Threading
What is a process?
A program/ instance of an application that is currently being executed by the OS, which may have more than one thread of execution
What is resource contention?
When multiple threads try to manipulate the value of a shared resource at the same time
What are some differences between TCP/IP and UDP?
TCP is slower & more reliable, sends/receives in a certain tracked order
UDP doesn't require a connection and can deliver even if not all components of the data are complete
What is the difference between BFS and DFS?
BFS investigates all surrounding nodes before moving on, DFS utilizes recursion and continues deeper one node at a time
What does Observer do?
the concrete observer implements Observer and notify()s when the subject's trigger has been observed
What are the 4 thread states?
New, Runnable, Running, Dead
What is the difference between extending Thread and implementing Runnable?
With Thread, the run() method is optional (Runnable has no option but to override it), there is single inheritance, and the subclass technically is a thread. Implementing Runnable is generally better design choice since it is responsible for less and can be restarted.
What are the 4 layers to the DoD/ TCP/IP model?
Application, Transport, Internet, Network Access
What are the differences between a heap and BST?
A heap places highest or lowest at top and doesn't care about horizontal order, BST maintains a sorted order where each node's left child is smaller and each right child is larger
What'd you do to celebrate Earth day?
!!!!
Why call start() on your thread instance instead of run()?
run() executes it in the main thread, start() actually executes it in a separate thread
Describe join() and sleep()
Join(), used on thread you are waiting for, enforces only proceeding when that thread is finished
Sleep() is called directly on Thread class to make the calling class relinquish its processor time for the specified ms
What do sockets send data as and what do you need to use to make it readable?
They send streams in bytes or byte arrays, thus we need Scanner and PrintWriter
List out all the steps to BFS
As long as queue is not empty and options are not in already-visited set:
dequeue next vertex and if its not the end then add each of its neighbors to the queue next
keep checking till path found or queue empty
What changes for an inner class if it is declared as static?
It cannot directly access the outer class’ state and behavior, but it can be created without an instance of the outer class
What state is a thread in if it is trying to enter a synchronized block of code that another thread currently has the lock on? (And what does it move to after?)
Blocked until the lock is obtained, then becomes Runnable
Why would you generally not put ALL of the contents of your run() method in a synchronized block?
Then the threads will just run sequentially instead of concurrently; and why are you even using threads at that point bro
What is the communication flow between client and server when using TCP
-Server begins listening on a specific port (using accept())
-Client establishes connection on server's port
-Use streams to send/receive data back and forth
What data structures does Dijkstra's algorithm use in implementation?
Map of vertices & their path tuples, and a priority queue for the path tuples
When are syntax & runtime errors reported in Java?
Syntax reported when compiled to bytecode, runtime reported at execution
In a system called tech booth, there is a lights person, captions person, and sounds person, each representing threads that need two computers each. There are three computers. What would lead to deadlock?
Each person tries to claim one computer and won't give up their lock on it till they do their job with two computers (but cannot ever obtain the second since everyone has one and is waiting on the same thing)
In a system called tech booth, there is a lights person, captions person, and sounds person, each representing threads that need two computers each. There are three computers. What would you change about this scenario to make it a producer-consumer system?
There must be a computer manufacturer, and I suppose the tech booth people break the computers after each use like some sort of maniacs
What's the difference between simplex, half-duplex, and full-duplex? (And what are Java sockets?) Optional: How about multiplex?
Simplex is only one direction (and not back)
Half-duplex can be sent both ways but only one at a time
Full duplex can be sent both ways simultaneously, which is what Java sockets are
Multiplex can send multiple streams/signals at once in the form of complex signals
Draw a graph and then diagram traversing it with Nearest Neighbor
:) Guys I can't input diagrams in answers without paying sorry
Explain and/or diagram the MVC pattern
Model = Application building blocks
View = Current state of the model in viewable form
Controller = Translates actions