ComplexNumber.java

public class ComplexNumber {
    private float real, imaginary;
    
    public ComplexNumber () {
        this (0f, 0f);
    }
    
    public ComplexNumber (float real, float imaginary) {
        this.real = real;
        this.imaginary = imaginary;
    }
    
    public float getReal () {
        return (real);
    }
    
    public void setReal (float real) {
        this.real = real;
    }
    
    public float getImaginary () {
        return (imaginary);
    }
    
    public void setImaginary (float imaginary) {
        this.imaginary = imaginary;
    }
    
    public ComplexNumber multiply (ComplexNumber factor) {
        ComplexNumber product = new ComplexNumber ();
        
        product.setReal ((real * factor.real) - (imaginary * factor.imaginary));
        product.setImaginary ((imaginary * factor.real) + (real * factor.imaginary));
        
        return (product);
    }
    
    public ComplexNumber divide (ComplexNumber divisor) {
        ComplexNumber quotient = new ComplexNumber ();
        
        quotient.setReal (((real * divisor.real) + (imaginary * divisor.imaginary)) /
            (float) (Math.pow (divisor.real, 2) + Math.pow (divisor.imaginary, 2)));
        quotient.setImaginary (((imaginary * divisor.real) - (real * divisor.imaginary)) /
            (float) (Math.pow (divisor.real, 2) + Math.pow (divisor.imaginary, 2)));
        
        return (quotient);
    }
    
    public String toString () {
        String string;
        
        string = String.format ("%.2f + %.2fi", real, imaginary);
        
        return (string);
    }
    
    public void print () {
        System.out.println (toString ());
    }
}

ComplexNumberTest.java

public class ComplexNumberTest extends junit.framework.TestCase {
    ComplexNumber nullNumber1, nullNumber2;
    ComplexNumber factor1, factor2, product;
    ComplexNumber dividend, divisor, quotient;
    
    public ComplexNumberTest () {
    }
    
    protected void setUp () {
        System.out.println (String.format ("%s test started!", getName ()));
        
        nullNumber1 = new ComplexNumber ();
        
        factor1 = new ComplexNumber (13f, -3f);
        factor2 = new ComplexNumber (6f, 2f);
        
        dividend = new ComplexNumber (3f, 4f);
        divisor = new ComplexNumber (2f, -5f);
    }
    
    protected void tearDown () {
        System.out.println (String.format ("%s test finished!", getName ()));
    }
    
    public void testConstructor () {
        nullNumber2 = new ComplexNumber ();
        
        assertEquals ("Constructor without arguments fails (inequality)!", nullNumber1.toString (),
            nullNumber2.toString ());
        assertNotNull ("Constructor without argument fails (null)!", nullNumber2);
    }
    
    public void testMultiplying () {
        product = new ComplexNumber ();
        product = factor1.multiply (factor2);
        
        assertEquals ("Multiplying fails (real)!", product.getReal (), 84f);
        assertEquals ("Multiplying fails (imaginary)!", product.getImaginary (), 8f);
        assertEquals ("Multiplying fails (string)!", product.toString (), "84.00 + 8.00i");
    }
    
    public void testDividing () {
        quotient = new ComplexNumber ();
        quotient = dividend.divide (divisor);
        
        assertEquals ("Dividing fails (real)!", quotient.getReal (), -0.48, 0.01);
        assertEquals ("Dividing fails (imaginary)!", quotient.getImaginary (), 0.79, 0.01);
        assertEquals ("Dividing fails (string)!", quotient.toString (), "-0.48 + 0.79i");
    }
}

Person.java

import java.util.Scanner;

public class Person {
    private Scanner scanner = new Scanner (System.in);
    protected Song[] songs;
    protected String name;
    protected int year;
    
    public Person () {
        this ("No name", 1990);
    }
    
    public Person (String name, int year) {
        this.name = name;
        this.year = year;
        songs = setSongs ();
    }
    
    public Person (Person person) {
        name = person.getName ();
        year = person.getYear ();
        songs = person.getSongs ();
    }
    
    public Song[] getSongs () {
        return (songs);
    }
    
    protected Song[] setSongs () {
        Song[] songs = new Song[readNumber ()];
        
        for (int i = 0; i < songs.length; i++) {
            songs[i] = new Song (readString (i));
        }
        
        return (songs);
    }
            
    public String getName () {
        return (name);
    }
    
    public void setName (String name) {
        this.name = name;
    }
    
    public int getYear () {
        return (year);
    }
    
    public void setYear (int year) {
        this.year = year;
    }
    
    private int readNumber () {
        int i;
        
