A201/A597 Exam 1 sample questions

Given the following declarations:

int quantity = 5;
double unitCost = 0.65;
String drink = "pepsi";

For each expression in the following table, indicate its value and the type of the value.

Expression	Value	Type
`Numeric.round(quantity * unitCost)`
`("diet " + drink).length()`
`drink.substring(1, 4).toUpperCase()`
`drink.equals("coke")`
`quantity + 10 + ""`
`(10 <= quantity) \|\| ((quantity` % `2) == 0)`

Each of the following program fragments was written twenty minutes before it was due to be turned in, and as a result contains one major error that either prevents it from running, or produces the wrong answer. Correct this error by rewriting or inserting one or more lines.

String areaCode, phoneNumber;

System.out.print("Enter your complete telephone number xxx-xxx-xxxx: ");
phoneNumber = Console.in.readLine();

phoneNumber.substring(0, 3) = areaCode;  // ERROR!

System.out.println("You live in area code " + areaCode + ".");

int gallons;
double mpg, distance;

distance = gallons * mpg;  // ERROR!
gallons = 148;
mpg = 21;

System.out.println("You can travel " + distance + " miles on " +
                   gallons + " gallons of gasoline.");

String name;

System.out.print("Enter your name: ");
Console.in.readLine();   // ERROR!

System.out.println("Your name starts with " + name.substring(0, 1));

int jellyDonuts, glazedDonuts;  // ERROR!
double jellyPrice = 0.45, glazedPrice = 0.35, totalCost;

System.out.print("How many jelly donuts do you want? ");
jellyDonuts = Console.in.readDouble();
System.out.print("How many glazed donuts do you want? ");
glazedDonuts = Console.in.readDouble();

totalCost = jellyDonuts * jellyPrice + glazedDonuts * glazedPrice;

String name; String letter;

name = "Dorothy";
letter = name.substring(length() - 1, length());  // ERROR!

System.out.println("This name ends with: " + letter);

Complete the following Java application which prompts the user for a word with an odd number of letters, and then prints the middle letter of the word. Here is a sample run. The user input is in italics.
Enter an odd-length word: chicken
The letter c is in the middle.
Do not worry about error checking the input. That is, do not bother to verify that the length of the word the user types is indeed odd. Here is the program that you are to complete.
```
public class MiddleLetter {
  public static void main(String[] args) {
```
```
  }
}
```

The user runs a program containing the following fragment and then types 3 8 at the prompt. What exactly is printed by the output statements?

int x, y;
System.out.print("Enter two integers: ");
x = Console.in.readInt();
y = Console.in.readInt();
x = 2 * x;
y = y - 1;
System.out.println("x = " + x + ", y = " + y);
y = 5;
x = y;
y = y - 1;
System.out.println("x = " + x + ", y = " + y);

What is printed by the following program fragment?

Time dinnerTime, examStart, examEnd;
dinnerTime = new Time(1998, 2, 18, 18, 0, 0);  // Feb 18, 1998 at 6 pm
examStart = new Time(1998, 2, 18, 19, 0, 0);   // Feb 18, 1998 at 7 pm
examEnd = examStart;

examEnd.addSeconds(2 * 60 * 60);

System.out.println(examStart.secondsFrom(examEnd));
System.out.println(dinnerTime.getHours() - examStart.getHours());
System.out.println(examEnd.getHours() - dinnerTime.getHours());

What is printed by the following code fragment?

int west = 1, language = 2;
if (west == 1) {
   if (language != 2)
      System.out.print("Auf Wiedersehen ");
   else
      System.out.print("Adios ");
   }
else
   System.out.print("Sayonara ");

Complete the following program which determines how many days a certain month has. Model your code on the following algorithm:
- Prompt the user for two integers: a month in the range 1 to 12, inclusive, and a year after 1970.
- Create a Time object for the first day of the next month. If the month is 12, corresponding to December, then be sure to create an object for January of the following year. Note: You must use an if statement.
- Subtract one day's worth of seconds to change the object so that it represents the last day of the month that the user entered. Hint: Use the addSeconds method with a negative value.
- Access and print the day field of the modified object.
You do not have to verify that the user input is in the expected range. Here is the program that you are to complete.
```
public class DaysInMonth {
  public static void main(String[] args) {
    int month, year;
    System.out.print("Enter a month number (1-12): ");
    month = Console.in.readInt();
    // You fill in the rest of the code that is needed...
```
```
  }
}
```