Week 1

1) What best defines a "programming language"?

  1. It allows us to control a computer.
  2. It allows us to make a calculation.
  3. It allows to execute a program.
  4. It allows us to express an algorithm.

2) Select the valid identifiers from the following list. State why each of the others is not valid.

  1. 123
  2. $50
  3. 50dollars
  4. abs
  5. hunter
  6. @60cents
  7. a_b
  8. #define

3) We learned about basic programs such as Hello World!
How can we modify this to print a whole message?

Let's print two lines:

4) Write a Java program that creates TWO integer variables to the values of your choice (e.g. 4 and 5, 12 and 10, etc.) and computes and prints the following:

5) Answer the following:

  1. What is the result of the following Java expression: 5 + 6 * 3 ?
  2. How does the order of operations affect the evaluation of the following expression: 4 + 5 * 2 - 3 ?
  3. Evaluate the following Java expression: 10 / 2 + 3 * 5 - 4
  4. What is the output of the following code snippet? 
    int a = 2 + 3 * 4 - 1;
System.out.println("Result: " + a);
  5. Rewrite the following expression using parentheses to explicitly define the order of operations: 8 - 2 * 4 / 2 + 3
  6. What is the value of the variable 'b' after executing the following code snippet? 
    int b = 10;
b += 2 * 3 - 1;

6) Trace the following program:

public static void main(String [] args) {
    int a, b, c, d, e, f, g;
    a = 10;
    b = 27;
    System.out.println("a is " + a + ", b is " + b);

    c = a + b;
    System.out.println("a+b is " + c);
    d = a - b;
    System.out.println("a-b is " + d);
    e = a+b*3;
    System.out.println("a+b*3 is " + e);
    f = b / 2;
    System.out.println("b/2 is " + f);
    g = b % 10;
    System.out.println("b%10 is " + g);
}

7) Write a Java program to print the area and perimeter of a rectangle.

8) Write a Java program to convert temperature from Fahrenheit to Celsius degrees.

Temperature in degrees Celsius (°C) = (Temperature in degrees Fahrenheit (°F) - 32) * 5/9

9) What will be printed by the following program?

public static void main(String [] args) {
      int w, x;
      double y;
  
      w = -9;
      x = Math.abs(w + 5);
      y = Math.sqrt(x);
  
      System.out.printf("%d %d %.2f%n", w,x,y);
}

10) Assuming that the variable x has already been declared and assigned a value, is the following assignment legal? If not why?

double sqrt = Math.sqrt(x);

11) Write a Java program that initializes the radius of a circle and computes and prints the circle's area and circumference (perimeter). (Limit each result to a precision of 3 decimal places)

12) Write a Java expression that would compute the following:

equation

Answers to Week 1 found here

Review

a) Write a statement that reads an integer value from standard input into val. Assume that val has already been declared as an int variable. Assume also that stdin is a variable that references a Scanner object associated with standard input.

b) Assume the availability of a class named Arithmetic that provides a static method, add, that accepts two int arguments and returns their sum.

Two int variables, euroSales and asiaSales, have already been declared and initialized. Another int variable, eurasiaSales, has already been declared.

Write a statement that calls add to compute the sum of euroSales and asiaSales and that stores this value in eurasiaSales.

c) Given the variable pricePerCase, write an expression corresponding to the price of a dozen cases.

e) Write a Java expression that would compute the following:

equation

Week 2

1) Write a Java program that computes the cost of traveling between two cities.

Prompt for and read in the name of each city (two separate prompts), the distance (in miles) between the two cities, and the cost of travel per mile.

Run the program with the following data:

Your output should look like:

Lab 1: One Guess Game

The goal of this exercise is to program a Guess My Number game. When it's finished, it should work like this:

equation

Submit both the .java and .txt file to EC Lab Submissions under Class Labs on Blackboard before next class. (This lab will count as part of your CodeLab grade)

2) Three business partners are forming a company whose name will be of the form "Name1, Name2, and Name3". However, they can't agree whose name should be first, second or last.

Help them out by writing code that reads in their three names and prints each possible combination exactly once, on a line by itself (that is, each possible combination is terminated with a newline character).

Assume that name1, name2, and name3 have already been declared and use them in your code. Assume also that stdin is a variable that references a Scanner object associated with standard input.

For example, if your code read in Larry, Curly, and Moe it would print out "Larry, Curly, and Moe", "Curly, Larry, and Moe", etc., each on a separate line.

