Download Exam 2 Answers

CSC202 Exam 2
Name: _________________________
Questions 1 – 12 are worth 5 points each.
1. What is wrong with the following program?
public class q1
{
public static void main(String[] args)
{
int i = 1;
while (i != 10)
{
System.out.println(i);
i = i + 2;
}
}
}
Infinite loop.
2. What is wrong with the following program?
public class q2
{
public static void main(String[] args)
{
int i = 10;
double j = 25.5;
methodA(i, j);
}
public static void methodB(int a, double b)
{
System.out.println(a);
System.out.println(b);
}
}
cannot find symbol
symbol : method methodA(int,double)
3. What is wrong with the following program?
public class q3
{
public static void main(String[] args)
{
int j;
j = method1();
System.out.println(j);
}
public static double method1()
{
double x = 2.3;
return x;
}
}
possible loss of precision found
required: int j = method1();
: double
4. When run, what will the following program output?
public class q4
{
public static void main(String[] args)
{
int i;
for (i = 10; i <= 20; i += 2)
{
System.out.println(i);
}
}
}
10
12
14
16
18
20
2
5. When run, what will the following program output?
public class q5
{
public static void main(String[] args)
{
int i = 0;
while (i <= 10)
{
System.out.println(i);
i = i + 5;
}
}
}
0
5
10
6. When run, what will the following program output?
public class q6
{
public static void main(String[] args)
{
int i = 10;
while (i > 100)
{
System.out.println(i);
}
System.out.println("Done");
}
}
Done
3
7. When run, what will the following program output?
public class q7
{
public static void main(String[] args)
{
int i, j;
for (i = 1; i <= 3; i++)
{
for (j = 1; j <= 2; j++)
{
System.out.print("Y");
}
System.out.println();
}
}
}
YY
YY
YY
8. When run, what will the following program output?
public class q8
{
public static void main(String[] args)
{
int i;
for (i = 1; i <= 3; i++)
{
methodA();
}
}
public static void methodA()
{
System.out.println("B");
}
}
B
B
B
4
9. When run, what will the following program output?
public class q9
{
public static void main(String[] args)
{
methodA();
methodB();
methodC();
}
public static void methodA()
{
System.out.println("A");
methodB();
System.out.println("A");
}
public static void methodB()
{
System.out.println("B");
methodC();
System.out.println("B");
}
public static void methodC()
{
System.out.println("C");
}
}
A
B
C
B
A
B
C
B
C
5
10. When run, what will the following program output?
public class q10
{
public static void main(String[] args)
{
System.out.println(method1("Joe"));
System.out.println(method1("Jane"));
}
public static int method1(String a)
{
if (a.equals("Joe"))
return 1;
else
return 0;
}
}
1
0
11. When run, what will the following program output?
public class q11
{
public static void main(String[] args)
{
int s = 0;
int i;
for (i = 1; i <= 5; i++)
{
s += i;
}
System.out.println(s);
}
}
15
6
12. In the following code, what values could be read into number to terminate the while loop?
Scanner keyboard = new Scanner(System.in);
System.out.print("Enter a number: ");
int number = keyboard.nextInt();
while (number < 0 || number > 100)
{
System.out.print("Enter another number:
number = keyboard.nextInt();
}
Any number between 0 and 100, inclusive.
7
");
13. Assuming that the file named data.txt exists and contains a series of numbers (1 per line),
write a program that will ask the user to input a number, and then print how many times that
number is in the file. (20 points).
import java.io.*;
import java.util.Scanner;
public class q13
{
public static void main(String[] args) throws IOException
{
File myFile = new File("data.txt");
Scanner inputFile = new Scanner(myFile);
Scanner keyboard = new Scanner(System.in);
int count = 0;
int choice;
int number;
System.out.print("Enter a number: ");
choice = keyboard.nextInt();
while (inputFile.hasNext())
{
number = inputFile.nextInt();
if (choice == number)
{
count++;
}
}
System.out.println(choice + " appears " + count
+ " times.");
}
}
8
14. Write a program that will randomly print one of four possible messages. (20 points)
import java.util.Random;
public class q14
{
public static void main(String[] args)
{
Random generator = new Random();
int choice = generator.nextInt(4);
switch (choice)
{
case 0:
System.out.println("message
break;
case 1:
System.out.println("message
break;
case 2:
System.out.println("message
break;
case 3:
System.out.println("message
break;
}
}
}
9
1");
2");
3");
4");