Files and Exceptions

Question 1

What does the cd command do in the shell?

Answer 1

Change Directory

Question 2

Explain this permission

-rw-r–r–

Answer 2

Read/write for the user, read for the group and others

Talking about files not a directory

Question 3

Explain this permission

-rwxr-x—

Answer 3

Read/Write/Execute for the user, read for the group and execute for others
Talking about files not a directory

Question 4

Explain this permission

dr-xr-xr-x

Answer 4

Talking about a directory

Execute/Read for the user and group and just execute for the others

Question 5

What is an exception?

Answer 5

An event, which occurs during the execution of a program that disrupts the normal flow of the program’s instructions

Question 6

What is an error?

Answer 6

Indicates a serious problem that a reasonable application should not try to catch

Question 7

What is the difference between an exception and an error?

Answer 7

Try to catch an exception, don’t try to catch an error

Question 8

Why does Java allow unchecked exceptions?

Answer 8

Wanted to have unchecked exceptions that should be used when calling code cannot recover

Question 9

What is the purpose of a finally block?

Answer 9

Used to execute important code such as a closing connection because always executed whether an exception is handled or not

Question 10

Give the disadvantages of files over relational databases

Answer 10

• Data redundancy and inconsistency
• Difficulty in accessing data
• Integrity problems
• Security problems
• Atomicity of updates
• Concurrent access

Question 11

Give the advantages of files over relational databases

Answer 11

Cheaper

Doesn’t require special knowledge