(CodeLab: Chapter 3: Input and output > 3.2: The Scanner class > #20966)

3) Write a Java program that converts a total number of seconds to hours, minutes, and seconds.

It should:

  1. prompt the user for input
  2. read an integer from the keyboard
  3. calculate the result
  4. and use printf to display the output

For example:

"5000 seconds = 1 hours, 23 minutes, and 20 seconds".

(Hint: Use the modulus operator)

4) Write a Java program to prompt the user to enter their first and last name, then generate a random integer between 1000 - 9999 (inclusive) and write it to a file as follows:

'[last name]_[first_name]_Info.txt'

Then read from the newly created file and print out the contents (it should be the same as you just entered, plus the ID number)

Answers to Week 2 found here

Review

a) Two variables, num and cost have been declared and given values: num is an integer and cost is a double. Write a single statement that outputs num and cost to standard output. Print both values (num first, then cost), separated by a space on a single line that is terminated with a newline character. Do not output any thing else.

(CodeLab: Chapter 2: Variables and operators > 2.4: Printing variables > #20979)


Week 3

1) Write a Java program that prompts the user and reads in an integer and check whether it is even or odd.

Input Example:

Expected Output:

2) Write a Java statement to accomplish each of the following:

  1. set q equal to the square root of 15 if v is negative
  2. set h to 3 if count is a multiple of 10
  3. use the ternary operator to set i equal to 7 if x is not negative or 8 otherwise

3) Write a Java program that prompts for three numbers from the user and prints out the largest number of the three.

Input Example:

Expected Output:

4) Write an if/else statement that compares the double variable pH with 7.0 and makes the following assignments to the int variables neutral, base, and acid:

(CodeLab: Chapter 5: Conditionals and logic > 5.4: Chaining and nesting > #20622)

5) Write a Java program to find the number of days in a month from a particular year.

First, we need to prompt the user for the month and the year:

Input Example:

Remember:

Every year that is exactly divisible by four is a leap year, except for years that are exactly divisible by 100, but these centurial years are leap years if they are exactly divisible by 400

So to evaluate if whether or not it is a leap year, we need to check whether:

  1. It is evenly divisible by 100
  2. If it is divisible by 100, then it should also be divisible by 400
  3. Except this, all other years evenly divisible by 4 are leap years

Expected Output:

6) Write a Java program to check whether a person is eligible to vote or not using the switch statement.

This Java program checks whether a person is eligible to vote based on their age.

Lab 2: Basic Grade Calculator

The goal of this exercise is to program a simple Grade Calculator.

So if the prompts and input look like:

grades

The output file: "John_Doe_Grade.txt" should look like:

grades

Submit both the .java and .txt file to EC Lab Submissions under Class Labs on Blackboard before next class. (This lab will count as part of your CodeLab grade)

Answers to Week 3 found here

Review

a) Write a switch statement that tests the value of the char variable response and performs the following actions:

(CodeLab: Chapter 5: Conditionals and logic > switch > #20623)

b) HTTP is the protocol that governs communications between web servers and web clients (i.e. browsers). Part of the protocol includes a status code returned by the server to tell the browser the status of its most recent page request.

Some of the codes and their meanings are listed below:

Given an int variable status, write a switch statement that prints out, on a line by itself, the appropriate label from the above list based on status.

(CodeLab: Chapter 5: Conditionals and logic > switch > #20926)

Week 4

1) Write a Java program that will read in a start number and an end number from a user. Then, using a while loop show all the values from the start to the end number, (inclusive).

number series

2) Write a program that will read in numbers from the user and sum them up. If the value entered by the user is 0 the program loop ends and the average of all the values entered is shown.

average calculator

Answers to Week 4 found here

Review

a) Given int variables k and total that have already been declared, use a do/while loop to compute the sum of the squares of the first 50 counting numbers, and store this value in total.

Thus your code should put 1*1 + 2*2 + 3*3 +... + 49*49 + 50*50 into total.

Use no variables other than k and total.

(CodeLab: Chapter 7: Loops > 7.6: The do-while loop > #20684)

b) For the following program:

public static void main(String [] args) {
    int i = 10;
    while (i > 1) {
        System.out.println(i);
        if (i % 2 == 0) {
            i = i / 2;
        } else {
            i = i + 1;
        }
    }
}

What is the output of this program?

c) Write a Java program that prompts the user to enter the number whose factorial they wish to compute and then calculates the factorial of that number using a while loop.

The factorial of any number n:

Example: the factorial of 5 is represented as 5!

