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Ans. Collections class is a utility class having static methods for doing operations on objects of classes which implement the Collection interface. For example, Collections has methods for finding the max element in a Collection.
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Ans. MVC is a Design Pattern that facilititates loose coupling by segregating responsibilities in a Web application
1. Controller receives the requests and handles overall control of the request
2. Model holds majority of the Business logic, and
3. View comprise of the view objects and GUI component
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Ans. String is immutable in java and stored in String pool. Once it's created it stays in the pool until unless garbage collected, so even though we are done with password it's available in memory for longer duration and there is no way to avoid it. It's a security risk because anyone having access to memory dump can find the password as clear text.
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Ans. If id doesnt exist in the DB load throws an exception whereas get returns null in that case.get makes the call to DB immediately whereas load makes the call to proxy.
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Ans. Abstract classes can have both abstract methods ( method declarations ) as well as concrete methods ( inherited to the derived classes ) whereas Interfaces can only have abstract methods ( method declarations ).
A class can extend single abstract class whereas it can implement multiple interfaces.
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Q39. Which access specifiers can be used with top level class ? a. public or default b. public or private c. public or protected d. protected or default
Ans. The goal of a synchronised block is to achieve mutual exclusion i.e at one time, the segment of the code should be executed by single thread only and hence the lock needs to be retrieved before executing the segment and then released.
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Which of the following class creates mutable objects ?