        System.out.printf ("%-15s: ", "Number of songs");
        i = scanner.nextInt ();
        
        return (i);
    }
    
    private String readString (int i) {
        String string;
        
        string = String.format ("%d. song", (i + 1));
        System.out.printf ("%-15s: ", string);
        
        return (scanner.next ());
    }
    
    public String songsToString () {
        String string = "";
        
        for (int i = 0; i < songs.length; i++) {
            string += songs[i].toString ();
            
            if ((i + 1) != songs.length) {
                string += ", ";
            } else {
                string += ".";
            }
        }
        
        return (string);
    }
    
    public String toString () {
        return (String.format ("%-15s: %s\n%-15s: %d\n%-15s: %s", "Name", getName (),
            "Year of birth", getYear (), "Favourite songs", songsToString ()));
    }
    
    public void print () {
        System.out.println (this);
    }
}

Point.java

public class Point {
    private int x, y;
    
    public Point () {
        this (0, 0);
    }
    
    public Point (int x, int y) {
        this.x = x;
        this.y = y;
    }
    
    public Point (Point point) {
        x = point.getX ();
        y = point.getY ();
    }
    
    public int getX () {
        return (x);
    }
    
    public void setX (int x) {
        this.x = x;
    }
    
    public int getY () {
        return (y);
    }
    
    public void setY (int y) {
        this.y = y;
    }
    
    public void move (int dx, int dy) {
        setX (getX () + dx);
        setY (getY () + dy);
    }
    
    public String toString () {
        return (String.format ("[%d; %d]", getX (), getY ()));
    }
}

Song.java

public class Song {
    private String name;
    
    public Song (String name) {
        this.name = name;
    }
    
    public String toString () {
        return (name);
    }
}

Student.java

public class Student extends Person {
    private String field;
    private int credits;
    
    public Student () {
        this ("No name", 1990, "None", 0);
    }
    
    public Student (String name, int year, String field, int credits) {
        this.name = name;
        this.year = year;
        //songs = setSongs ();
        this.field = field;
        this.credits = credits;
    }
    
    public Student (Student student) {
        name = student.getName ();
        year = student.getYear ();
        songs = student.getSongs ();
        field = student.getField ();
        credits = student.getCredits ();
    }
    
    public String getField () {
        return (field);
    }
    
    public void setField (String field) {
        this.field = field;
    }
    
    public int getCredits () {
        return (credits);
    }
    
    public void setCredits () {
        this.credits = credits;
    }
    
    public String toString () {
        return (String.format ("%-15s: %s\n%-15s: %d\n%-15s: %s\n%-15s: %s\n%-15s: %d",
            "Name", getName (), "Year of birth", getYear (), "Favourite songs", songsToString (),
            "Field", getField (), "Credits", getCredits ()));
    }
    
    public void print () {
        System.out.println (this);
    }
}

StudentTest.java

public class StudentTest {
    public static void main (String args[]) {
        Student student1, student2;
        
        student1 = new Student ();
        student2 = new Student ("Sue", 1980, "Informatics", 60);
        
        student1.print ();
        student2.print ();
    }
}

Triangle.java

public class Triangle {
    private Point a, b, c;
    
    public Triangle () {
        this (new Point (), new Point (), new Point ());
    }
    
    public Triangle (Point a, Point b, Point c) {
        this.a = new Point (a);
        this.b = new Point (b);
        this.c = new Point (c);
    }

    public Triangle (Triangle triangle) {
        a = new Point (triangle.getA ());
        b = new Point (triangle.getB ());
        c = new Point (triangle.getC ());
    }
    
    public Point getA () {
        return (a);
    }
    
    public Point getB () {
        return (b);
    }
    
    public Point getC () {
        return (c);
    }
    
    public void move (int dx, int dy) {
        a.move (dx, dy);
        b.move (dx, dy);
        c.move (dx, dy);
    }
    
    public String toString () {
        return (String.format ("A: %s, B: %s, C: %s", a, b, c));
    }
    
    public void print () {
        System.out.println (this);
    }
}

TriangleTest.java

public class TriangleTest {
    public static void main (String args[]) {
        Triangle triangle1, triangle2;
        
        triangle1 = new Triangle ();
        triangle2 = new Triangle (new Point (20, 20), new Point (30, 30), new Point (10, 30));
        
        triangle1.print ();
        triangle1.move (10, 10);
        triangle1.print ();
        
        triangle2.print ();
        triangle2.move (-10, -10);
        triangle2.print ();
    }
}