Current project

src/containers/Backpack.java

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+package containers;
+
+import data.Shape;
+import exception.BackpackOverflow;
+
+import java.util.ArrayList;
+
+public class Backpack<T extends Shape> {
+    private ArrayList<T> elements;
+    private final int n;
+
+    public Backpack(int n) {
+        this.n = n;
+        try {
+            elements = new ArrayList<>();
+        } catch (NegativeArraySizeException e) {
+            System.out.println("NegativeArraySize");
+        }
+    }
+
+    public int add(T element) {
+        if (elements.size() == n) {
+            throw new BackpackOverflow();
+        } else {
+            elements.add(element);
+            sort();
+            return elements.indexOf(element);
+        }
+    }
+
+    public void remove(int i) {
+        if (elements.size() != 0) {
+            elements.remove(i);
+        }
+    }
+
+    public int size() {
+        return elements.size();
+    }
+
+    public void sort() {
+        elements.sort((a, b)-> (int)(b.getVolume() - a.getVolume()));
+    }
+}

src/controller/Controller.java

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+package controller;
+
+import containers.Backpack;
+import data.Shape;
+import gui.GUI;
+
+public class Controller {
+    private final int BACKPACK_CAPACITY = 100;
+    private final Backpack<Shape> backpack = new Backpack<>(BACKPACK_CAPACITY);
+
+    public Controller() {
+        GUI app = new GUI(this);
+        app.setVisible(true);
+    }
+
+    public String backpackStat() {
+        return "Backpack Size: " + backpack.size() + ", Backpack Capacity: " + BACKPACK_CAPACITY;
+    }
+
+    public int addElementToBackpack(Shape new_element) {
+        return backpack.add(new_element);
+    }
+
+    public void remove(int i) {
+        backpack.remove(i);
+    }
+}

src/data/Ball.java

@@ -0,0 +1,19 @@
+package data;
+
+public class Ball extends Shape {
+    double radius;
+
+    public Ball(double radius) {
+        this.radius = radius;
+    }
+
+    @Override
+    public double getVolume() {
+        return 4.0 / 3 * Math.PI * Math.pow(radius, 3);
+    }
+
+    @Override
+    public String toString() {
+        return "Ball with radius " + radius + " and Volume " + RoundAvoid(getVolume(), 4);
+    }
+}

src/data/Cube.java

@@ -0,0 +1,19 @@
+package data;
+
+public class Cube extends Shape {
+    double edge;
+
+    public Cube(double edge) {
+        this.edge = edge;
+    }
+
+    @Override
+    public double getVolume() {
+        return Math.pow(edge, 3);
+    }
+
+    @Override
+    public String toString() {
+        return "Cube with edge " + edge + " and Volume " + RoundAvoid(getVolume(), 4);
+    }
+}

src/data/Shape.java

@@ -0,0 +1,11 @@
+package data;
+
+public abstract class Shape {
+    public abstract double getVolume();
+
+    protected double RoundAvoid(double value, int places) {
+        double scale = Math.pow(10, places);
+        return Math.round(value * scale) / scale;
+    }
+}
+

src/data/Tetrahedron.java

@@ -0,0 +1,19 @@
+package data;
+
+public class Tetrahedron extends Shape {
+    double edge;
+
+    public Tetrahedron(double edge) {
+        this.edge = edge;
+    }
+
+    @Override
+    public double getVolume() {
+        return Math.pow(edge, 3) / (6 * Math.sqrt(2));
+    }
+
+    @Override
+    public String toString() {
+        return "Tetrahedron with edge " + edge + " and Volume " + RoundAvoid(getVolume(), 4);
+    }
+}

src/exception/BackpackOverflow.java

@@ -0,0 +1,7 @@
+package exception;
+
+public class BackpackOverflow extends RuntimeException {
+    public BackpackOverflow() {
+        super("Can`t add anymore to backpack");
+    }
+}

