Decrement by 1, return previous

Atomically decrements by one the current value and returns the previous value of the counter. It is possible that multiple concurrent client requests may receive the same previous value. This occurs since only the decrementing part of the logic is atomic, the retrieval of the value before it is decremented is not.

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

// Backendless.Counters approach
public Long Backendless.Counters.getAndDecrement( String counterName );

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

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

// Backendless.Counters approach
public <T> T Backendless.Counters.getAndDecrement( String counterName, 
                                                         AsyncCallback<T> callback );

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

where:

Argument	Description
counterName	name of the counter to decrement.
type	numeric type for the counter values. Can be an instance of Byte.class, Short.class, Integer.class, Float.class, Long.class and Double.class.
callback	the callback used for asynchronous calls to indicate that the operation has either successfully completed or resulted in error.

Example

AsyncCallback<Integer> callback = new AsyncCallback<Integer>()
{
  @Override
  public void handleResponse( Integer value )
  {
    Log.i( "MYAPP", "[ASYNC] previous counter value is - " + value );
  }

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

Backendless.Counters.getAndDecrement( "my counter", callback );

IAtomic<Integer> myCounter = Backendless.Counters.of( "my counter", Integer.class );
int counterValue = myCounter.getAndDecrement();
Log.i( "MYAPP", "[SYNC] previous counter value is - " + counterValue );