| What is an Exception in Java? |
| What are the Exception Handling Keywords in Java? |
| Explain Java Exception Hierarchy? |
| What are the important methods of Java Exception Class? |
| Explain Java 7 ARM Feature and multi-catch block? |
| What is the difference between Checked and Unchecked Exceptions in Java? |
| What is the difference between the throw and throws keyword in Java? |
| How to write custom exceptions in Java? |
| What are different scenarios causing “Exception in thread main”? |
| What is the difference between final, finally, and finalize in Java? |
| What happens when an exception is thrown by the main method? |
| Can we have an empty catch block? |
| What is NullPointerException? |
| What is ArrayIndexOutOfBoundsException? |
| What is NumberFormatException? |
| How the exceptions are handled in java? OR Explain exception handling mechanism in java? |
| What is try block? |
| What is catch block? |
| What is finally block? |
| What is an exception? |
| What is the difference between error and exception in java? |
| What is unreachable catch block error? |
| What are run time exceptions in java. Give example? |
| What is OutOfMemoryError in java? |
| what are checked and unchecked exceptions in java? |
| What is the difference between ClassNotFoundException and NoClassDefFoundError in java? |
| What is Re-throwing an exception in java? |
| What is the use of throws keyword in java? |
| What is the difference between final, finally and finalize in java? |
| What is ClassCastException in java? |
| What is the difference between throw, throws and throwable in java? |
| What is StackOverflowError in java? |
| What are chained exceptions in java? |
| What are the legal combinations of try, catch and finally blocks? |
| What is the use of printStackTrace() method? |
| What is ClassNotFoundException? |
| What is SQLException? |
| What is IOException |
| Explain the hierarchy of exceptions in java? |
| Why it is always recommended that clean up operations like closing the DB resources to keep inside a finally block? |
| Which class is the super class for all types of errors and exceptions in java? |
| How the exceptions are handled in java? OR Explain exception handling mechanism in java? |
| How do you create customized exceptions in java? |
| Can we keep other statements in between try, catch and finally blocks? |
| Can we write only try block without catch and finally blocks? |
| Can we keep the statements after finally block If the control is returning from the finally block itself? |
| Can we throw an exception manually? If yes, how? |
| Can we override a super class method which is throwing an unchecked exception with checked exception in the sub class? |
| Does finally block get executed If either try or catch blocks are returning the control? |
| Give some examples to checked exceptions? |
| Give some examples to unchecked exceptions? |
- It is one of the powerful mechanism to handle the runtime errors
- The java.lang.Throwable class is the root class of Java Exception hierarchy which is inherited by two subclasses: Exception and Error.
- Checked Exception
- The classes which directly inherit Throwable class except RuntimeException and Error are known as checked exceptions
- e.g. IOException, SQLException etc. Checked exceptions are checked at compile-time.
- Unchecked Exception
- The classes which inherit RuntimeException are known as unchecked exceptions
- e.g. ArithmeticException, NullPointerException, ArrayIndexOutOfBoundsException etc.
- Unchecked exceptions are not checked at compile-time, but they are checked at runtime.
- Error - It is irrecoverable e.g. OutOfMemoryError, VirtualMachineError, AssertionError etc.
- try - It is used to specify a block where we should place exception code. The try block must be followed by either catch or finally. It means, we can't use try block alone.
- catch - It is used to handle the exception. It must be preceded by try block which means we can't use catch block alone. It can be followed by finally block later.
- finally - It is used to execute the important code of the program. It is executed whether an exception is handled or not.
- throw - It is used to throw an exception.
- throws - It is used to declare exceptions. It doesn't throw an exception. It specifies that there may occur an exception in the method. It is always used with method signature.
Example
- ArithmeticException - It is thrown when an exceptional condition has occurred in an arithmetic operation.
- ArrayIndexOutOfBoundsException - It is 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.
- ClassNotFoundException - This Exception is raised when we try to access a class whose definition is not found
- FileNotFoundException - This Exception is raised when a file is not accessible or does not open.
- IOException - It is thrown when an input-output operation failed or interrupted
- InterruptedException - It is thrown when a thread is waiting , sleeping , or doing some processing , and it is interrupted.
- NoSuchFieldException - It is thrown when a class does not contain the field (or variable) specified
- NoSuchMethodException - It is thrown when accessing a method which is not found.
- NullPointerException - This exception is raised when referring to the members of a null object. Null represents nothing
- NumberFormatException - This exception is raised when a method could not convert a string into a numeric format.
- RuntimeException- This represents any exception which occurs during runtime.
- StringIndexOutOfBoundsException - It is thrown by String class methods to indicate that an index is either negative than the size of the string
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