Homework 1: Variables & Input / Output

Set Up

In this assignment you will be working with variables, and reading in user data.

To work on this homework, follow these steps:

  1. On Mac, open the Terminal program. On Windows, open the PowerShell program.

  2. Log into goldengate by using the ssh command from your personal laptop: ssh your-username@goldengate.cs.brynmawr.edu.

  3. Run these commands:

$ cd cs113
$ ls

If you see a homeworks directory, cd into it. Then, call mkdir hw1 to create your homework 1 directory. Finally, call cd hw1.

For each of the problems below, we will use the vim editor. You will need to create a java file for each problem. For example, for the first problem you will call vim Groceries.java.

Remember your vim commands: - vim Filename.java: creates a file named Filename.java - i: enter insert mode - esc: exit insert mode (you must exit insert mode in order to save and quit) - :wq: save the file and close vim

1. Groceries

Write a program called Groceries.java that computes the cost of groceries per week. Each person buys a different amount of groceries per week. You will ask a user to input

  1. how many times they bought groceries that week

  2. an estimate of how much each trip to the store costs

The program will then print out how much thaat person spends on groceries each week.

$ java Groceries.java
$ java Groceries
How many times do you go to the grocery store each week?
2
How much do you spend on each trip?
50.25
This week you spent $100.50 on groceries.

Your program should be able to handle numbers with decimal points.

2. Hotel Bill

Write a program called Bill that takes a user’s hotel room rate and outputs the cost of a 6% sales tax and 10.5% city tourism fee. The program should then output the total bill. Below is an example:

$ javac Bill.java
$ java Bill
Room rate
100
Total nights
3

Tax: $ 18.0
Tourism Fee: $ 31.5
Total: $ 349.50

3. Reading Code

For parts 3.1 and 3.2, put your answers in a text file. Call vim answers.txt to create a answers.txt file where you can put your answers.

3.1 Cats

Read the following program. What is the output of the program?

public class Cats {
   public static void main(String[] args) {
       String type = "tuxedo";
       int fish = 3;

       System.out.println("The "+type+" cat caught "+fish+" fish.");
   }
}

3.2 Mystery

public class Mystery1 {

    public static void main(String[] args) {

        String input = System.console().readLine()
        int value = Integer.parseInt(input);
        double fraction = value / 10
        System.out.println("The fraction is "+fraction);
    }
}

What is the error? How can we fix the problem?

Submitting

In a text file (call vim readme.txt) answer the following questions:

  1. How much time did you spend on the homework?

  2. What did you learn from the homework?

Finally, you need to copy your files from the server to your personal computer for submission.

Close your connection to goldengate (type exit), and then run the following command:

$ scp -r <username>@goldengate.cs.brynmawr.edu:/home/<username>/cs113/homeworks/hw1/ .

Make sure to replace <username> with your username. There is a space between hw1/ and .. scp is a command to secure-copy files from one server to another. In this case, from goldengate to your own machine.

Submit the following files to the assignment called HW01 on Gradescope.

  1. Groceries.java

  2. Bill.java

  3. answers.txt

  4. readme.txt