Java Utility Library

Java Collections - replaceAll() Method

The java.util.Collections.replaceAll() method is used to replace all occurrences of one specified value in a list with another.

Syntax

public static <T> boolean replaceAll(List<T> list,
                                     T oldVal,
                                     T newVal)

Here, T is the type of element in the list.

Parameters

`list`	Specify the list in which replacement is to occur.
`oldVal`	Specify the old value to be replaced.
`newVal`	Specify the new value with which oldVal is to be replaced.

Return Value

Returns true if list contained one or more elements e such that (oldVal==null ? e==null : oldVal.equals(e)).

Exception

Throws UnsupportedOperationException, if the specified list or its list-iterator does not support the set operation.

Example:

In the example below, the java.util.Collections.replaceAll() method is used to replace all occurrences of specified element with new element in the given list.

import java.util.*;

public class MyClass {
  public static void main(String[] args) {
    //creating a list objects
    List<Integer> MyList = new ArrayList<Integer>();

    //populating MyList
    MyList.add(10);
    MyList.add(20);
    MyList.add(30);
    MyList.add(10);
    MyList.add(10);
    MyList.add(10);
    MyList.add(60);

    //printing the MyList
    System.out.println("MyList contains: " + MyList); 

    //replacing all occurrences of 10 with 25
    Collections.replaceAll(MyList, 10, 25);

    //printing the MyList
    System.out.println("MyList contains: " + MyList); 
  }
}

The output of the above code will be:

MyList contains: [10, 20, 30, 10, 10, 10, 60]
MyList contains: [25, 20, 30, 25, 25, 25, 60]

❮ Java.util - Collections