11b - exam solution, stream api intro

materials/2023-2024/11b/2023-12-22-exam-2-solution/exam-2-solution/exam-2-solution.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

materials/2023-2024/11b/2023-12-22-exam-2-solution/exam-2-solution/src/Figure.java

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+public abstract class Figure {
+    protected Game game;
+    protected String owner;
+    protected Game.Pos pos;
+
+//    private char[] display;
+    private char display;
+
+    public Figure(Game game, String owner, Game.Pos pos, char[] display) {
+        this.game = game;
+        this.owner = owner;
+        this.pos = pos;
+//        this.display = display;
+        this.display = owner == "white" ? display[0] : display[1];
+    }
+
+    public void move(String pos) {
+        Game.Pos newPos = Game.stringToPos(pos);
+//        1. validate pos is in board
+        if(newPos.row < 0 || newPos.col < 0)
+            throw new IllegalArgumentException("Invalid position");
+        if(newPos.row > 7 || newPos.col > 7)
+            throw new IllegalArgumentException("Invalid position");
+//        2. validate with canMove
+        if(!canMove(pos))
+            throw new IllegalArgumentException("Invalid position");
+//        3. validate field is empty or owner by oponent
+        Figure targetCell = game.getAt(pos);
+        if(targetCell != null && targetCell.owner == owner)
+            throw new IllegalArgumentException("Cannot take own piece");
+//        4. board[pos] = this
+        game.setAt(newPos.toString(), this);
+//        5. board[this.pos] = null
+        game.setAt(this.pos.toString(), null);
+//        6. this.pos = pos
+        this.pos = newPos;
+    }
+
+    protected abstract boolean canMove(String pos);
+
+    @Override
+    public String toString() {
+        return "" + display;
+//        if(owner == "white")
+//            return "" + display[0];
+//        else
+//            return "" + display[1];
+    }
+}

materials/2023-2024/11b/2023-12-22-exam-2-solution/exam-2-solution/src/Game.java

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+public class Game {
+    private Figure[][] board;
+
+    private King whiteKing = null;
+    private King blackKing = null;
+
+    public Game() {
+        board = new Figure[8][8];
+
+        board[0][0] = new Rook(this, "white", new Pos(0, 0));
+        board[3][0] = whiteKing = new King(this, "white", new Pos(0, 3));
+
+        board[0][7] = new Rook(this, "black", new Pos(7, 0));
+        board[3][7] = blackKing = new King(this, "black", new Pos(7, 3));
+    }
+
+    public Figure getAt(String pos) {
+        Pos newPos = stringToPos(pos);
+        return board[newPos.row][newPos.col];
+    }
+
+    public void setAt(String pos, Figure fig) {
+        Pos newPos = stringToPos(pos);
+        board[newPos.row][newPos.col] = fig;
+    }
+
+    public void moveFigure(String start, String end) {
+        Figure fig = getAt(start);
+        fig.move(end);
+    }
+
+    public void printBoard() {
+        for(int row = 0; row < 8; row++) {
+            for(int col = 0; col < 8; col++) {
+                Figure fig = getAt(new Pos(row, col).toString());
+                if(fig == null) System.out.print('-');
+                else System.out.print(fig);
+            }
+            System.out.println("");
+        }
+    }
+
+    public void checkForWinner() {
+        if(whiteKing.isMate()) {
+            System.out.println("Black wins");
+        } else if(blackKing.isMate()) {
+            System.out.println("White wins");
+        }
+    }
+
+    public static class Pos {
+        public int row;
+        public int col;
+
+        public Pos(int row, int col) {
+            this.row = row;
+            this.col = col;
+        }
+
+        @Override
+        public String toString() {
+            int r = 'A' + row;
+            int c = '1' + col;
+            return Character.toString(r) + Character.toString(c);
+        }
+    }
+
+    public static Pos stringToPos(String pos) {
+        int col = pos.charAt(0) - 'A';
+        int row = pos.charAt(1) - '1';
+
+        return new Pos(row, col);
+    }
+}

materials/2023-2024/11b/2023-12-22-exam-2-solution/exam-2-solution/src/King.java

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+public class King extends Figure {
+    public King(Game game, String owner, Game.Pos pos) {
+        super(game, owner, pos, new char[] {'K', 'k'});
+    }
+
+    @Override
+    protected boolean canMove(String pos) {
+        return false;
+    }
+
+    public boolean isCheck() {
+        return false;
+    }
+
+    public boolean isMate() {
+        return false;
+    }
+}

