Java Programming Quiz 1

What is the purpose of a constructor in Java?

• To destroy an object

• To initialize an object

• To define a method

• To create a static variable

Which keyword is used to create an instance of a class?

• class

• new

• this

• static

Can a class have multiple constructors?

• No, only one constructor is allowed

• Yes, with different parameter lists

• Yes, but only with the same parameters

• Only if the class is static

Why are Strings immutable in Java?

• To improve performance

• To ensure security and thread safety

• To allow modification of String objects

• To reduce memory usage

What is the output of the following code? String s1 = "Hello"; String s2 = "Hello"; System.out.println(s1 == s2);

• false

• true

• Compilation error

• Runtime error

Which class is thread-safe for String manipulation?

• String

• StringBuilder

• StringBuffer

• None of the above

What does the this keyword refer to in Java?

• The class itself

• The current object

• A static method

• The parent class

Which of the following is a valid use of the this keyword?

• To call a static method

• To differentiate between instance and local variables

• To initialize a static variable

• To declare a class

Can the this keyword be used in a static method?

• Yes, to refer to the class

• No, it requires an instance

• Yes, but only for static variables

• Only in nested classes

What is true about a static method?

• It can only access instance variables

• It belongs to the class, not an instance

• It cannot be called without an object

• It cannot be overridden