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What will be the output of calling a method overridden in the child class?

  • It depends on how the method is called
  • It depends on the method's signature
  • The child class's method will always be called
  • The parent class's method will always be called
When a method is overridden in the child class, the version of the method in the child class is called when the method is invoked on an instance of the child class. This is known as method overriding and is a fundamental concept in object-oriented programming.
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In a multithreaded application where multiple threads are reading and writing to a shared User object, how would you ensure that the read and write operations are thread-safe?

  • Ensure that all threads run in a single thread by using a single-core CPU.
  • Implement a ReadWriteLock to control access to the User object.
  • Use synchronized methods for read and write operations on the User object.
  • Use the volatile keyword for the User object.
To ensure thread safety in a multithreaded application, you can use synchronized methods for read and write operations on the shared User object. This prevents multiple threads from accessing and modifying the object simultaneously, avoiding data corruption and race conditions. The other options do not provide effective thread safety mechanisms.
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The ______ method of the Lock interface is used to acquire the lock.

  • acquire()
  • lock()
  • tryLock()
  • unlock()
The lock() method of the Lock interface is used to acquire the lock. It blocks until the lock is available and then acquires it. The unlock() method is used to release the lock. The acquire() and tryLock() methods are not part of the standard Lock interface in Java.
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Consider a scenario where you have a large number of short-lived asynchronous tasks. Which type of ExecutorService would you consider using and why?

  • CachedThreadPoolExecutor: A thread pool that dynamically creates and recycles threads.
  • FixedThreadPoolExecutor: A fixed-size thread pool with a specific number of threads.
  • ScheduledThreadPoolExecutor: A thread pool for scheduling tasks at a fixed rate or delay.
  • SingleThreadPoolExecutor: A single-threaded ExecutorService.
In this scenario, the CachedThreadPoolExecutor is suitable. It dynamically adjusts the number of threads based on the workload, making it efficient for short-lived tasks. SingleThreadPoolExecutor and FixedThreadPoolExecutor have limitations for such cases, and ScheduledThreadPoolExecutor is designed for scheduling tasks, not managing short-lived tasks.
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The ________ interface is used to execute SQL stored procedures.

  • CallableStatement
  • Connection
  • PreparedStatement
  • Statement
In JDBC, the CallableStatement interface is used to execute SQL stored procedures. It allows you to call stored procedures that may take parameters and return values. Statement is used for executing regular SQL statements, Connection is used for establishing database connections, and PreparedStatement is used for executing parameterized SQL queries.
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The ________ data type in Java can store decimal numbers up to 15 decimal places.

  • BigDecimal
  • double
  • float
  • long
In Java, the BigDecimal data type is used to store decimal numbers with precision up to 15 decimal places. It is commonly used in financial and scientific applications where high precision is required. The float and double types have limited precision and are not suitable for this purpose.
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Externalizable interface extends ______ interface and adds two methods into it.

  • Cloneable
  • Externalization
  • ObjectInput/Output
  • Serializable
The Externalizable interface in Java extends the ObjectInput and ObjectOutput interfaces and adds two methods into it: writeExternal and readExternal. These methods are used for customized serialization of objects. The other options are not related to the Externalizable interface.
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In which version of Java were Lambda expressions introduced?

  • Java 6
  • Java 7
  • Java 8
  • Java 9
Lambda expressions were introduced in Java 8. They are a significant feature that simplifies the syntax for writing anonymous functions and enhances the readability and conciseness of code in Java.
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The ________ class represents a Uniform Resource Identifier and is designed to handle the complete URI syntax.

  • URI
  • URL
  • URN
  • UniformResource
The correct answer is "URI." In Java, the URI class is used to represent a Uniform Resource Identifier. It's designed to handle the complete URI syntax, including components like scheme, authority, path, query, and fragment. A URI is a broader concept that includes URLs (Uniform Resource Locators) and URNs (Uniform Resource Names).
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The ________ method of the ExecutorService interface is commonly used to submit a Callable task and returns a Future object.

  • execute
  • invokeAll
  • start
  • submit
In Java, the submit method of the ExecutorService interface is used to submit a Callable task and returns a Future object representing the result of the computation. This method is commonly used for asynchronous tasks that return results.
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