Java Collections fill() Method

The fill() method of Java Collections class is used to replace all of the elements of the specified list with the specified elements. This method filled all the elements with the same values.

Syntax

Following is the declaration of fill() method:

Parameter

Parameter	Description	Required/Optional
list	It is the list to be filled with the specified elements.	Required
obj	It is the element to fill the specified list.	Required

Returns

The fill() method does not return anything.

Exceptions

UnsupportedOperationException- This exception will be thrown if the specified list or its list-iterator does not support the set operation.

Compatibility Version

Java 1.4 and above

Example 1

import java.util.*;
public class CollectionsFillExample1 {
	public static void main(String[] args) {
	    //Create a list object       
	    List<String> arrlist = new ArrayList<String>();
	    //Add elements in the list
	    arrlist.add("AAA");
	    arrlist.add("BBB");
	    arrlist.add("CCC");
	    System.out.println("List elements before Replacements: "+arrlist);
	    //Fill the list with 'JavaTpoint'
	    Collections.fill(arrlist,"JavaTpoint");
	    System.out.println("List elements after Replacements: "+arrlist);
	    }	  
}

Test it Now

Output:

List elements before Replacements: [AAA, BBB, CCC]
List elements after Replacements: [JavaTpoint, JavaTpoint, JavaTpoint]

Example 2

import java.util.*;
public class CollectionsFillExample2 {
	public static void main(String[] args) {
		//Create a list object       	    
	      List<Integer> arrList = Arrays.asList(1,2,3,4);	   
	      //Fill the list with 551
		Collections.fill(arrList,551);
	      //Print the List
	      for(Integer i :arrList) {
		      System.out.print(i +" ");
                  }
	      }	  
}

Test it Now

Output:

551 551 551 551

Example 3

import java.util.*;
public class CollectionsFillExample3 {
	public static void main(String[] args) {
		List<String> list = new ArrayList<>();
	      for (int i = 0; i < 6; i++)
	      list.add("Hi");	    
	      System.out.println("Before Fill: "+list);
	      Collections.fill(list, "Hello");
	      System.out.println("After Fill: "+list);
	      }	  
}

Test it Now

Output:

Before Fill: [Hi, Hi, Hi, Hi, Hi, Hi]
After Fill: [Hello, Hello, Hello, Hello, Hello, Hello]

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Java Collections fill() Method

Syntax

Parameter

Returns

Exceptions

Compatibility Version

Example 1

Example 2

Example 3