Merge branch 'master' into BAEL-4158

2020-06-14 09:57:03 +03:00
parent 0828e8c3cd cdbdf611d2
commit 3dff206800
381 changed files with 6905 additions and 596 deletions
@@ -0,0 +1,208 @@
+package com.baeldung.algorithms.play2048;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.LinkedList;
+import java.util.List;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class Board {
+    private static final Logger LOG = LoggerFactory.getLogger(Board.class);
+
+    private final int[][] board;
+
+    private final int score;
+
+    public Board(int size) {
+        assert(size > 0);
+
+        this.board = new int[size][];
+        this.score = 0;
+
+        for (int x = 0; x < size; ++x) {
+            this.board[x] = new int[size];
+            for (int y = 0; y < size; ++y) {
+                board[x][y] = 0;
+            }
+        }
+    }
+
+    private Board(int[][] board, int score) {
+        this.score = score;
+        this.board = new int[board.length][];
+
+        for (int x = 0; x < board.length; ++x) {
+            this.board[x] = Arrays.copyOf(board[x], board[x].length);
+        }
+    }
+
+    public int getSize() {
+        return board.length;
+    }
+
+    public int getScore() {
+        return score;
+    }
+
+    public int getCell(Cell cell) {
+        int x = cell.getX();
+        int y = cell.getY();
+        assert(x >= 0 && x < board.length);
+        assert(y >= 0 && y < board.length);
+
+        return board[x][y];
+    }
+
+    public boolean isEmpty(Cell cell) {
+        return getCell(cell) == 0;
+    }
+
+    public List<Cell> emptyCells() {
+        List<Cell> result = new ArrayList<>();
+        for (int x = 0; x < board.length; ++x) {
+            for (int y = 0; y < board[x].length; ++y) {
+                Cell cell = new Cell(x, y);
+                if (isEmpty(cell)) {
+                    result.add(cell);
+                }
+            }
+        }
+        return result;
+    }
+
+    public Board placeTile(Cell cell, int number) {
+        if (!isEmpty(cell)) {
+            throw new IllegalArgumentException("That cell is not empty");
+        }
+
+        Board result = new Board(this.board, this.score);
+        result.board[cell.getX()][cell.getY()] = number;
+        return result;
+    }
+
+    public Board move(Move move) {
+        // Clone the board
+        int[][] tiles = new int[this.board.length][];
+        for (int x = 0; x < this.board.length; ++x) {
+            tiles[x] = Arrays.copyOf(this.board[x], this.board[x].length);
+        }
+
+        LOG.debug("Before move: {}", Arrays.deepToString(tiles));
+        // If we're doing an Left/Right move then transpose the board to make it a Up/Down move
+        if (move == Move.LEFT || move == Move.RIGHT) {
+            tiles = transpose(tiles);
+            LOG.debug("After transpose: {}", Arrays.deepToString(tiles));
+        }
+        // If we're doing a Right/Down move then reverse the board.
+        // With the above we're now always doing an Up move
+        if (move == Move.DOWN || move == Move.RIGHT) {
+            tiles = reverse(tiles);
+            LOG.debug("After reverse: {}", Arrays.deepToString(tiles));
+        }
+        LOG.debug("Ready to move: {}", Arrays.deepToString(tiles));
+
+        // Shift everything up
+        int[][] result = new int[tiles.length][];
+        int newScore = 0;
+        for (int x = 0; x < tiles.length; ++x) {
+            LinkedList<Integer> thisRow = new LinkedList<>();
+            for (int y = 0; y < tiles[0].length; ++y) {
+                if (tiles[x][y] > 0) {
+                    thisRow.add(tiles[x][y]);
+                }
+            }
+
+            LOG.debug("Unmerged row: {}", thisRow);
+            LinkedList<Integer> newRow = new LinkedList<>();
+            while (thisRow.size() >= 2) {
+                int first = thisRow.pop();
+                int second = thisRow.peek();
+                LOG.debug("Looking at numbers {} and {}", first, second);
+                if (second == first) {
+                    LOG.debug("Numbers match, combining");
+                    int newNumber = first * 2;
+                    newRow.add(newNumber);
+                    newScore += newNumber;
+                    thisRow.pop();
+                } else {
+                    LOG.debug("Numbers don't match");
+                    newRow.add(first);
+                }
+            }
+            newRow.addAll(thisRow);
+            LOG.debug("Merged row: {}", newRow);
+
+            result[x] = new int[tiles[0].length];
+            for (int y = 0; y < tiles[0].length; ++y) {
