snippet that follows:

package com.javacodegeeks.snippets.core;
 
import java.util.ArrayList;
import java.util.Collections;
 
public class ReplaceElementOfList {
 
  public static void main(String[] args) {

    /*

Please note that the same API applies to any type of 

List implementation classes e.g. Vector etc

*/

    // Create an ArrayList and populate it with elements
    ArrayList arrayList = new ArrayList();
    arrayList.add("element_1");
    arrayList.add("element_2");
    arrayList.add("element_3"); 
    arrayList.add("element_4"); 
    arrayList.add("element_5"); 

    System.out.println("ArrayList elements : " + arrayList);

    /*

static boolean replaceAll(List list, Object oldVal, Object newVal) operation 

replaces all occurrences of the specified element from the provided List with 

the new provided element. The method returns true if at least one replacement 

occurred
    */
    Collections.replaceAll(arrayList, "element_3","element_6");
 
    System.out.println("ArrayList elements after replacement with element_3 : " + arrayList);
 
  }
}

Output:

ArrayList elements : [element_1, element_2, element_3, element_4, element_5]
ArrayList elements after replacement with element_3 : [element_1, element_2, element_6, element_4, element_5]

 
This was an example of how to replace a specific element of a List in Java.

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