Week 3: week of Sept 10

More loops:

Notebook example:

Notebook1: 
	demo of storeNote, numberOfNotes, showNote
	look at code:
		ArrayList
		get/size
		inspector
	Problem: what if we forget which note we want?

Notebook2:
	A *loop* to show all notes
		while version
		for-each version
		(for loop, or "classic for loop", is also a possibility)
	
Where else would this help?

	LabClass project
	

Wednesday:

Look at LabClass
for:each versus while loops in Notebook

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LabClass: add a check against duplicates.

	if (searchStudent(newStudent.getStudentID())) {
	    System.out.println("Student with ID " + newStudent.getStudentID() + " already enrolled");
	    return;
	} else {
	
============================================================

   for:each loop versus while loop:
	
	int totallen = 0;
	for(String note : notes) {
		totallen += note.length();
	}
	
    While loop:
	int totallen = 0;
	int n = 0;
	while (n<notes.size()) {
		String note = notes.get(n);
		totallen += note.length();
		n++;
	}
	
   Classic "for" loop:
   
	int totallen = 0;
	for (int n = 0; n < notes.size(); n++) {
		String note = notes.get(n);
		totallen += note.length();
	}

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Numeric example (Wednesday)
	
    public bool isPrime(int n) {
        int div = 2;
        int top = n-1; 	// top = (int) Math.sqrt(n)
        while (div < top) {
        	if (n % div == 0) return false;
        	div ++;
        }
        return true;
    }
   

now *print* primes from 1 to 100:

	for (int i = 1; i<=100; i++) {
	    if (isPrime(i)) {
	    	System.out.println("" + i + " is prime");
	    }
	}
		
==========================================================================================	
Monday:
for loops / nested loops

    public void triangletable() {
        int row,col;
        for (row = 1; row <= 15; row++) {
            for (col = 0; col<row; col++) {
                System.out.print("**");
            }
            System.out.println();
        }
    }

or:

    public void triangletable() {
        int row;
        for (row = 1; row <= 15; row++) {
            triangleRow(row*2);
        }
    }


    public void triangleRow(int width) {
    	int col;
        for (col = 0; col<width; col++) {
            System.out.print("*");
        }
        System.out.println();
    }

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Friday: 

Demo of MailSystem
	Note that it would be quite hard to simulate multiple users
	without the BlueJ object bench. 
	
	Look at MailItem

	MailClient:
		"this" keyword: useful for dealing with name conflicts
		
	demo of creating three users and several messages, and
	using the Inspector
	
	MailServer:
		items: List<MailItem>
	loops:
		howManyMailItems(string who)
		for:each loop
		
		getNextMailItem(String who):
		Iterator loop in original version; could also be while loop
			do the while version
			forgot i++
			used <= instead of <
		
	demo of reading messages, and watching the inspector view change
	
	Demo of sending a message and setting a breakpoint in printNextMessage(),
	and running the debugger.

	(This crashed a couple times for me)
	
	5. Class diagrams v object diagrams
		class arrow: NOT just for subobjects
		
	What do the arrows mean for object diagrams? "Uses" relationship
		
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Notebook search loop

javadoc and String page; find note.contains(s)

"return loop": use return statement to terminate when found
	isPrime was an example of this
	so was LabClass.searchStudent
	
"print all" loop: terminate at end of list, regardless of data found
	Notebook.searchNotes is an example
	
"find first" loop: compare to example on page 94
	
	
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