public Device getDevice ( String id ) throws UnknownDeviceException , NullIdException { if ( ( id == null ) || ( id . trim ( ) . equals ( "" ) ) ) { throw new NullIdException ( ) ; } else { if ( this . devices . containsKey ( id ) ) { return this . devices . get ( id ) ; } else { throw new UnknownDeviceException ( ) ; } } }
Get a device according to his id