When an IOException generally occur and what action should I take to properly handle it? [closed]

Question

I am using File Input/Output streams. I know that reading a non-existent file from program using FileInputStream will give FileNotFoundException. Right? So I can catch this excpetion and can return null or 0 value(depends on return type of my method performing all this reading operations) on Exception to convey the calling program that file does not exist and should create the one.

But I don't know when IOException generally occurs and what is the exact reason I should convey to calling program that 'this' has happened because of 'that'. I exactly don't know what is 'this' and 'that' here.

Anybody please elaborate me in what cases does the IOException can occur and what specific action should I take in such case. Please help. Thanks.

Answer 1

What is an IOException

An IOException is any unexpected problem the JVM encounters while attempting to run a program. Possible problems that it may encounter are:

• attempting to read from a file that does not exist
• attempting to write to a file that has an invalid name (a slash or a question mark in the title should do it)
• attempting to read the next token in a file when there are no more tokens.

When an IOException is thrown, it means that whatever is throwing the exception (perhaps a try{}-catch block that reads data from a file) can throw an IOException, for example if the file is not found, corrupted, etc, or when the file is otherwise unable to be read, or any other of a list of issues that can occur with the IO package and it's extensions.

What to do when you encounter an IOException?

When you encounter the IOException, you could log it or print an error message. If you are reading from a file that does not exit, you could create one to avoid future exceptions. A lot depends on what you are doing. If you are debugging, printing the stacktrace is always helpful.

Refer to the javadoc

Answer 2

You can do the following things:

1. Log the Exception information on a log file. You can use the following method to populate the Exception information.

2. Try to close the InputStream/OutputStream if it is not null when the IOECeption happens in reading / writing.

3. Throw an Exception of your own with meaningful message to let user know what happens.