The weakCompareAndSet() method of a AtomicReferenceArray class is used to atomically sets the value of the element at index i to newValue to newValue for AtomicReferenceArray if the current value is equal to expectedValue passed as parameter. This method updates the value at index i with memory semantics of reading as if the variable was declared volatile type of variable. This method returns true if set a new value to AtomicReference is successful.
Syntax:
public final boolean weakCompareAndSet( int i, E expectedValue, E newValue)
Parameters: This method accepts:
- i which is an index of AtomicReferenceArray to perform the operation,
- expectedValue which is the expected value and
- newValue which is the new value to set.
Return value: This method returns true if set a new value to AtomicReference is successful.
Below programs illustrate the weakCompareAndSet() method:
Program 1:
// Java program to demonstrate // weakCompareAndSet() method import java.util.concurrent.atomic.*;
public class GFG {
public static void main(String[] args)
{
// create an atomic reference object.
AtomicReferenceArray<Integer> ref
= new AtomicReferenceArray<Integer>( 5 );
// set some value
ref.set( 0 , 543 );
ref.set( 1 , 124 );
ref.set( 2 , 322 );
// apply weakCompareAndSet()
boolean result
= ref.weakCompareAndSet( 0 , 124 ,
234 );
// print value
System.out.println( "Setting new value"
+ " is successful = "
+ result);
System.out.println( "Value of index 0 = "
+ ref.get( 0 ));
}
} |
Setting new value is successful = false Value of index 0 = 543
Program 2:
// Java program to demonstrate // weakCompareAndSet() method import java.util.concurrent.atomic.*;
public class GFG {
public static void main(String[] args)
{
// create an atomic reference object.c
AtomicReferenceArray<String> ref
= new AtomicReferenceArray<String>( 5 );
// set some value
ref.set( 0 , "INDIA" );
ref.set( 1 , "US" );
ref.set( 2 , "UK" );
ref.set( 3 , "CHINA" );
ref.set( 4 , "CHINA" );
// apply weakCompareAndSet()
boolean result
= ref.weakCompareAndSet( 4 , "CHINA" ,
"CANADA" );
// print value
System.out.println( "Setting new value"
+ " is successful = "
+ result);
System.out.println( "Value of index 4 = "
+ ref.get( 4 ));
}
} |
Setting new value is successful = true Value of index 4 = CANADA