And, 5! = 5 * 4 * 3 * 2 * 1 = 120

Note: The value of 0! is 1, according to the convention for an empty product.

Week 5

1) Write Java code for each the following tasks:

  1. Create a for loop that prints all even numbers between 1 and 20 (inclusive)

  2. Create a for loop that prints all odd numbers between 30 and 50 (inclusive)

  3. Create a for loop that prints the first 10 positive integers in descending order

  4. Create a for loop that calculates and prints the sum of the first 15 multiples of 5

Answers to Week 5 found here

Exam 1 Review

a) For the following program(s), identify the error (compiler, run-time, or logical) AND correct the following code so it will do what is explained:

1. The following section of code is supposed to initialize two numbers x and y and compute their sum. 

int x = 5;
int y = "10"; 

int sum = x + y;

System.out.println("Sum: " + sum);

2. The following section of code is supposed to calculate the sum of the numbers 1 to n.

Scanner stdin = new Scanner(System.in);
int n = stdin.nextInt();
int sum;
for (int i = 1; i <= n; i++) {
    sum = 0; 
    sum = sum + i;
}

System.out.println("sum = " + sum);

b) Make a simple program which will do the following tasks.

In your program, x and y should be two variables that you declare and then assign a value to -- either read the values in or use assignment statements.

1. Using the logical operator && (and), construct an if statement which will do the following:

Print "they are both positive" if the two variables are both greater than zero

For example, if x is 10 and y is 7.

Otherwise print the words: "they are not both positive"

(for example, if x is 10 and y is -6; or it might be that x is 0 and y is -3)

2. Using the logical operator || (or), construct an if statement which will do the following:

Print "at least one is positive" is either one (or both) of the two variables is greater than zero

For example, if x is -10 and y is 7; or it might be that x is 10 and y is 3 (in this case both are positive).

Otherwise print the words: "neither one is positive" (for example, if x is 0 and y is -6)

3. Using the logical operator ! (not), construct an if statement which will do the following:

Print "it is not positive" if one (you can pick either one to work with) of the two variables is not greater than zero -- for example, if x is -10.

Otherwise print the words: "it is positive" -- for example, if x is 6. (actually, this case is really saying it is not not positive)

c) Write a complete Java program (starting from import statement(s)) that reads in (from the keyboard) the following information about a book:

Based on the genre number of the book, the program should determine the genre and recommended age group for the book according to the table below:

book catalog chart

After determining the genre and recommended age group, the program should display the book's ID, title, author, genre, and recommended age group.

(when Book ID is 98765, title is "Superfudge", author is "Judy Blume", genre (int) is 1)

Sample output:

Book ID: 98765
Title: Superfudge
Author: Judy Blume
Genre: Fiction
Recommended Age Group: 7+

Keep reading in books (use a loop) until the user enters a Book ID number of -1.

Answers to Exam 1 Review here

Review

a) Write a for loop that prints in ascending order all the positive integers less than or equal to 200 that are divisible by both 2 and 3, separated by spaces.

(CodeLab: Chapter 7: Loops > 7.5: The for statement > #20998)

Lab 3: Book Sorting Program

The goal of this exercise is to write a complete Java program that reads a list of books from a text file and categorizes them into separate genre files based on specific criteria

Write a complete Java program (starting from import statement(s)) that reads in from the text file "books.txt", the following information about a book:

And must create separate text files for each possible genre:

For each book entry, determine the genre, based on the genre number of the book, according to the table below:

lab 3 book catalog chart

Write the book details in the appropriate genre file each on one line using the following format:

Book ID: [Book ID]  Title: [Title]  Author: [Author]

The program should loop until all entries in the "books.txt" file are processed.

After running your program, you should have the following output files ("Fiction.txt", "NonFiction.txt", "SciFi.txt", "Mystery.txt", "Romance.txt") and verify that each file contains the correct book entries

Submit the source code (.java file) and the FIVE output .txt files to EC Lab Submissions under Class Labs on Blackboard before next class. (This lab will count as part of your CodeLab grade)

Week 8

1) Write a Java program that reads in the user's first and last name and then prints out their initials.

Sample Input:
Enter name: John Doe

Sample Output:
Initials: J.D.

