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));    }} |
Output:
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));    }} |
Output:
Setting new value is successful = true Value of index 4 = CANADA