src/gui/GUI.java

@@ -0,0 +1,127 @@
+package gui;
+
+import controller.Controller;
+import data.Ball;
+import data.Cube;
+import data.Shape;
+import data.Tetrahedron;
+
+import javax.swing.*;
+import java.awt.*;
+import java.util.regex.Pattern;
+
+public class GUI extends JFrame {
+    private final DefaultListModel<Shape> listModel = new DefaultListModel<>();
+    private final JList<Shape> list = new JList<>(listModel);
+
+    private final JButton addCube = new JButton();
+    private final JButton addBall = new JButton();
+    private final JButton addTetrahedron = new JButton();
+    private final JButton deleteComponent = new JButton();
+
+    private final JLabel backpackStat = new JLabel();
+
+    private final Controller controller;
+    private final String[] statuses = new String[]{"edge of cube", "ball radius", "edge of tetrahedron"};
+
+    public GUI(Controller controller) {
+        this.controller = controller;
+        JScrollPane scrollPane = new JScrollPane();
+        scrollPane.add(list);
+
+        setMinimumSize(new Dimension(800, 800));
+        setTitle("Backpack v0.1");
+        setLocationRelativeTo(null);
+        setDefaultCloseOperation(EXIT_ON_CLOSE);
+
+        createLayout(getContentPane());
+        setElementsInfo();
+    }
+
+    private void createLayout(Container pane) {
+        BorderLayout layout = new BorderLayout();
+        pane.setLayout(layout);
+        pane.add(list, BorderLayout.CENTER);
+        pane.add(backpackStat, BorderLayout.SOUTH);
+        JPanel panel = new JPanel();
+        panel.setLayout(new GridLayout(0, 1));
+        panel.add(addCube);
+        panel.add(addBall);
+        panel.add(addTetrahedron);
+        panel.add(deleteComponent);
+        pane.add(panel, BorderLayout.EAST);
+    }
+
+    private final Pattern NUM_EX = Pattern.compile("-?\\d+(\\.\\d+)?");
+
+    private boolean isNumeric(String strNum) {
+        return NUM_EX.matcher(strNum).matches();
+    }
+
+    private void setElementsInfo() {
+        addCube.setText("Add cube");
+        addCube.addActionListener(actionEvent -> displayInputDialog(0));
+        addBall.setText("Add ball");
+        addBall.addActionListener(actionEvent -> displayInputDialog(1));
+        addTetrahedron.setText("Add tetrahedron");
+        addTetrahedron.addActionListener(actionEvent -> displayInputDialog(2));
+
+        deleteComponent.setText("Remove selected shape from Backpack");
+        deleteComponent.addActionListener(actionEvent -> {
+            if (!list.isSelectionEmpty()) {
+                int index = list.getSelectedIndex();
+                listModel.remove(index);
+                controller.remove(index);
+                backpackStat.setText(controller.backpackStat());
+            } else {
+                JOptionPane.showMessageDialog(GUI.this,
+                        "Select shape to delete first",
+                        "Error",
+                        JOptionPane.ERROR_MESSAGE);
+            }
+        });
+
+        list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
+        list.setLayoutOrientation(JList.HORIZONTAL_WRAP);
+        list.setVisibleRowCount(-1);
+
+        backpackStat.setText(controller.backpackStat());
+    }
+
+    private void displayInputDialog(int type) {
+        String message = JOptionPane.showInputDialog(
+                GUI.this,
+                "<html><h1>Enter " + statuses[type] + " (non-negative number)");
+        if (message != null && isNumeric(message) && Integer.parseInt(message) >= 0) {
+            switch (type) {
+                case 0: {
+                    addToBackpack(new Cube(Integer.parseInt(message)));
+                    break;
+                }
+                case 1: {
+                    addToBackpack(new Ball(Integer.parseInt(message)));
+                    break;
+                }
+                case 2: {
+                    addToBackpack(new Tetrahedron(Integer.parseInt(message)));
+                    break;
+                }
+            }
+        } else {
+            inputError();
+        }
+    }
+
+    private void addToBackpack(Shape shape) {
+        int index = controller.addElementToBackpack(shape);
+        listModel.add(index, shape);
+        backpackStat.setText(controller.backpackStat());
+    }
+
+    private void inputError() {
+        JOptionPane.showMessageDialog(GUI.this,
+                "Seems, you enter something that is not a non-negative number :)",
+                "Error",
+                JOptionPane.ERROR_MESSAGE);
+    }
+}

src/main/Main.java

@@ -0,0 +1,9 @@
+package main;
+
+import controller.Controller;
+
+public class Main {
+    public static void main(String[] args) {
+        Controller controller = new Controller();
+    }
+}