Interview Questions Answers in Core Java, Dot Net General, MySQL

Question { 639 }

Garbage collector thread is what kind of a thread?

Answer

It is a daemon thread.

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Question { 682 }

State the methods used during deserialization and serialization process.

Answer

ObjectInputStream.readObject Reads the file and deserializes the object.

ObjectOuputStream.writeObject Serialize the object and write the serialized object to a file.

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Question { 682 }

State the methods used during deserialization and serialization process.

Answer

ObjectInputStream.readObject Reads the file and deserializes the object.

ObjectOuputStream.writeObject Serialize the object and write the serialized object to a file.

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Question { 660 }

Explain the two different types of typecasting?

Answer

 Implicit: Defines the storing of values from smaller data types into larger data types, performed by the compiler only.
 Explicit: Defines the storing of values from larger data types into smaller data types that may result in information loss.

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Question { 662 }

Give an example program for Getter /read-only methods in JAVA

Answer

Read-only:
//A Read-only class in Java
public class Student{
//private data member
private String institute ="MKG";
//getter method for institute
public String getInstitute (){
return institute;
}
}

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Question { 633 }

Give an example for setter/ write-only methods

Answer

// A write-only class in Java
public class Student{
//private data member
private String institute;
//setter method for institute
public void setInstitute (String institute)
{ this.institute=institute;
}
}

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Question { 665 }

Explain the use of ‘this’ keyword in Java?

Answer

In Java, ‘this’ keyword represents a specific reference on the current object. There are multiple uses for this keyword for referring to the current class properties from a variable, constructors, methods, and more. You can also pass this as an argument within constructors or methods. You can also fetch this as a return value from the current class instance. You can also refer to this as a static context.

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Question { 948 }

Explain role-based security in .Net.

Answer

Role-based security in .Net is used to implement robust security measures based on the role assigned to the users in the organization. Users can then be authorized based on their roles in the organization. For instance, windows have role-based access such as administrators, users, and guests.

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Question { 800 }

How can a user get the current SQL version?

Answer

The syntax for getting the current version of MySQL:
SELECT VERSION ();

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Question { 800 }

How can a user get the current SQL version?

Answer

The syntax for getting the current version of MySQL:
SELECT VERSION ();

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Question { 643 }

Is there an object-oriented version of MySQL library functions?

Answer

Yes, MySQLi is the object-oriented version of MySQL, and it interfaces in PHP.

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Question { 643 }

What is the storage engine used for MySQL?

Answer

Storage tables are named as table types. The data is stored in the files using multiple techniques such as indexing, locking levels, capabilities, and functions.

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Question { 603 }

What is the use of ENUM in MySQL?

Answer

The use of ENUM will limit the values that can go into a table. For a case, a user can create a table giving specific month values and other month values would not enter into the table.

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Question { 681 }

How to create triggers in MySQL?

Answer

We can use the CREATE TRIGGER statement for creating a new trigger in MySQL.

SYNTAX:
CREATE TRIGGER trigger_name
(AFTER | BEFORE) (INSERT | UPDATE | DELETE)
ON table_name FOR EACH ROW
BEGIN
--variable declarations
--trigger code
END;

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Question { 584 }

What is the difference between the DELETE TABLE and TRUNCATE TABLE commands in MySQL?

Answer

DELETE TABLE is a logged operation, and every row deleted is logged. Therefore, the process is usually slow.
TRUNCATE TABLE also deletes rows in a table, but it will not log any of the rows deleted. The process is faster here in comparison. TRUNCATE TABLE can be rolled back and is functionally similar to the DELETE statement without a WHERE clause.

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mahindhan