CopyOnWriteArrayList addIfAbsent() method in Java
Last Updated :
26 Nov, 2018
The addIfAbsent(E e) method of CopyOnWriteArrayList appends the element passed in the parameter to the end of the List if the element is not present in the list. The function returns true on addition of new element to the list.
Syntax:
public boolean addIfAbsent(E e)
Parameters: The function accepts a single mandatory parameter element which specifies the element to be appended to the list if it is not present.
Return Value: The function returns true if it is added to the list.
Below programs illustrate the above function:
Program 1:
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
CopyOnWriteArrayList<Integer> ArrLis
= new CopyOnWriteArrayList<Integer>();
ArrLis.addIfAbsent( 2 );
ArrLis.addIfAbsent( 3 );
ArrLis.addIfAbsent( 4 );
ArrLis.addIfAbsent( 7 );
System.out.println( "CopyOnWriteArrayList: "
+ ArrLis);
System.out.println( "On adding 4 it returns "
+ ArrLis.addIfAbsent( 4 ) + " as it is present" );
}
}
|
Output:
CopyOnWriteArrayList: [2, 3, 4, 7]
On adding 4 it returns false as it is present
Program 2:
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
CopyOnWriteArrayList<String> ArrLis
= new CopyOnWriteArrayList<String>();
ArrLis.addIfAbsent( "gopal" );
ArrLis.addIfAbsent( "gfg" );
ArrLis.addIfAbsent( "jgec" );
ArrLis.addIfAbsent( "sudo" );
System.out.println( "CopyOnWriteArrayList: " + ArrLis);
System.out.println( "On adding 'sudo' it returns "
+ ArrLis.addIfAbsent( "sudo" ) + " as it is present" );
}
}
|
Output:
CopyOnWriteArrayList: [gopal, gfg, jgec, sudo]
On adding 'sudo' it returns false as it is present
Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CopyOnWriteArrayList.html#addIfAbsent-E-
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