Java Language Fundamentals Flashcards

What is the result of compiling and running the following code? int x = 5; System.out.println(x++ + ++x);

Answer: 12

x++ returns 5 (then x becomes 6), ++x increments to 7 and returns 7, so 5+7=12.

Which of the following is a valid declaration of a multi-dimensional array in Java?

Answer: int[][] arr = new int[3][3];

int[][] arr = new int[3][3]; is the standard Java syntax for a 2D array declaration and initialization.

Which keyword is used to prevent a variable from being reassigned after initialization?

Answer: final

The 'final' keyword prevents reassignment of a variable once it has been initialized.

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

Answer: false

Instance variables of type boolean are automatically initialized to false if not explicitly set.

Which of the following correctly describes operator precedence between * and +?

Answer: * has higher precedence than +

Multiplication (*) has higher precedence than addition (+), so 2+3*4 evaluates to 14, not 20.

What does the following code print? String s = "Hello"; s.concat(" World"); System.out.println(s);

Answer: Hello

Strings are immutable in Java; concat() returns a new String but the original reference 's' is unchanged.

Which of the following is NOT a valid identifier in Java?

Answer: 2ndItem

Java identifiers cannot begin with a digit; '2ndItem' is invalid because it starts with '2'.