Deadlines

1
01-11

• Deadlines
• Assignment 1 due today
• Assignment 2 on the web now, due 1/18
• Last time
• OOP terminology
• The System class and interface to the operating
  system
• User input and the Scanner class
• This time
• Quick review of OOP
• Quick review of the Scanner class
• Program to prompt for a name and say hello to it
• Input from files
• Command-line arguments
• The String class

2
From Last Time

• The main concepts in OOP
• Classes represent abstract collections of
  individuals (instances or objects)
• The class defines how to construct an instance
  and also what methods all instances respond to
• Objects (class instances) denote nouns ("an
  employee") and methods denote verbs ("return
  salary")
• When talking about an object you need to know its
  class, aka its data type (e.g. number, String,
  Scanner, PrintStream, System)
• When talking about a method you need to know its
  signature (its name, number and types of
  arguments, and what information it returns)
• Things to ask when learning about a new class
• how do I make the class available to my program?
• how do I construct an instance of the class (the
  constructor)?
• what methods can I then call on instances I
  construct?

3
Last Time (cont.)

• The Scanner class
• not a system-defined class (in version 1.4.2) so
  we have to make the Scanner.class file available
  to the Java compiler and Java runtime environment
• one way to do so is by putting Scanner.class in
  the working directory
• there is no such thing as a "Scanner literal" so
  we have to call the constructor explicitly
• Scanner s new Scanner(System.in)
• after we have an instance, the first method we
  learned about was nextLine()
• no arguments
• returns a String, which is the next line
  available from its input source. Technically
  this is the sequence of characters up to, but not
  including, the next newline character