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Java Basics

1/25 Which of these is not a valid Java access modifier?
- public
- protected
- private
- friend
2/25 Which Java feature allows the method of a subclass to override the method of its superclass?
- Inheritance
- Encapsulation
- Polymorphism
- Abstraction
3/25 What is the purpose of the 'this' keyword in Java?
- To refer to the current class instance variable
- To create a new instance of a class
- To terminate the current method
- To invoke a method of the superclass
4/25 In Java, which of the following is a valid way to declare an array?
- int array[5];
- int[] array = new int[5];
- array = new int[5];
- int array[] = new int[5];
5/25 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
6/25 Which of these is an immutable class in Java?
- java.lang.StringBuilder
- java.lang.String
- java.lang.StringBuffer
- java.util.ArrayList
7/25 In Java, what is the difference between '==' and 'equals()'?
- '==' checks for value equality, 'equals()' checks for reference equality
- '==' checks for reference equality, 'equals()' checks for value equality
- There is no difference
- 'equals()' is used only for strings
8/25 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
9/25 What is 'autoboxing' in Java?
- Automatically converting a primitive type into its corresponding wrapper class
- The process of optimizing code automatically
- Creating an automatic backup of the code
- A feature for automatic memory management
10/25 How do you declare a constant variable in Java?
- Using the 'constant' keyword
- Using the 'static final' keywords
- Using the 'immutable' keyword
- Declaring without initialization
11/25 What is the role of the 'break' statement in a loop in Java?
- To skip the current iteration of the loop
- To pause the loop execution temporarily
- To terminate the loop immediately
- To continue loop execution indefinitely
12/25 Which of the following is a checked exception in Java?
- NullPointerException
- ArrayIndexOutOfBoundsException
- IOException
- RuntimeException
13/25 Which Java feature allows runtime binding of method calls?
- Static Typing
- Dynamic Binding
- Method Overloading
- Method Overriding
14/25 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
15/25 Which method is used to compare two strings for equality in Java?
- compareTo()
- equals()
- equalsIgnoreCase()
- compare()
16/25 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
17/25 What is the primary difference between 'StringBuffer' and 'StringBuilder' in Java?
- StringBuffer is mutable, while StringBuilder is immutable
- StringBuilder is faster as it is not synchronized
- StringBuffer can store characters, while StringBuilder cannot
- StringBuilder is thread-safe, while StringBuffer is not
18/25 Which of these is not a feature of Java?
- Multiple inheritance of classes
- Automatic garbage collection
- Platform independence
- Strong memory management
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 In Java, what is the default layout manager for the JFrame container?
- FlowLayout
- GridLayout
- BorderLayout
- CardLayout
21/25 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
22/25 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
23/25 What does the 'this' keyword refer to in Java?
- The current method
- The current instance of the class in which it is used
- A static context in the class
- The superclass of the current class
24/25 In Java, what is the default value of a boolean variable in a class?
- true
- false
- null
- 0
25/25 What is 'type casting' in Java?
- Changing a variable from one type to another
- A method of error handling
- A process of making a class adhere to a specific interface
- Assigning a new value to a variable
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