materials/2023-2024/11b/2023-12-22-exam-2-solution/exam-2-solution/src/Main.java

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+public class Main {
+    public static void main(String[] args) {
+//        String[][] arr = new String[10][5];
+////        for(int i = 0; i < 5; i++) {
+////            for(int j = 0; j < 10; j++) {
+////                arr[i][j] = i + "-" + j;
+////            }
+////        }
+//        for(int x = 0; x < 10; x++) {
+//            for(int y = 0; y < 5; y++) {
+//                arr[x][y] = x + "-" + y;
+//            }
+//        }
+//
+//        for(int row = 0; row < 5; row++) {
+//            for(int column = 0; column < 10; column++) {
+//                System.out.print(arr[row][column] + " ");
+//            }
+//            System.out.println("");
+//        }
+
+        Game g = new Game();
+        g.printBoard();
+
+        g.moveFigure("A1", "A4");
+        g.printBoard();
+    }
+}

materials/2023-2024/11b/2023-12-22-exam-2-solution/exam-2-solution/src/Rook.java

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+public class Rook extends Figure {
+    public Rook(Game game, String owner, Game.Pos pos) {
+        super(game, owner, pos, new char[] {'R', 'r'});
+    }
+
+    @Override
+    protected boolean canMove(String pos) {
+        return true;
+    }
+}

materials/2023-2024/11b/2024-04-08-stream-api/stream-api/src/Main.java

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+import java.util.*;
+import java.util.function.BiConsumer;
+import java.util.function.BinaryOperator;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import java.util.stream.BaseStream;
+import java.util.stream.Collector;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class Main {
+    public static class User {
+        public String firstName;
+        public String lastName;
+        public int age;
+
+        public User(String firstName, String lastName, int age) {
+            this.firstName = firstName;
+            this.lastName = lastName;
+            this.age = age;
+        }
+
+        @Override
+        public String toString() {
+            return "User{" +
+                    "firstName='" + firstName + '\'' +
+                    ", lastName='" + lastName + '\'' +
+                    ", age=" + age +
+                    '}';
+        }
+    }
+
+    public static void main(String[] args) {
+        int[] arr = {5, 3, 1, 2, 4};
+
+        BaseStream foo = Arrays.stream(arr);
+        Object[] res = Arrays.stream(arr)
+                .filter(a -> a > 3)
+                .sorted()
+                .map(a -> a * 2)
+                .mapToObj(a -> "foo-" + a)
+                .toArray();
+
+        System.out.println(Arrays.toString(res));
+
+        Random rand = new Random();
+        List<User> users = Stream.generate(() ->
+                new User("Name" + rand.nextInt(), "Name" + rand.nextInt(), rand.nextInt())
+            )
+            .limit(10)
+            .toList();
+
+        System.out.println(users);
+
+        List<User> res2 = users.stream()
+//            .sorted((a, b) -> a.firstName.compareTo(b.firstName))
+            .sorted(Comparator.comparing(a -> a.firstName))
+            .skip(10)
+            .limit(5)
+            .toList();
+
+        System.out.println(res2);
+
+        Optional<User> bar = users.stream()
+                .findFirst();
+//        bar.ifPresent(System.out::println);
+        if(!bar.isEmpty())
+            System.out.println(bar.get());
+
+//        users.stream()
+//                .collect(Collectors.toList())
+//                .collect(new Collector<User, Object, Object>() {
+//                    @Override
+//                    public Supplier<Object> supplier() {
+//                        return null;
+//                    }
+//
+//                    @Override
+//                    public BiConsumer<Object, User> accumulator() {
+//                        return null;
+//                    }
+//
+//                    @Override
+//                    public BinaryOperator<Object> combiner() {
+//                        return null;
+//                    }
+//
+//                    @Override
+//                    public Function<Object, Object> finisher() {
+//                        return null;
+//                    }
+//
+//                    @Override
+//                    public Set<Characteristics> characteristics() {
+//                        return null;
+//                    }
+//                })
+    }
+}

materials/2023-2024/11b/2024-04-08-stream-api/stream-api/stream-api.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>