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0) Last time- string/number conversions, I/O, and Math class
- with group, do exercise (from last time)

1) Administrative
- hw: codelab Wed, A1 out
- review 1.1-1.3, read 4.1-4.3 (no presentations)

2) Split in groups and go over 4.4 and 4.7

3) Highlights of material

	A) Methods: sets of instructions you can use by "calling" the method
		- where do you define them?  -inside classes
		- how do you call one from inside the same class?  -this.name(...)
		- "this" is optional and means "this object"
		- how do you call one from inside a different class?
			- obj.name(...) or Class.name(...) if static
		- when you call, computer jumps over to that code, then jumps back

	B) How do you define a method?
		visibility [static] returnType name(parameter list) {
			stmt1; stmt2;
		}
		- what does public mean? -can call that method from anywhere
		- what does private mean? -can only call from within same class
		- what does static mean? -it's a class method, not linked w/ obj
		- what do parameters mean? -info it expects to get when called
		- what does return type mean? -info it promises to pass back
	
	C) Inside a method: local variables
		- variables can either be data members or local variables
		- data members are permanent to the object; locals aren't
		- declared inside a method and only exist inside that method
		- (anything you declare in main - all vars you've worked with)
		- looking at class, realize that it's not linear code, so even
		  if a var appears higher up it may not exist lower down
		- you can use data members inside method (do not declare again!)
		- what if you declare one with same name? local, overrides
		- can get to them again using this.name (even if private)
		- parameters are local variables too
		- "scope" of a variable: where it exists

	D) Passing and returning
		- IMPORTANT: what's printing? what's returning? DIFFERENT!
		- arguments are assigned to corresponding parameters 
		- pass by value: values are copied, no link afterwards
			int x = 1;		public int addOne(int i) {
			addOne(x);			i = i + 1;
			x = addOne(x);		return i;
						}
			* first call: nothing gets changed! (i disappears, x same)
				- imagine addOne(5);   (number 5 cannot change)
			* second call: assigning return value, so now it's changed
			* parameters are local variables- can assign to them
			* does it matter what the parameter name is?
				- no, but it can override data members
		- return is by value as well: value replaces method call expression
		- the return statement: by itself, with expression, stops execution
		- "method composition"- another term for nesting calls
		- in diagram: parameter types in parens, return type after

	E) In memory- stack frames (just FYI)
		- object data held in heap
		- area called the stack holds local scratch space for methods
		- each one has a chunk called its stack frame
		- contains space for params, local vars
		- when it returns, return value is copied and frame disappears
		- local vars are truly gone, but data members stay in object

	F) Questions??

4) Exercises- fill in main class as we go

	A) Write a method that takes 3 ints and returns the average as a double.
		public double average(int a, int b, int c) {
			return (double)(a+b+c)/3;
		}

	B) Write a method that takes a prompt and returns a string of input. Make
	   it static, b/c it won't use any instance data to operate.
		public static String readInput(String prompt) throws IOException {
			System.out.print(prompt);
			BR buf = new BR(new ISR(System.in));
			return buf.readLine();
		}

	C) Write a method that takes a prompt and returns an integer from input.
	   It should not duplicate code from before, but just call readInput().
		public static int readInt(String prompt) {
			return Integer.parseInt(getInput(prompt));
		}

	D) Write a method that returns a double.
		public static double readDouble(String prompt) {
			return Double.parseDouble(getInput(prompt));
		}
	
	E) Fill in a main method body that uses these to input three ints and
	   print the average.
		int a = readInt("Enter first integer: ");
		int b = readInt("Enter second integer: ");
		int c = readInt("Enter third integer: ");
		System.out.println("The average is " + average(a,b,c));

5) Summary
- defining and calling methods
- parameters and return values
- local variables vs. data members

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