Java程序辅导

	Villanova	University										CSC	1051							www.csc.villanova.edu/~map/1051													Dr.	Papalaskari	
(instructor	or	TA	initials)	
Lab	1										Name:________________________	Checked:	______	
	
Objectives:	
• Learn	about	jGrasp	-	the	programming	environment	that	we	will	be	using	(IDE)	
• Compile	and	run	a	Java	program	
• Understand	the	relationship	between	a	Java	class	names	and	file	names	
• Practice	using	basic	Java	output	statements	and	adding	documentation	(comments)	to	your	source	code	
• Experience	Java	errors	
• Learn	the	basics	of	sequential	execution,	variables,	and	the	assignment	statement		
Instructions:	
• Complete	and	submit	the	preparation	before	coming	to	the	lab.	
• You	will	be	assigned	a	partner	for	this	lab.	Each	of	you	will	complete	the	lab	
separately.,	but	feel	free	to	help	each	other	learn!		
• If	both	are	stuck	or	don't	understand	something,	get	help	from	instructor	or	TA	
• At	various	points,	you	are	asked	to	compare	your	work	with	your	classmate’s	and	sign	
each	other’s	worksheet.		
o Be	sure	to	check	your	classmate’s	work	before	signing.	
o Who	is	right?	Who	is	wrong?	It	may	be	you	are	both	right,	but	ask	for	help	if	you	
are	not	sure.	
• When	finished,	demo	your	programs	and	get	your	worksheet	checked	and	initialed	
by	the	instructor	or	TA.	
	
Preparation:	Follow	the	instructions	to	install	Java	JDK	and	jGrasp	on	your	laptop.		1. Create	a	folder	on	your	computer	for	this	course.	You	are	responsible	for	organizing	your	files	for	each	lab	into	separate	subfolders.		For	example,	use	a	folder	Lab01	for	this	lab’s	files.		2. Download	and	save	Lincoln.java.	Open	the	file	using	jGrasp.		3. In	jGrasp,	compile	Lincoln.java	by	clicking	big	green	plus	button:		
o Note	that	you	now	have	a	file	Lincoln.class in	the	same	folder		
o It	is	NOT	required	(or	desirable)	to	open	that	file,	but	you	may,	if	you	are	curious.	It	is	not	meant	to	be	read	by	humans!	It	contains	the	bytecode	that	you	will	run,	as	instructed	in	the	next	step.		4. In	jGrasp,	run	Lincoln.class by	clicking	on	the	red	runner	button:			
o This	causes	your	program	to	execute	its	instructions	
o See	the	output	of	this	run	in	the	interactions	(lower	pane)	in	jGrasp		5. When	finished,	submit	the	files	Lincoln.java	and	Lincoln.class	through	blackboard	under	the	assignment	“Lab	1	Prep”	
 
	Villanova	University										CSC	1051							www.csc.villanova.edu/~map/1051													Dr.	Papalaskari	
	
Part	A:		Running	and	modifying	code	
 
1. Open, compile and run the other two examples from chapter 1: Lincoln2.java 
and Lincoln3.java 
These work fine but are hard to read. Practice fixing up the code and note that you can 
use the “Generate CSD” and “Remove CSD” buttons to make the job easier. Show your 
work to a classmate. 
Classmate signature: ________________________________________  
2. Open	Lincoln.java again. Edit it by renaming the class to MyLincoln. 
o Run the program. What happens? 
 
 
 
o Save this modified program as MyLincoln.java and run MyLincoln. 
o Add or modify the comments at the top of the program to include: 
§ Your	name	(you	are	now	the	Author)	
§ A	note	about	the	original	author	("based	on	a	program	by	Lewis	&	Loftus")	
§ Today's date	
§ A very short summary of the modifications you made	
o Re-compile	and	run	to	make	sure	it	still	works	(there	should	be	no	difference	in	its	functionality)	
Classmate signature: ________________________________________  
Part	B:		Debugging	3. Experiment	with MyLincoln.java	and	introduce	some	errors	(“bugs”).	Try	some	of	the	following	to	see	what	happens	when	you	re-compile	and	(if	successful)	run	the	program.	If	you	get	an	error	right	away,	mark	it	as	“syntax,”	if	it	compiles	but	you	get	an	error	when	you	try	to	run	it,	mark	it	as	“runtime,”	and	if	it	compiles	and	runs	but	produces	a	wrong	(or	different	result	than	intended,	which	we	take	to	be	the	original),	mark	it	as	“logic”.	
• Change	the	first	println to	print     Error: ______________ 
• Change	the	second	println  to	bogus     Error: ______________ 
• Remove the semicolon at the end of one of the statements  Error: ______________ 
• Remove the last brace of the program    Error: ______________ 
• Change main to man       Error: ______________ 
• Something else you tried?       
_____________________________________________ Error: ______________ 
 
Classmate signature (compare notes): ________________________________________ 
	Villanova	University										CSC	1051							www.csc.villanova.edu/~map/1051													Dr.	Papalaskari	
 
Part	C:		Creating	a	program	from	scratch	
 
4. Using MyLincoln as a model, create a new program named MyQuote and make it do 
the following:   
• Print out a new quote of your choosing 
• Add variables to the program such as: 
 
int x = 42; 
int count = 100; 
double pi = 3.14; 
String name = "Kripke"; 
 
 (we will be studying variables next week; for the moment we are just experimenting!) 
• Add more output statements to use your new variables, such as: 
 
System.out.println ("Howdy " + name); 
System.out.println ("The answer is " + x); 
System.out.print ("Counting... up: " + (count + 1)); 
System.out.println (" ... and\n ... down: " + (count - 1)); 
System.out.println("The perimeter of a circle with radius " + 
     x + " is " + (2* pi * x)); 
 
• Be sure to pay attention to correct structure, syntax, indentation, and comments!  
 
Feel free to be creative! Compile and run your program to make sure it works and that it prints out the values of 
your variables where you expect them. Try changing it around to use different values or different variable 
names (we are using the names x, count, and name here). Be sure to stay away from the reserved words (see 
fig 1.18, p32). We will be learning a lot more about variables, but for the moment you can just experiment with 
whatever comes to mind. Don’t worry about making mistakes – that’s the best way to learn. 
 
 
Classmate signature: ________________________________________ 
 
 
 
 
REMINDERS:  
1) Review worksheet.   
• All questions answered  and in agreement with partner 
• Signatures from your partner where required 
 
2) Demo your programs and get initials from instructor or TA on this worksheet 
2) Detach and hand in the comments sheet.  
	Villanova	University										CSC	1051							www.csc.villanova.edu/~map/1051													Dr.	Papalaskari	
	
	Villanova	University										CSC	1051							www.csc.villanova.edu/~map/1051													Dr.	Papalaskari	
Lab	1	Comments			Name:_____________________	Checked:	______			What	was	the	most	valuable	thing	you	learned	in	this	lab?								What	did	you	like	best	about	this	lab?									Was	there	any	particular	problem?										Do	you	have	any	suggestions	for	improving	this	lab	as	an	effective	learning	experience?