1. SE-1021 Software Engineering II
7/29/2018
SE-1021 Software Engineering II
Week 9, Day 2
Exceptions (briefly)
Files
Bits and Bytes
Week 9, Day 3
Lab 8 Complete Demo
Lab 9: Start writing/reading bmsoe files
SE-1021
Dr. Josiah Yoder
Slide style: Dr. Hornick
Dr. Josiah Yoder

2. To catch individually, what order?
Exception
IllegalArgumentException
IOException
NumberFormatException
RuntimeException
SE-1021
Dr. Josiah Yoder
Slide style: Dr. Hornick

3. Slide style: Dr. Hornick
… } catch ( ) { } catch ( ) { }
SE-1021
Dr. Josiah Yoder
Slide style: Dr. Hornick

4. Slide style: Dr. Hornick
Review / New Material
How many bits are there in a byte?
Write all the three-bit binary numbers.
How many values can you encode with a single byte?
SE-1021
Dr. Josiah Yoder
Slide style: Dr. Hornick

5. Slide style: Dr. Hornick
ASCII table
First digit
LF – Line feed (\n) 0x0A
CR – carriage return (\r) 0x0D
Second digit
SE-1021
Dr. Josiah Yoder
Slide style: Dr. Hornick

6. Slide style: Dr. Hornick
ASCII
How many bytes do you need to store one ASCII character?
How many bits do you need to store one ASCII character?
SE-1021
Dr. Josiah Yoder
Slide style: Dr. Hornick

7. Slide style: Dr. Hornick
Files
A file is a container for a sequence of bytes stored on the computer’s hard drive
Each byte is made up of 8 bits
An ASCII character is one way of storing letters.
“Plain text files” often use ANSI ASCII encoding.
To encode other languages, we need to use a different encoding.
SE-1021
Dr. Josiah Yoder
Slide style: Dr. Hornick

8. Slide style: Dr. Hornick
Using files in Java
Both files and folders (Directories) are represented with a “Path” object as discussed earlier
We can open the file to get the byte stream
(Coding example)
Path path = Paths.get(…);
boolean isDir = Files.isDirectory(path);
SE-1021
Dr. Josiah Yoder
Slide style: Dr. Hornick

9. Reading the bytes from a file
InputStream is an abstract class to represent reading bytes
FileInputStream is a class that reads bytes from a file
You can also get input streams to read bytes from the network, a byte array, etc.
Use inputStream.read() to read one byte
Returns -1 (an integer) if the byte is not read
Use inputStream.read(…) to read multiple bytes at a time
SE-1021
Dr. Josiah Yoder
Slide style: Dr. Hornick