Difference Between final finally finalize with Real Time Examples

Difference between final finally finalize:

Difference between final finally finalize

final, finally, and finalize are all keywords in Java, but they have different meanings and uses. Here are the definitions and examples of each:

  1. final: final is a keyword used to indicate that a variable, method, or class cannot be changed after it has been initialized.

Example:

public final int NUMBER_OF_DAYS = 7; // once initialized, this value cannot be changed
  1. finally: finally is a keyword used in a try-catch-finally block to specify a block of code that will be executed regardless of whether an exception is thrown or not. This block is typically used to clean up resources or perform final actions.

Example:

try {
  // code that may throw an exception
} catch (Exception e) {
  // handle the exception
} finally {
  // code that will be executed regardless of whether an exception is thrown or not
  // e.g. closing a file or database connection
}
  1. finalize: finalize is a method that is called by the Java virtual machine when an object is no longer being used and is about to be garbage collected. This method can be used to perform final actions on the object before it is destroyed.

Example:

public class MyClass {
  @Override
  protected void finalize() throws Throwable {
    // code to perform final actions on this object before it is garbage collected
  }
}

In summary, final is used to indicate that a variable, method, or class cannot be changed after initialization, finally is used to specify a block of code that will be executed regardless of whether an exception is thrown or not, and finalize is a method that is called by the Java virtual machine when an object is about to be garbage collected.

final, finally finalize in java interview questions

Here are some interview questions related to the keywords final, finally, and finalize in Java:

  1. What is the difference between final, finally, and finalize in Java?
  2. What is the purpose of the final keyword in Java? Can you give an example?
  3. What is the purpose of the finally block in a try-catch-finally statement? Can you give an example?
  4. What is the purpose of the finalize method in Java? Can you give an example?
  5. Can a final variable be reassigned a new value? Why or why not?
  6. Is it possible to catch an exception thrown from a finally block? Why or why not?
  7. What is the difference between finalize and a destructor in other programming languages?
  8. Can the finalize method prevent an object from being garbage collected? Why or why not?
  9. Why is it a good practice to declare a variable as final in Java?
  10. How can you ensure that resources like file handles or network connections are properly closed in Java, even in the event of an exception?

What is the use of finally () method in Java?

The finally block in Java is used in combination with a try-catch block to ensure that a certain piece of code is always executed, whether an exception is thrown or not. The finally block contains code that will be executed regardless of whether an exception is thrown or not.

The purpose of the finally block is to release resources or perform any necessary cleanup operations that need to be done, even if an exception is thrown. For example, if you are reading from a file in a try block, you can close the file in the finally block, so that the file will be closed even if an exception is thrown while reading.

Here is an example of a try-catch-finally block:

try {
    // code that might throw an exception
} catch (Exception e) {
    // handle the exception
} finally {
    // code that will always be executed, regardless of whether an exception is thrown or not
    // e.g. closing a file or database connection
}

In this example, the try block contains code that might throw an exception. If an exception is thrown, the catch block will handle the exception. The finally block will always be executed, regardless of whether an exception is thrown or not, and can be used to release resources or perform cleanup operations.

final finally finalize in java interview questions with answers

  1. What is the difference between final, finally, and finalize in Java?

Answer:

  • final is a keyword used to indicate that a variable, method, or class cannot be changed after it has been initialized.
  • finally is a keyword used in a try-catch-finally block to specify a block of code that will be executed regardless of whether an exception is thrown or not.
  • finalize is a method that is called by the Java virtual machine when an object is no longer being used and is about to be garbage collected.
  1. What is the purpose of the final keyword in Java? Can you give an example?

Answer: The final keyword is used to indicate that a variable, method, or class cannot be changed after it has been initialized. This is useful for defining constants, or for preventing accidental modification of important code. Here is an example of a final variable:

public final int MAX_NUMBER_OF_THREADS = 10;

This variable cannot be reassigned a new value once it has been initialized.

  1. What is the purpose of the finally block in a try-catch-finally statement? Can you give an example?

Answer: The finally block is used to specify a block of code that will be executed regardless of whether an exception is thrown or not. This is useful for cleaning up resources or performing final actions. Here is an example:

try {
  // code that may throw an exception
} catch (Exception e) {
  // handle the exception
} finally {
  // code that will be executed regardless of whether an exception is thrown or not
  // e.g. closing a file or database connection
}
  1. What is the purpose of the finalize method in Java? Can you give an example?

Answer: The finalize method is called by the Java virtual machine when an object is no longer being used and is about to be garbage collected. This method can be used to perform final actions on the object before it is destroyed. Here is an example:

public class MyClass {
  @Override
  protected void finalize() throws Throwable {
    // code to perform final actions on this object before it is garbage collected
  }
}
  1. Can a final variable be reassigned a new value? Why or why not?

Answer: No, a final variable cannot be reassigned a new value once it has been initialized. This is because the final keyword indicates that the value is constant and cannot be changed.

  1. Is it possible to catch an exception thrown from a finally block? Why or why not?

Answer: No, it is not possible to catch an exception thrown from a finally block. This is because the finally block is always executed, regardless of whether an exception is thrown or not. Any exceptions thrown in the finally block will override any previous exceptions that were thrown.

  1. What is the difference between finalize and a destructor in other programming languages?

Answer: finalize in Java is similar to a destructor in other programming languages, in that it is used to perform final actions on an object before it is destroyed. However, there are some differences. For example, in C++, a destructor is called explicitly by the programmer, while finalize in Java is called automatically by the garbage collector.

  1. Can the finalize method prevent an object from being garbage collected? Why or why not?

Answer: Yes, the finalize method can prevent an object from being garbage collected, if it causes an exception to be thrown. This is because the garbage collector will not finalize an object that has an active finalize method.

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