2) Consider the following String:

String hannah = "Did Hannah see bees? Hannah did.";

  1. What is the value displayed by the expression hannah.length()?

  2. What is the value returned by the method call hannah.charAt(12)?

  3. Write an expression that refers to the letter b in the String referred to by hannah.

3) Write a Java program to decode the following message:

Iqqf\"Lqd#\"[qw\"hkiwtgf\"kv\"qwv#

Each character in the original message has been shifted forward by 2. To decode this message we will have to shift each character down by 2.

What does the message say after it is decoded?

4) What is printed by the following sections of code? 

  1. String source = "ID is 12-AB-1X ";
int pos = source.indexOf('-'); 
int pos1 = source.indexOf(' ',pos+1); 
String str1 = source.substring(pos+1,pos1);
System.out.println(str1);
  2. source = "from Denver,CO.";
int pos2 = source.lastIndexOf(',');
int pos3 = source.lastIndexOf(' ',pos2);
String str2 = source.substring(pos3+1,pos2);
System.out.println(source.substring(pos3+1,pos2));
  3. System.out.println(str1.compareTo(str2)>0);

5) A String variable sentence consists of words separated by single spaces.

Write the Java code needed to print the number of words that start with an upper case letter.

So for "The deed is done", your code would print 1 but for "The name is Bond, JAMES Bond", your code would print 4.

6) Write a Java Program that prompts the user to enter a String and counts the number of vowels (a, e, i, o, u) in the String. Print out the total count to the console.

Sample Input:
Enter a String: Hello World

Sample Output:
Number of vowels: 3

Answers to Week 8 found here

Review

a) Write a Java Program that prompts the user to enter a String and checks if the String is a palindrome (reads the same forward and backward). Print out a message to the console indicating whether the String is a palindrome or not.

Sample Input:
Enter a String: Wow

Sample Output:
String reversed: woW
This String is a palindrome.

b) Using the text file: Week9Emails.txt, write a Java program that reads in the data (first name, last name, email address) from the text file, extract the domain names from the email addresses, and display a unique list of domain names on the console.

Sample Output:

Unique Domain Names:

gmail.com
yahoo.com
hotmail.com
outlook.com
aol.com

Week 9

1) Given the String variables name1 and name2, write a fragment of code that assigns the larger of the two to the variable first (assume that all three are already declared and that name1 and name2 have been assigned values).

(NOTE: "larger" here means alphabetically larger, not "longer". Thus, "mouse" is larger than "elephant" because "mouse" comes later in the dictionary than "elephant"!)

(CodeLab: Chapter 9: Strings and things > 9.6: String comparison > #20602)

2) Consider this data sequence: "fish bird reptile reptile bird bird bird mammal fish".

Let's define a SINGLETON to be a data element that is not repeated immediately before or after itself in the sequence. So, here there are four SINGLETONs (the first appearance of "fish", the first appearance of "bird", "mammal", and the second appearance of "fish").

Write some code that uses a loop to read a sequence of words, terminated by the "xxxxx". The code assigns to the variable n the number of SINGLETONs that were read.

For example: in the above data sequence it would assign 4 to n. Assume that n has already been declared. but not initialized. Assume that there will be at least one word before the terminating "xxxxx". ASSUME the availability of a variable, stdin, that references a Scanner object associated with standard input.

(CodeLab: Chapter 9: Strings and things > 9.6: String comparison > #21009)

Answers to Week 9 found here

Week 10

1) Write a void method called "printMessage()" that takes a String parameter and simply prints out the message to the console.

2) Create a void method called "calculateArea()" that takes two double parameters (length and width) and calculates the area of a rectangle using the formula: area = length * width. Print out the result to the console.

3) Write a Java method called "calcAverage()" that takes no arguments, prompts the user for three numbers (double) and then prints out the average of the three numbers with one decimal place.

Sample Input:
Input the first number: 25
Input the second number: 45
Input the third number: 65

Sample Output:
The average value is 45.0

4) Write a void method called "printPattern()" that takes an int parameter and prints a pattern of asterisks to the console.

For example, if the parameter is 5, the output should be:

5) Write a complete Java program that has the following:

Answers to Week 10 found here

Week 11

1) What will be printed by the following: 

public static void main(String [] args){
    int a, b, c;
            
    a = 1;
    b = 8;
    c = method(a, b);
    System.out.printf("%d  %d  %d\n", a, b, c);
    a = method(b, a);
    System.out.printf("%d  %d  %d\n", a, b, c);
}
        
public static int method(int b, int a){
    int d;
            
    d = a * b - b * b;
    return d + b;
}

2) Identify the following items in the program of Question 1:

  1. method header/signature
  2. method invocation
  3. method definition

3) Write a method biggest() that receives three int parameters. It will determine which value is the largest and return that value to the calling method.

