Chapter 18: Files

Question 1

Describe the shift operators

Answer 1

> > signed right sheft: 1 shifted in left if number is negative
a &laquo_space;b a shifted b bits left: 0s shifted in
> unsigned right shift: 0s shifted in

Question 2

Describe integer bitwise operators

Answer 2

| Integer bitwise or is the same as addition when the numbers have no bits of the same value

* ^&raquo_space; &laquo_space; individually on bits

Question 3

How do we read an input file into a program?

Answer 3

input file -> file input stream -> input stream reader -> buffered reader -> program

Question 4

What makes up a file reader?

Answer 4

File input stream, input stream reader

Question 5

How do we output to a file?

Answer 5

program -> print writer -> output stream writer -> file output stream -> output file

Question 6

What makes up a file writer?

Answer 6

Output stream writer, file output stream

Question 7

What is a print writer?

Answer 7

Wraps up output stream writer and provides println, printf, print etc. to print whole lines of text
new printwriter(output stream writer).

Never throws exceptions! instead you have to use checkerror

Question 8

What is a print stream?

Answer 8

subclass of output stream. Has print, println, printf and methods for writing bytes

Question 9

What is an output stream?

Answer 9

Allows writing of bytes. Provides a view of data as byte stream. write() writes a byte given an int

Question 10

What is an IO exception?

Answer 10

There is a lot that could go wrong when reading files. Most operations are capable of throwing exceptions.
A checked exception

Question 11

What is an input stream?

Answer 11

provides a view of data as a sequence of bytes

Question 12

What is an input stream reader?

Answer 12

When we wish to treat an input stream as a sequence of characters, we wrap it up in an input stream reader

Question 13

What is a buffered reader?

Answer 13

Provides an instance method to read a whole line of characters in one go. Wraps up an input stream reader

Question 14

What is a file input stream?

Answer 14

To read bytes from a file we use an instance of file input stream. A subclass of input stream

Question 15

What is a file reader?

Answer 15

We can wrap a file input stream into file reader to read characters from a file
of we can wrap an input buffer to read a line of bytes

Has a input stream reader and is a input stream reader at the same time

Question 16

What is an output stream writer?

Answer 16

We can wrap output stream in output stream writer to provide a view as a sequence of character instead of bytes

Question 17

What is a file output stream?

Answer 17

Writes bytes to a file

Question 18

What is a file writer?

Answer 18

File output stream can be wrapped in output stream writer to write character to file instead of bytes

Question 19

What does File allow us to do?

Answer 19

Examine properties of files e.g. exists()

Question 20

What is data output stream?

Answer 20

Allows us to write values of any primitive type to a file rather than writing bytes. 
Subclass of output stream
Instance of data output stream is a wrapper around an output stream

Question 21

What is data input stream?

Answer 21

Allows us to read values from a binary file that was written using data output stream
Subclass of inputstream
Wrapper around an input stream

Question 22

Give examples of input/output streams in the standard API

Answer 22

Err is an output stream
In is an input stream
Out is an output stream

Question 23

Describe assignment as an expression

Answer 23

= is an operator
it takes a variable as left operand and an expression as the right.
means we can write x = (y = 5) + (z = 3 + 4)
Right associative

Question 24

What is an initial value?

Answer 24

If you declare a variable but don’t give it a value, it is given a default initial value.