Hello, i’ve found these notes (tipps) for SCJA, but I have difficulties in interpreting them: Can someone give code examples or say in few words, what exactly stand behind these notes?
* declarative user interface construction – is NOT part of the J2EE specification.
what does it mean: declarative user interface construction? Maybe an example is helpful.
* In Java an enumerated type is represented as first-class object.
is there a definition in java for these first-class objects?
* Classes that do NOT support information hiding are NOT treated specially in Java
"treated specially" in what manner?
* Attributes incur a runtime penalty. However, the Sun hotspot JVM usually can eliminate the added overhead by “inlining” the methods where they are called.
Maybe anyone have a code-example? why can attributes trigger runtime errors??
* Both class associations and class compositions relationship may be of any multiplicity.
in compositions the n*n multiplicity is not possible, or ??
* Compositions may also have navigation methods, but these methods must NOT pass references to the owned objects. This is usually achieved by passing back a copy of the object rather than the owned object itself.