File infile = new File(""); Answer: Declare and initialize a File variable infile for the file with name
Scanner in = new Scanner(infile); Answer: Declare and initialize a Scanner variable in that reads from infile
String word = (); Answer: Declare and initialize a va...
File infile = new File("in.txt"); Answer: Declare and initialize a File variable infile for the file with
name in.txt
Scanner in = new Scanner(infile); Answer: Declare and initialize a Scanner variable in that reads from
infile
String word = in.next(); Answer: Declare and initialize a variable word with the first word from the
file.
in.close(); Answer: Close the scanner.
PrintWriter out = new PrintWriter("out.txt"); Answer: Declare and initialize a PrintWriter variable
out that writes to out.txt.
out.println("Hello"); Answer: Write a line consisting of the word Hello to out.txt.
out.close(); Answer: Close the writer.
B Answer: Which of the following is the correct way to create a Scanner object to read text from an
input file data.txt?
A) Scanner inputFile = new Scanner("data.txt");
B) File theFile = new File("data.txt"); Scanner inputFile = new Scanner(theFile);
C) Scanner inputFile = new Scanner("data.txt"); File theFile = new File(inputFile);
D) Scanner inputFile = new File("data.txt");
,D Answer: Which of the following is the correct way to create a PrintWriter object to write text to
an output file results.txt?
A) PrintWriter outputFile = new
PrintStream("results.txt");
B) PrintWriter outputFile = new
File("results.txt")
C) Scanner theFile = new Scanner("results.txt");
PrintWriter outputFile = new
PrintWriter (theFile);
D) PrintWriter outputFile = new
PrintWriter("results.txt");
D Answer: What happens when you supply the same name for the input and output files to the
Total program? Try it out if you are not sure.
A) The program reads all input from the file and then writes the formatted values and the total to the
file.
B) An exception is thrown in the PrintWriter construction
C) An exception is thrown in the call in.nextDouble()
D) The while loop is never entered
D Answer: What happens when you supply the name of a nonexistent input file to the Total
program? Try it out if you are not sure.
A) The program writes an empty output file and exits normally
,B) The program writes "Total: 0.00" to the output and exits normally
C) The statement File inputFile = new File(inputFileName); throws an exception
D) The statement Scanner in = new Scanner(inputFile); throws an exception
objects Answer: "Hello" and System.out are examples of _____.
methods Answer: length, substring, and println are examples of _____.
classes Answer: String, Student, and PrintStream are examples of _____.
String Answer: length and substring are methods of the _____ class, but println is not.
public interface Answer: The names and behavior of the methods of a class form the _____ _____
of the class.
encapsulation Answer: The user of a class only knows the public interface, not the implementation
details, of a class. This is called _____.
C Answer: Assuming that name is a String object, which of the following is a legal method call?
A) name.println();
B) name.nextInt();
C) name.charAt(0);
D) name.parseInt();
A Answer: Suppose you want to work with objects of the Student class. What do you need to know?
, A) The public interface of the class
B) The private implementation of the class
C) Both the public interface and the private implementation
D) Only the names of the method parameters
True Answer: True or False? System.out is an object.
False Answer: True or False? String is an object.
False Answer: True or False? The String class stores strings as arrays of characters.
True Answer: True or False? Suppose that a new version of Java is released, and that the Java
compiler changes the way that string objects store characters. If the string methods are updated
accordingly, then you won't need to change your code.
D Answer: What is the purpose of an object's instance variables?
A) To provide access to the data of an object
B) To create variables with public visibility
C) To store the data for all objects created by the same class
D) To store the data for a single instance of a class
1 Answer: 1 public class Counter
2{
3 private int value;
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