how to replace element in list java?

The java.util.Collections class consists exclusively of static methods that operate on or return collections. It contains polymorphic algorithms that operate on collections, “wrappers”, which return a new collection backed by a specified collection, and a few other odds and ends.

Collections.fill() method will replaces all of the elements of the specified list with the specified element.
Syntax: public static void fill(List list, T obj)

Example

package com.w3schools;
 
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
 
public class Test { 
    public static void main(String a[]){         
        List<String> list = new ArrayList<String>();
        list.add("vikas");
        list.add("amit");
        list.add("anil");
        list.add("ajay");
        System.out.println("Original List: "+list);
        Collections.fill(list, "Temp_mahesh");
        System.out.println("After fill: "+list);
    }
}

Output

Original List: [vikas, amit, anil, ajay]
After fill: [Temp_mahesh, Temp_mahesh, Temp_mahesh, Temp_mahesh]

Java Collections class examples