CS108

2/12/2015

Concepts: Java Servlets

• Use New Dynamic Web Project
• Create new servlets to
• Listener is designed to do setup (i.e. initializing the sessions)
• Session attributes act like hashMaps
• You can creat

2/3/2015

Concepts: Threading

• start vs. run:
  • start will actually fork off a new quesiton but run will keep the run method of the child thread running on the main thread itself
*

1/29/2015

Concepts: Databases

• We'll be using MySQL Monitor to interact directly with MySQL

• Key characteristics of a database:

  • Persistent Storage
  • Application Access (applications can acces the data)
  • Transaction management (this is not supported by a file system): Database rolls back if either end of the transaction fails
  • Efficient Searching (not necessarily supported by traditional file system)

• To access the database you need:

  1. username
  2. password
  3. database server
  4. database name

• Java Database Connectivity (JDBC): built-in java library that works with SQL database.

1/27/2015

Concepts: Anonymous Functions, Lambda Functions

• You can sort with an anonymous lamda function, you don't need to create the entire comparable class - just need to create that one function:

Collections.sort(ingredients, (x, y) -> (return(x.getGrams()-y.getGrams()));  

Note that this anonymous function has the same context as the surrounding program in JRE 8 (JRE 9 apparently has the concept of closure)

1/22/2015

Concepts: Java Swing

• java.awt abstract window types

JFrame theFrame = new JFrame("Swing Example");  
theFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  

(this way the entire application is still running even when you close a window)

• You can set the "look and feel" of an application
• Use ActionListeners to catch changes to buttons (like a JS callback)

1/8/2015

Concepts: Autoboxing, Templating, Generic Types, JUnit

• Remember you can't create collections of primitive types in Java, (i.e. you have to use Integer objects instead of ints)
• Autoboxing: We can autobox wrapper objects like Integers: myIntList.add(5) is equivalent to myIntList.add(new Integer(5))
• Autounboxing: int x = myIntList.get(0) Though this list is made of Integer objects, Java will auto-unbox the int value for you
  • You do need to be explicit to unbox in this case: a.get(0).intValue() == b.get(0).intValue()

Generic Types

• You can use generic type parameters to template objects in Java:

public class Pair<T> {  
    private T a;
    private T b;
}
...
Pair<Integer> iPair = new Pair<Integer>(1,2);  

• Beware! You cannot instantiate new generic types inside a class that uses a type parameter. This is because Java doesn't know what type it is at run-time (due to backwards-compability in the internal implementation of types because only the compiler knows about the type)

JUnit Testing Frameworks

• test stub - sample item returned that can be used to test a program (i.e. a single word returned by the hangman initialization function)
• test harnesses - stands in as a potential user of the program you're writing