Lab 1

Introduction to Java Programming

1. Compulsory (1p)
Write a Java application that implements the following operations:

• Display on the screen the message "Hello World!". Run the application. If it works, go to step 2 :)
• Define an array of strings languages, containing {"C", "C++", "C#", "Python", "Go", "Rust", "JavaScript", "PHP", "Swift", "Java"}
• Generate a random integer n: int n = (int) (Math.random() * 1_000_000);
• Compute the result obtained after performing the following calculations:

    multiply n by 3;
    add the binary number 10101 to the result;
    add the hexadecimal number FF to the result;
    multiply the result by 6;
  

• Compute the sum of the digits in the result obtained in the previous step. This is the new result. While the new result has more than one digit, continue to sum the digits of the result.
• Display on the screen the message: "Willy-nilly, this semester I will learn " + languages[result].

2. Homework (2p)

• A grayscale image can be represented using a 2D matrix, each cell containing a value between 0=black and 255=white. Consider that width=height=n.
  • Create the image of a dark rectangle, on a white background.
  • Create the image of a white circle, on a dark background.
• Implement a method that builds a string representation of the matrix, at your own choice. Display on the screen the generated matrix. Use Unicode characters to create a "pretty" representation of the matrix.
• For larger values of n, display the running time of the application in nanoseconds or milliseconds (do not display the matrix!). For what value of n you get an OutOfMemoryError? Adjust the JVM Heap Space using the VM options, such as -Xms4G -Xmx4G.
  
• Launch the application from the command line, for example: java Matrix2D 100 circle.

3. Advanced (2p)

• Write an algorithm that, given a matrix containing a geometric shape, determines the bounding box of the shape.
• Assume the shape may be irregular, and determine its boundary.

• The lab assignments are intentionally not very precise. Students are encouraged to customize their implementations as they wish, and creativity is appreciated.
• Create a new project for each laboratory. In a project, create at least one package. Create classes as necessary, do not use the same class for unrelated tasks. Each class must contain the name(s) of the author(s) as a comment.
• Please consult the API documentation to learn more information about the classes and methods used!
• Write code faster using keyboard shortcuts.

Resources

• Slides
• Download JDK
• Download Netbeans or other Java IDE.
• Language Basics
• Numbers and Strings

Objectives

• Get used with an integrated development environment (IDE): Netbeans.
• Get used with the Java language syntax.
• Create and run a simple application.
• Understand the following concepts: compiler, interpreter, byte-code, Java Virtual Machine (JVM), portability.
• Use the Unicode alphabet and Java special characters.
• Work with primitive data types and strings (String, StringBuilder).
• Work with one- and multi-dimensional arrays.
• Parse command line arguments.
• Perform conversions between strings and numbers.
• Split a string into tokens.
• Generate random numbers.
• Create multiple methods in the main class of the application.