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31 to 35 java questions

31. What is a Java Bean?
A Java Bean is a software component that has been designed to be reusable in a variety of different environments.

32. What are checked exceptions?
Checked exception are those which the Java compilerforces you to catch. e.g. IOException are checked Exceptions.

33. What are runtime exceptions?
Runtime exceptions are those exceptions that are thrown at runtime because of either wrong input data or because of wrong business logic etc. These are not checked by the compiler at compile time.

34. What is the difference between error and an exception?
An error is an irrecoverable condition occurring at runtime. Such as OutOfMemory error. These JVM errors and you can not repair them at runtime. While exceptions are conditions that occur because of bad input etc. e.g. FileNotFoundException will be thrown if the specified file does not exist. Or a NullPointerException will take place if you try using a null reference. In most of the cases it is possible to recover from an exception (probably by giving user a feedback for entering proper values etc.).

35. What is the purpose of finalization?
The purpose of finalization is to give an unreachable object the opportunity to perform any cleanup processing before the object is garbage collected. For example, closing a opened file, closing a opened database Connection.

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