question: @ Override public boolean equals ( Object obj ) { if ( ! ( obj instanceof Position ) ) { return false ; } if ( obj == this ) { return true ; } Position position = ( Position ) obj ; if ( position . getLatitude ( ) != latitude ) { return false ; } else if ( position . getLongitude ( ) != longitude ) { return false ; } else if ( Double . isNaN ( position . getAltitude ( ) ) != Double . isNaN ( altitude ) ) { return false ; } else if ( ! Double . isNaN ( altitude ) && position . getAltitude ( ) != altitude ) { return false ; } return true ; }
target:  Indicates whether some other object is "equal to" this one.