4) Use the following formulas to write THREE overloaded calcPerimeter() methods, one for each shape. Each method should take the necessary parameters and return the perimeter as a double.

formulas

5) Write a complete Java program that prompts the user input to a String (can be an entire sentence) and count the occurrences of each letter.

This program should use a for loop to loop through the letters a - z (lowercase) and call a method countOccurences() that takes two parameters: the String and a particular character to search for and return how many times that letter is found within the String.

The main method should then print out this number to the console for each individual letter in the String.

For example:

Sample Input:

Enter String: Hello World

Sample Output:

d appears 1 times
e appears 1 times
h appears 1 times
l appears 3 times
o appears 2 times
r appears 1 times
w appears 1 times

6) Write a method named isDivisible() that takes two double parameters, n and m, and that returns true if n is divisible by m, and false otherwise.

7) If you are given three sticks, you may or may not be able to arrange them in a triangle. For example, if one of the sticks is 12 inches long and the other two are one inch long, you will not be able to get the short sticks to meet in the middle. For any three lengths, there is a simple test to see if it is possible to form a triangle:

If any of the three lengths is greater than the sum of the other two, you cannot form a triangle.

Write a method named isTriangle() that takes three integers as arguments and returns either true or false, depending on whether you can or cannot form a triangle from sticks with the given lengths. (Remember to also check that all the sides are positive!)

8) What is the output of the following program?

public static void main(String [] args) {
  boolean flag1 = isHoopy(202);
  boolean flag2 = isFrabjuous(202);
  System.out.println(flag1);
  System.out.println(flag2);
  if (flag1 && flag2) {
    System.out.println("ping!");
  }
  if (flag1 || flag2) {
    System.out.println("pong!");
  }
}
        
public static boolean isHoopy(int x) {
  boolean hoopyFlag;
  if (x % 2 == 0) {
    hoopyFlag = true;
  } else {
    hoopyFlag = false;
  }
  return hoopyFlag;
}
        
public static boolean isFrabjuous(int x) {
  boolean frabjuousFlag;
  if (x > 0) {
    frabjuousFlag = true;
  } else {
    frabjuousFlag = false;
  }
  return frabjuousFlag;
}

9) Use the following formulas to write a Java program that has three methods:

sphere dimensions

The main method should print out the volume, surface area, and whether or not the sphere is large.

Lab 4: Processing Bowling Scores

The goal of this lab is to write a complete Java program to do the following:

The main program reads in a series of three bowling scores: score1, score2, and score3 from a file ("scores.txt"), then calls a series of methods to process and print these scores: follow instructions found here

Submit the Java source code file (e.g., BowlingScores.java) and the program-generated output file (e.g., results.txt) file to EC Lab Submissions under Class Labs on Blackboard before next class. (This lab will count as part of your CodeLab grade)

Answers to Week 11 found here

Week 12

1) What is the output of the following program?

public static void main(String [] args) {
    int [] intArr = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
    for (int i = 0; i < intArr.length; i += 3) {
        System.out.println("Value: " + intArr[i]);
    }
}

2) What is the output of the following program?

public static void main(String [] args) {
    int [] intArr = {1, 2, 3, 4, 5};
    double [] dblArr = {0.5, 1, 1.5, 2, 2.5};
    for (int i = 0; i < intArr.length; i++) {
        dblArr[i] = dblArr[i] * intArr[i];
    }

    for (int i = 0; i < intArr.length; i++) {
        System.out.println(intArr[i] + " : " + dblArr[i]);
    }
}

3) Write a complete Java program that generates 20 random integers (between 1-100) and stores them in an array.

Then, use methods to count how many even, odd, or multiple of 5 appear in the set. (Hint: write a method for each specific criteria)

Print the entire array to the console along with how many numbers fit each specified criteria.

Sample Output:

Generated random numbers:
{39, 87, 36, 57, 9, 29, 2, 39, 14, 35, 84, 74, 29, 69, 94, 89, 89, 54, 94, 42}

Even numbers count: 9
Odd numbers count: 11
Multiples of 5 count: 1

4) An array of ints, arr, has been declared and initialized. Write the statements needed to reverse the elements in the array.

So, if the elements were originally 5, 13, 4, 97 then after your code executes they would be 97, 4, 13, 5.

(CodeLab: Chapter 8: Arrays > 8.6: Array traversal > #20767)