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Java exception handling interview questions and answers

Q1. What is the difference between a runtime exception and a checked exception? A1. You must either catch or throw a checked exception. The unchecked exception (aka Runtime exception) does not have to be explicitly handled. Q. So, when to use checked exception, and when to use unchecked exception? A….

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Java String & Array limitations and OutOfMemoryError

Q1. What is the maximum possible length of a Java String & how much heap space do you need to store the maximum possible String object?
A1. A Java String internally uses a char array (i.e. char[]) and the indices of an array is an integer. The maximum value of an integer is Integer.MAX_VALUE, which is 2^31 – 1 (or approximately 2 billion). So, you can store a file up to 2 GB in size as a String, and for which you need at least 4 GB memory to store as each char is 2 bytes in Java, plus additional ~4 GB memory for creating the String object, so, in total around 8GB of heap space. So, it is not a good design to read a large file ~2GB into a string for further processing.

Q2. What will be the output if you try to read a 2 GB file into a StringBuilder?

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SQLException handling – recoverable & irrecoverable scenarios

Q1. What is wrong with SQLException? A1. When a SQLException occurs, you do not necessarily know what went wrong. It could be a temporary failure that correct itself with time like a database deadlock or rebooting server OR a permanent fault like bad SQL or missing columns in a table…

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Top 5 Core Java Exceptions and best practices

#1: ConcurrentModificationException Getting a ConcurrentModificationException when trying to modify (i.e. adding or removing an item) a collection while iterating. The following code throws a ConcurrentModificationException.

To avoid ConcurrentModificationException in a single-threaded environment, you can remove the object that you are working on with the iterator.

To Avoid ConcurrentModificationException…

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