File I/O

Question 1

What are Character Streams used for?

Answer 1

Reading/writing files that contain ASCII/Unicode data
- Text files
- HTML files
- Program source files

Question 2

What classes do Byte Streams inherit from?

Answer 2

InputStream and OutputStream

Question 3

What classes do Character Streams inherit from?

Answer 3

Reader and Writer

Question 4

What are Byte Streams used for?

Answer 4

To read/write low level data
- Image pixels
- Audio data

Question 5

What is a file in terms of I/O streams?

Answer 5

Can be anything from a disk file to a physical device:
- Screen
- Keyboard
- Mouse

Question 6

What is a stream in terms of I/O streams?

Answer 6

An abstraction/interface between the programmer and file

Question 7

How does file I/O work in java?

Answer 7

• Opening the data source: Create a stream and associate it with the data source
• Accessing the data stream: Read and write from the file
• Closing the data stream: Close the stream to free up memory and clear any buffered data

Question 8

What are the two major types of byte streams in Java?

Answer 8

• FileInputStream & FileOutputStream
• DataInputStream & DataOutputStream

Question 9

What are the two major types of character streams in Java?

Answer 9

• FileReader & FileWriter
• BufferedReader & PrintWriter

Question 10

How do you create a FileInputStream in Java?

Answer 10

FileInputStream fileInputStream = new FileInputStream( filename );

Question 11

How do you create a DataOutputStream in Java?

Answer 11

DataOutputStream dataOutputStream =new DataOutputStream(new FileOutputStream( filename ));

Question 12

What are ObjectOutputStream and ObjectInputStream used for? Give examples.

Answer 12

• Used to read and write objects from file
• Can only read and write serializable objects (e.g. Java classes)

Question 13

What are Checked Exceptions?

Answer 13

• Problems that occur outside of a program’s control (e.g. Corrupt files)

-These must be dealt with

Question 14

What are Unchecked exceptions?

Answer 14

• Problems caused by the programmer/user (e.g. ArrayIndexOutOfBounds exception)
• These can be ignored