1. CS 302 Week 13
Jim Williams, PhD

2. This Week Team Lab: Processing Optional Labs More Exceptions
File Output and Input

3. More Exceptions Exception Message
What to do when you have to catch an exception and aren't sure yet how to handle?
e.printStackTrace()

4. If methodA doesn't throw an exception then output is?
public static void main(String[] args) throws MyException {
try {
methodA( args);
System.out.print("B");
} catch( MyException e) {
throw e;
System.out.print("C");
} finally {
System.out.print("D"); }
System.out.print("E");
BCDE
CDE CD
BDE
try it

5. If methodA throws MyException then output is?
public static void main(String[] args) throws MyException {
try {
methodA( args);
System.out.print("B");
} catch( MyException e) {
e.printStackTrace();
System.out.print("C");
throw e;
} finally {
System.out.print("D"); }
System.out.print("E");
BCDE
CDE CD
BDE
try it

6. What is the correct output?
Hello Fred
100,3.14
Hello Fred
100,
00100,3.14
public static void main(String[] args) {
String name = "Fred";
int num = 100;
double dNum = ;
System.out.printf("Hello %6s\n", name);
System.out.printf("%05d,%.2f",
num, dNum); }

7. Files

8. What does this do? String name = "myfile.txt";
File aFile = new File(name);
PrintWriter output = new PrintWriter( aFile);
output.printf("This is the contents of %s.\n", name);
output.close();

9. What does this do? PrintWriter writer = null; try {
writer = new PrintWriter( SEEDS_FILENAME);
for ( Seed s : seeds) {
writer.printf("%f, %f\n", s.getX(), s.getY()); }
} catch ( IOException e) {
System.err.println("Unable to write to " + SEEDS_FILENAME);
} finally {
if ( writer != null) writer.close();

10. What does this do? File file = new File(SEEDS_FILENAME);
Scanner inFile = null;
try {
inFile = new Scanner(file);
while (inFile.hasNext()) {
//process each line of the file }
} catch (FileNotFoundException e) {
e.printStackTrace();
} finally {
if (inFile != null) inFile.close();

11. Relative vs Absolute Paths
Relative - based on current location
Absolute - based on fixed location

12. From within log what is a relative path to tasks?/
meta
log
mylyn
taskListIndex
segments
tasks
contexts
plugins
history
../mylyn/tasks
/meta/mylyn/tasks
./mylyn/tasks
../tasks

13. From within tasks what is a relative path to mylyn?/
meta
log
mylyn
taskListIndex
segments
tasks
contexts
plugins
history
/meta/mylyn
../mylyn
./../mylyn/tasks ..

14. From within tasks what is an absolute path to log?/
meta
log
mylyn
taskListIndex
segments
tasks
contexts
plugins
history
/meta/log
../../log
./meta/log
/log