Cracking the Java Coding Interview pdfdrive com

Question Whats the difference between notify() and notifyAll()? (Core Java)
Answer notify() is used to unblock one waiting thread; notifyAll() is used to
unblock all of them. Using notify() is preferable (for efficiency) when only one
blocked thread can benefit from the change (for example, when freeing a buffer
back into a pool). notifyAll() is necessary (for correctness) if multiple threads
should resume (for example, when releasing a "writer" lock on a file might
permit all "readers" to resume).
Question Why can't I say just abs() or sin() instead of Math.abs() and
Math.sin()? (Core Java)
Answer The import statement does not bring methods into your local name
space. It lets you abbreviate class names, but not get rid of them altogether.
That's just the way it works, you'll get used to it. It's really a lot safer this way.
However, there is actually a little trick you can use in some cases that gets
you what you want. If your top-level class doesn't need to inherit from anything
else, make it inherit from java.lang.Math. That *does* bring all the methods into
your local name space. But you can't use this trick in an applet, because you
have to inherit from java.awt.Applet. And actually, you can't use it on

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have to inherit from java.awt.Applet. And actually, you can't use it on
java.lang.Math at all, because Math is a "final" class which means it can't be
extended.
Question Is is possible for an EJB client to marshall an object of class
java.lang.Class to an EJB? (EJB)
Answer Technically yes, spec. compliant NO! - The enterprise bean must not
attempt to query a class to obtain information about the declared members that
are not otherwise accessible to the enterprise bean because of the security rules
of the Java language.
Question Is it legal to have static initializer blocks in EJB? (EJB)
Answer Although technically it is legal, static initializer blocks are used to
execute some piece of code before executing any constructor or method while
instantiating a class. Static initializer blocks are also typically used to initialize
static fields - which may be illegal in EJB if they are read/write - In EJB this can
be achieved by including the code in either the ejbCreate(), setSessionContext()
or setEntityContext() methods.