java.util.Collections.copy() Method

Description

The copy(List<? super T>, List<? extends T>) method is used to copy all of the elements from one list into another.

Declaration

Following is the declaration for java.util.Collections.copy() method.

public static <T> void copy(List<? super T> dest,List<? extends T> src)

Parameters

• dest--This is the destination list.

• src--This is the source list.

Return Value

NA

Exception

• IndexOutOfBoundsException--This is thrown if the destination list is too small to contain the entire source List.

• UnsupportedOperationException--This is thrown if the destination list's list-iterator does not support the set operation.

Example

The following example shows the usage of java.util.Collections.copy()

package com.tutorialspoint;

import java.util.*;

public class CollectionsDemo {
   public static void main(String args[]) {
      // create two lists    
      List<String> srclst = new ArrayList<String>(5);
      List<String> destlst = new ArrayList<String>(10);
      
      // populate two lists
      srclst.add("Java");
      srclst.add("is");
      srclst.add("best");
      
      destlst.add("C++");
      destlst.add("is");
      destlst.add("older");
      
      
      // copy into dest list
      Collections.copy(destlst, srclst);            
      
      System.out.println("Value of source list: "+srclst);
      System.out.println("Value of destination list: "+destlst);
   }    
}

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

Value of source list: [Java, is, best]
Value of destination list: [Java, is, best]