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Java Basics

1/25 What is the use of the 'final' keyword in Java?
- To finalize object creation
- To create a constant variable or method
- To indicate the final class in a hierarchy
- To finalize variable assignments
2/25 Which interface in Java is used for sorting and ordering?
- List
- Set
- Comparable
- Comparator
3/25 What is the default size of a 'HashSet' in Java?
- 16
- 10
- 12
- 32
4/25 Which exception is thrown when trying to access an element with a key that does not exist in a HashMap?
- NullPointerException
- ArrayIndexOutOfBoundsException
- KeyNotFoundException
- NoSuchElementException
5/25 Which of these data types is used to represent a single character in Java?
- String
- char
- Character
- byte
6/25 How do you handle exceptions in Java?
- Using try-catch blocks
- By using the 'throws' keyword
- By using the 'extends' keyword
- By declaring them as static
7/25 What is the purpose of the 'package' statement in Java?
- To enhance the performance of the application
- To create a new thread
- To define a namespace for classes
- To import external libraries
8/25 Which method must be implemented in a class that implements the java.util.Comparator interface?
- compare()
- compareTo()
- equals()
- hashCode()
9/25 Which collection interface represents a key-value pair in Java?
- List
- Set
- Map
- Queue
10/25 Which Java feature allows runtime binding of method calls?
- Static Typing
- Dynamic Binding
- Method Overloading
- Method Overriding
11/25 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
12/25 Which method is used to compare two strings for equality in Java?
- compareTo()
- equals()
- equalsIgnoreCase()
- compare()
13/25 In Java, which method you must override to use an object as a key in a HashMap?
- hashKey()
- mapKey()
- equals() and hashCode()
- getKey()
14/25 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
15/25 What is the difference between 'static' and 'non-static' methods in Java?
- Static methods can be called without creating an instance of the class
- Non-static methods are always synchronized
- Static methods are faster
- Non-static methods can access any class variable
16/25 What does the 'throws' keyword do in Java?
- Automatically handles an exception
- Declares an exception which might be thrown
- Stops the propagation of an exception
- Increases the throw range of an exception
17/25 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
18/25 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
19/25 In Java, what is the default layout manager for the JFrame container?
- FlowLayout
- GridLayout
- BorderLayout
- CardLayout
20/25 Which method in the Object class is used to obtain a unique hash code for the object?
- uniqueCode()
- hashCode()
- identityHashCode()
- getObjectHash()
21/25 How can you achieve thread safety in Java?
- By using synchronized blocks or methods
- By avoiding the use of multiple threads
- By using the 'volatile' keyword
- By making all methods and variables private
22/25 What is 'JDBC' in Java?
- Java Database Connectivity, a standard API for database access
- Java Data Binding Code, a framework for binding data to UI elements
- Just-in-time Database Compiler, a tool for database optimization
- Java Deployment and Compilation, a deployment tool
23/25 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
24/25 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
25/25 In Java, what is the purpose of the 'enum' keyword?
- To define a new exception type
- To declare a collection of constants
- To create an enumeration of values for iteration
- To optimize memory usage in large applications
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