Java Variables Quiz

Which of the following is a valid way to declare a variable in Java?

• int number = 10;

• All of the above

• var number = 10;

• Integer number = 10;

What will be the output of the following code? public class Calculate { public static void main(String[] args) { int a; System.out.println(a); } }

• 0

• Compilation Error

• Runtime Error

• Undefined Behavior

Which of the following is true about variable names in Java?

• Variable names can start with a number

• Variable names can contain special characters like @ or #

• Variable names are case-sensitive

• Variable names can be a Java keyword

What is the default value of a boolean instance variable in Java?

• Compilation Error

• null

• false

• true

What will be the output of the following Java program? public class Main { static int x; public static void main(String[] args) { System.out.println(x); } }

• Runtime Error

• 0

• Compilation Error

• Undefined Behavior

What is the correct way to declare a constant variable in Java?

• const int MAX = 100;

• final int MAX = 100;

• int const MAX = 100;

• MAX = 100;

What will be the output of this code? public class Example { int num = 5; public static void main(String[] args) { Example obj = new Example(); System.out.println(obj.num); } }

• Undefined Behavior

• 5

• Compilation Error

• Runtime Error

Which of the following statements about var keyword is FALSE?

• var must be initialized at the time of declaration

• var is introduced in Java 8

• var can be used for instance variables

• var can be used for local variables

What will be the output of this Java program? public class Demo { public static void main(String[] args) { int x = 10; { int x = 20; System.out.println(x); } } }

• Compilation Error

• 10

• 20

• Runtime Error

Which of the following statements is correct?

• Static variables are shared among all objects of a class

• Local variables are automatically initialized

• Instance variables cannot be final

• A final variable can be reassigned