Conditional update

Atomically sets the value to the given updated value if the current value == the expected value.

// *******************************************
// synchronous methods
// *******************************************

// Backendless.Counters approach
public Long Backendless.Counters.compareAndSet( String counterName, 
                                                Number expected, 
                                                Number updated );

// IAtomic approach
IAtomic<T> counter = Backendless.Counters.of( String counterName, 
                                                    Class<? extends T> type );
public T counter.compareAndSet( Number expected, Number updated );

// *******************************************
// asynchronous methods
// *******************************************

// Backendless.Counters approach
public <T> T Backendless.Counters.compareAndSet( String counterName, 
                                                       Number expected, 
                                                       Number updated, 
                                                       AsyncCallback<T> callback );

// IAtomic approach
IAtomic<T> counter = Backendless.Counters.of( String counterName, 
                                                    Class<? extends T> type );
public T counter.compareAndSet( Number expected, 
                                Number updated, 
                                AsyncCallback<T> callback );

where:

Argument	Description
counterName	name of the counter to compare.
expected	the expected value of the counter. If the current value equals the expected value, the counter is set to the "updated" value.
updated	the new value to assign to the counter if the current value equals the expected value.
callback	the callback used for asynchronous calls to indicate that the operation has either successfully completed or resulted in error.

Example

AsyncCallback<Boolean> callback = new AsyncCallback<Boolean>()
{
  @Override
  public void handleResponse( Boolean result )
  {
    Log.i( "MYAPP", "[ASYNC] value has been updated - " + result );
  }

  @Override
  public void handleFault( BackendlessFault backendlessFault )
  {
    Log.e( "MYAPP", "Error - " + backendlessFault.getMessage() );
  }
};

Backendless.Counters.compareAndSet( "my counter", 1000, 2000, callback );

IAtomic<Integer> myCounter = Backendless.Counters.of( "my counter", Integer.class );
boolean result = myCounter.compareAndSet( 1000, 2000 );
Log.i( "MYAPP", "[SYNC] value has been updated - " + result );

Codeless Reference

where:

Argument	Description
counter name	Name of the counter whose value must be set.
expected value	This property sets the following condition: If the expected value equals to the current value of the counter, then the operation sets a new number for the counter. Otherwise, the operation does not set the new value for the counter.
new value	Specify the new number for the counter.
return current value	When this box is checked, the operation returns the current value of the counter.

Returns the current value of the counter.

Consider the following counter:

The example below checks if the expected value of the "CarsParkingLot" counter equals to 20, and if it does equal to 20, then the operation sets a new value to 35.

The result of this operation will look as shown below after the Codeless logic runs: