Object Oriented Programming

Extra Reading

Primary goals in creation of Java:

Java typically is slower and uses more memory than C++
- overhead due to interpreter from Java bytecode to machine code

Java has an automatic garbage collector
- programmer determines when objects are created
- Java runtime recovers memory once objects are no longer in use
- when no references to an object remain, unreachable memory becomes eligible to be freed by the garbage collector
- memory leaks still occur if code hols references to objects no longer needed
  - in this case throws null pointer exception
garbage collection occurs at idle, or is triggered if there is insufficent memory on the heap to allocate a new object, which can cause program to stall
explicit memory management and pointer arithmetic is not supported
variables of primitive data types are stored directly in fields (for objects) or on the stack (for methods) rather than on the heap

Keywords applied to methods

public: method can be called from code in other classes, or class may be used by classes outside the class hierarchy
static: associated only with the class, and not a specific instance of the class
- can be invoked without a reference to an object
- cannot access class members that are not also static
void: main method does not return a value