- A class’s superclasses don’t have to implement Serializable in order to be serialized
- if a superclass doesn’t implement Serializable then it’s constructor will run during deserialization
- A transient variable’s state is lost during serialization, but a volatile variable’s state is not lost
- Java:Volatile variable
- Transient Variable
- NumberFormat, Calendar, DateFormat are abstract classes. Use the getInstance method to get NumberFormat instances.
- The + quantifier in a regular expression indicates 1 or more occurrences, * indicates 0 or more, [] just one character in the group, () indicates a whole group match.
- The default separator in Scanner class is a blank NOT a comma
- Multiple threads can be created using the same Runnable object, but a given thread can be started only once.
- Thread.yield(): Causes the currently executing thread object to temporarily pause and allow other threads to execute.
- Thread.join(): Waits for this thread to die.
- Wait(), Notify(), NotifyAll() methods
- Low coupling: classes know the least possible about each other, is preferable over tight coupling.
- High cohesion: Each class has well focused responsibilities. Is preferable over low cohesion.
- Polymorphism does NOT apply to static methods.
- Instance variable cannot be referenced from static method
From: http://sitestree.com/?p=4883
Categories:Java Short Notes, SCJP
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Post Data:2011-09-04 06:32:26
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