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- Question
What is the difference between a constructor and a method?
- Correct Answer
- A constructor is a member function of a class that is used to create objects of that class It has the same name as the class itself, has no return type, and is invoked using the new operator We cannot invoke a constructor directly A method is an ordinary member function of a class It has its own name, a return type (which may be void), and is invoked using the dot operator
- 1. What are the steps required to execute a query in JDBC? Discuss
- 2. What is JDBC Driver ? Discuss
- 3. What is a class, member and local variable? Discuss
- 4. X implements Y, Z Arguments: 1. X should be class 2. Y, Z should be interfaces
Options- A. Only 1 is true
- B. Only 2 is true
- C. Both 1 and 2 are true
- D. None Discuss
- 5. public abstract class Shape { private int x; private int y; public abstract void draw(); public void setAnchor(int x, int y) { this.x = x; this.y = y; } } Which two classes use the Shape class correctly?
Options- A. public class Circle implements Shape { private int radius;
- B. public abstract class Circle extends Shape { private int radius; }
- C. public class Circle extends Shape { private int radius; public void draw();
- D. None Discuss
- 6. What is an abstract class? Discuss
- 7. How will you define an abstract class? Discuss
- 8. What is the difference between array and ArrayList ? Discuss
- 9. What is diamond problem? Discuss
- 10. What is the security mechanism used in java? Discuss
Technology problems
Search Results
Correct Answer: First we need to create an instance of a JDBC driver or load JDBC drivers, then we need to register this driver with DriverManager class Then we can open a connection By using this connection , we can create a statement object and this object will help us to execute the query
Correct Answer: The JDBC Driver provides vendor-specific implementations of the abstract classes provided by the JDBC API This driver is used to connect to the database
Correct Answer: Variables declared within a method are local variables Variables declared within the class are member variables Variables declared within the class with static modifier are class variables
Correct Answer: Both 1 and 2 are true
Explanation:
Both the statements are true
Correct Answer: public abstract class Circle extends Shape { private int radius; }
Explanation:
Only B is true
Correct Answer: An abstract class is an incomplete class An abstract class is defined with the keyword abstract We cannot create an object of the abstract class because it is not complete It sets a behavioral protocol for all its child classes
Correct Answer: An abstract class is defined with the keyword abstract Eg: public abstract class MyClass { }
Correct Answer: Array is collection of same data type Array size is fixed, It cannot be expanded But ArrayList is a growable collection of objectsArrayList is a part of Collections Framework and can work with only objects
Correct Answer: The diamond problem is an ambiguity that can occur when a class multiply inherits from two classes that both descend from a common super class
Correct Answer: Java uses sand box security model
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