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
