Java Basics

1/25 What does the 'transient' keyword signify in a Java class?
- The variable can be serialized
- The variable is thread-safe
- The variable cannot be serialized
- The variable is volatile
2/25 What is the output of the following Java code?
```
int[] array = {1, 2, 3};
System.out.println(array[3]);
```
- 3
- An ArrayIndexOutOfBoundsException is thrown
- null
- 0
3/25 What is the primary purpose of the 'super' keyword in Java?
- To call a method of the parent class
- To declare variables
- To create a new instance of the parent class
- To override a method in the child class
4/25 What is the default value of a static variable in Java?
- 0 or null, depending on the type
- 1
- undefined
- It does not have a default value
5/25 Which interface in Java is used for sorting and ordering?
- List
- Set
- Comparable
- Comparator
6/25 What does the 'static' keyword in Java signify?
- The method can be called without creating an instance of the class
- The method is immutable
- The method is synchronized
- The method returns a static value
7/25 In Java, what does the 'volatile' keyword do to a variable?
- It ensures the variable is synchronized across threads
- It makes the variable immutable
- It increases the variable's access speed
- It makes the variable transient
8/25 Which of the following is true about a 'final' class in Java?
- It can be extended by other classes
- It cannot be instantiated
- It can have final methods only
- It cannot be extended by other classes
9/25 Which method must be implemented in a class that implements the java.util.Comparator interface?
- compare()
- compareTo()
- equals()
- hashCode()
10/25 In Java, what is the purpose of the Collections.sort() method?
- To sort elements of a collection in descending order
- To randomly shuffle elements of a collection
- To sort elements of a collection in ascending order
- To reverse the order of elements in a collection
11/25 Which of the following is a checked exception in Java?
- NullPointerException
- ArrayIndexOutOfBoundsException
- IOException
- RuntimeException
12/25 In Java, what is a 'Lambda Expression'?
- A concise representation of an anonymous function that can be passed around
- A special type of exception
- A way to create a new thread
- An expression used for array manipulation
13/25 What does the 'synchronized' keyword ensure in a multi-threaded environment?
- Faster execution of threads
- That only a single thread can access the method or block at a time
- That multiple threads can execute the method concurrently
- That the method will always be executed by the main thread
14/25 In Java, which method you must override to use an object as a key in a HashMap?
- hashKey()
- mapKey()
- equals() and hashCode()
- getKey()
15/25 In Java, what is the effect of assigning a 'null' value to a reference variable?
- The reference variable is deleted
- It causes a compile-time error
- The reference variable points to no object
- It automatically initializes the object
16/25 How do you create a thread-safe singleton in Java?
- Using double-checked locking
- By making all methods synchronized
- By declaring all variables as volatile
- By using a static class
17/25 In Java, what is 'reflection' used for?
- To modify the behavior of a program at runtime
- To duplicate objects
- To analyze the performance of applications
- To convert primitive types into objects
18/25 What is a 'JavaBean'?
- A Java library for developing web applications
- A reusable software component that follows certain design conventions
- A type of Java variable
- A tool for managing Java packages
19/25 What does the 'final' keyword indicate when applied to a method in Java?
- The method can be overridden in a subclass
- The method cannot be overridden in a subclass
- The method will return a final value
- The method will be executed at the end of the program
20/25 What is the use of the 'implements' keyword in Java?
- To inherit from an abstract class
- To include an interface in a class
- To mark a method as mandatory to override
- To declare a class as abstract
21/25 What is the primary purpose of the 'try-with-resources' statement in Java?
- To execute a block of code multiple times
- To automatically close resources after execution
- To handle multiple exceptions in a single catch block
- To improve the performance of try-catch blocks
22/25 What is 'encapsulation' in Java?
- The technique of wrapping code and data together into a single unit
- A process of linking a method with an object
- A method of improving code execution time
- The division of a program into smaller parts
23/25 How is a 'static inner class' different from a 'non-static inner class' in Java?
- Static inner class can access static members of the outer class only
- Non-static inner class cannot access any members of the outer class
- Static inner class requires an instance of the outer class to exist
- Non-static inner class can exist independently of the outer class
24/25 In Java, which method would you use to compare two String objects for content equality?
- compareTo()
- equals()
- match()
- equalContent()
25/25 What is the advantage of using a 'PreparedStatement' in JDBC?
- Faster execution for repeated queries
- Allows execution of dynamic queries only
- Automatically closes database connections
- Improves the UI of the application
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Java Basics

1/25 What does the 'transient' keyword signify in a Java class?

2/25 What is the output of the following Java code?

3/25 What is the primary purpose of the 'super' keyword in Java?

4/25 What is the default value of a static variable in Java?

5/25 Which interface in Java is used for sorting and ordering?

6/25 What does the 'static' keyword in Java signify?

7/25 In Java, what does the 'volatile' keyword do to a variable?

8/25 Which of the following is true about a 'final' class in Java?

9/25 Which method must be implemented in a class that implements the java.util.Comparator interface?

10/25 In Java, what is the purpose of the Collections.sort() method?

11/25 Which of the following is a checked exception in Java?

12/25 In Java, what is a 'Lambda Expression'?

13/25 What does the 'synchronized' keyword ensure in a multi-threaded environment?

14/25 In Java, which method you must override to use an object as a key in a HashMap?

15/25 In Java, what is the effect of assigning a 'null' value to a reference variable?

16/25 How do you create a thread-safe singleton in Java?

17/25 In Java, what is 'reflection' used for?

18/25 What is a 'JavaBean'?

19/25 What does the 'final' keyword indicate when applied to a method in Java?

20/25 What is the use of the 'implements' keyword in Java?

21/25 What is the primary purpose of the 'try-with-resources' statement in Java?

22/25 What is 'encapsulation' in Java?

23/25 How is a 'static inner class' different from a 'non-static inner class' in Java?

24/25 In Java, which method would you use to compare two String objects for content equality?

25/25 What is the advantage of using a 'PreparedStatement' in JDBC?