Common Exceptions by Fiona Baxter

NULL POINTER - MH

2016-01-05 09:51:09 UTC

A NullPointerException in a RunTimeException that is caused when a user attempts to use an object with a null value.

In order to avoid this occurring you could init (set the value to 0) or check that it is not a reference variable without value.

ClassNotFound - Pat

2016-01-05 09:52:00 UTC

Class not found is where Java Virtual Machines tries to find a class that has been referenced later on into the code, and it isn't found. This could be an easy error to make. Example being if you called a class 'Example' but then later wanted to reference it as 'example'

ArrayIndexOutOfBounds - MN

2016-01-05 09:52:53 UTC

When a call to an array index which doesn't exist. For example if an array has a length of 2 and the program tries to get the third value.

This code would produce such an exception;

String[] arr = {"0", "1"}; String l = arr[2];

This error should be handled if there is a chance that a user or the program may try access an index of the array which may not be there.

Arithmetic

2016-01-05 09:54:58 UTC

Thrown when an exceptional arithmetic condition has occurred. For example, an integer "divide by zero" throws an instance of this class.

NumberFormat PB

2016-01-05 09:56:05 UTC

A Number Format Exception is when someone is trying to

convert a string into a number. So they will write out a string and the tell the code to print out a value which will not be defined as it will be looking for a string instead of a number.

IO Exceptions

2016-01-05 09:56:11 UTC

An IO exception is and Input/Output exception.

Assume the scenarios as below:

1. You were reading network file and got disconnected.

2. Reading local file which is not available anymore.

3. Using some stream to read the data and some other process closes the stream.

4. You are trying to read/write a file and don't have permission

5. You were writing a file and disk space is not available anymore.

All these scenarios result into IOException.

You can catch specific errors in ‘catch’ blocks of code, but there is a statement that catches all IOExceptions and returns a general message.

Arithmetic

2016-09-20 11:07:49 UTC

Thrown when an exceptional arithmetic condition has occurred. For example, an integer "divide by zero" throws an instance of this class.

NumberFormat

2016-09-20 11:07:53 UTC

A Number Format Exception is when someone is trying to convert a string into a number. So they will write out a string and the tell the code to print out a value which will not be defined as it will be looking for a string instead of a number.

ArrayIndexOutOfBounds - JD

2016-09-20 11:08:07 UTC

Thrown to indicate that an array has been accessed with an illegal index.
The index is either negative or greater than or equal to the size of the array.

IO Exception

2016-09-20 11:14:31 UTC

Lily
IO Exception is a class of Exception that was raised due to all Input/Output contingencies. The file operations like read(), write() and close() etc. are OS dependent and are declared as native methods.