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1Z0-809 · Question #47

Given the code fragment: public static void main (String[] args) throws IOException { BufferedReader bRcopy = null; try (BufferedReader bR = new BufferedReader (new FileReader ("employee.txt"))) {…

The correct answer is D. The code prints the content of the employee.txt file and throws an exception at line n3. Option D is correct because the try-with-resources block automatically closes bR when execution exits the try block - and since bRcopy holds a reference to the same underlying object, it too is closed. The file read and forEach print execute successfully before the block…

Question

Given the code fragment: public static void main (String[] args) throws IOException { BufferedReader bRcopy = null; try (BufferedReader bR = new BufferedReader (new FileReader ("employee.txt"))) { // line n1 bR.lines().forEach (c -> System.out.println(c)); bRcopy = bR; //line n2 } bRcopy.ready(); //line n3; } Assume that the ready method of the BufferedReader, when called on a closed BufferedReader, throws an exception, and employee.txt is accessible and contains valid text. What is the result?

Options

  • AA compilation error occurs at line n3.
  • BA compilation error occurs at line n1.
  • CA compilation error occurs at line n2.
  • DThe code prints the content of the employee.txt file and throws an exception at line n3.

How the community answered

(29 responses)
  • A
    3% (1)
  • B
    10% (3)
  • C
    14% (4)
  • D
    72% (21)

Explanation

Option D is correct because the try-with-resources block automatically closes bR when execution exits the try block - and since bRcopy holds a reference to the same underlying object, it too is closed. The file read and forEach print execute successfully before the block closes, so output is produced; then bRcopy.ready() at line n3 triggers the IOException described in the problem.

Lines n1, n2, and n3 all compile without error: BufferedReader implements AutoCloseable (valid for try-with-resources), assigning one BufferedReader reference to another is type-safe, and calling bRcopy.ready() is syntactically fine since the checked IOException is covered by the throws declaration on main. The distractors (A, B, C) all require a compilation error that doesn't exist.

Memory tip: Storing a try-with-resources variable in an outside reference does not escape the auto-close - think of try-with-resources as "close the object, not just the variable." Any alias pointing to the same resource is equally dead after the block ends.

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