+                if (newRow.isEmpty()) {
+                    result[x][y] = 0;
+                } else {
+                    result[x][y] = newRow.pop();
+                }
+            }
+        }
+        LOG.debug("After moves: {}", Arrays.deepToString(result));
+
+        // Un-reverse the board
+        if (move == Move.DOWN || move == Move.RIGHT) {
+            result = reverse(result);
+            LOG.debug("After reverse: {}", Arrays.deepToString(result));
+        }
+        // Un-transpose the board
+        if (move == Move.LEFT || move == Move.RIGHT) {
+            result = transpose(result);
+            LOG.debug("After transpose: {}", Arrays.deepToString(result));
+        }
+        return new Board(result, this.score + newScore);
+    }
+
+    private static int[][] transpose(int[][] input) {
+        int[][] result = new int[input.length][];
+
+        for (int x = 0; x < input.length; ++x) {
+            result[x] = new int[input[0].length];
+            for (int y = 0; y < input[0].length; ++y) {
+                result[x][y] = input[y][x];
+            }
+        }
+
+        return result;
+    }
+
+    private static int[][] reverse(int[][] input) {
+        int[][] result = new int[input.length][];
+
+        for (int x = 0; x < input.length; ++x) {
+            result[x] = new int[input[0].length];
+            for (int y = 0; y < input[0].length; ++y) {
+                result[x][y] = input[x][input.length - y - 1];
+            }
+        }
+
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return Arrays.deepToString(board);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        Board board1 = (Board) o;
+        return Arrays.deepEquals(board, board1.board);
+    }
+
+    @Override
+    public int hashCode() {
+        return Arrays.deepHashCode(board);
+    }
+}
@@ -0,0 +1,26 @@
+package com.baeldung.algorithms.play2048;
+
+import java.util.StringJoiner;
+
+public class Cell {
+    private int x;
+    private int y;
+
+    public Cell(int x, int y) {
+        this.x = x;
+        this.y = y;
+    }
+
+    public int getX() {
+        return x;
+    }
+
+    public int getY() {
+        return y;
+    }
+
+    @Override
+    public String toString() {
+        return new StringJoiner(", ", Cell.class.getSimpleName() + "[", "]").add("x=" + x).add("y=" + y).toString();
+    }
+}
@@ -0,0 +1,27 @@
+package com.baeldung.algorithms.play2048;
+
+import java.security.SecureRandom;
+import java.util.List;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class Computer {
+    private static final Logger LOG = LoggerFactory.getLogger(Computer.class);
+
+    private final SecureRandom rng = new SecureRandom();
+
+    public Board makeMove(Board input) {
+        List<Cell> emptyCells = input.emptyCells();
+        LOG.info("Number of empty cells: {}", emptyCells.size());
+
+        double numberToPlace = rng.nextDouble();
+        LOG.info("New number probability: {}", numberToPlace);
+
+        int indexToPlace = rng.nextInt(emptyCells.size());
+        Cell cellToPlace = emptyCells.get(indexToPlace);
+        LOG.info("Placing number into empty cell: {}", cellToPlace);
+
+        return input.placeTile(cellToPlace, numberToPlace >= 0.9 ? 4 : 2);
+    }
+}
@@ -0,0 +1,126 @@
+package com.baeldung.algorithms.play2048;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.apache.commons.math3.util.Pair;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class Human {
+    private static final Logger LOG = LoggerFactory.getLogger(Human.class);
+
+    public Board makeMove(Board input) {
+        // For each move in MOVE
+        //   Generate board from move
+        //   Generate Score for Board
+        // Return board with the best score
+        //
+        // Generate Score
+        //   If Depth Limit
+        //     Return Final Score
+        //   Total Score = 0
+        //   For every empty square in new board
+        //     Generate board with "2" in square
+        //       Calculate Score
+        //       Total Score += (Score * 0.9)
+        //     Generate board with "4" in square
+        //       Calculate Score
+        //       Total Score += (Score * 0.1)
+        //
+        // Calculate Score
+        //   For each move in MOVE
+        //     Generate board from move
+        //     Generate score for board
+        //   Return the best generated score
+
+        return Arrays.stream(Move.values())
+            .parallel()
+            .map(input::move)
+            .filter(board -> !board.equals(input))
+            .max(Comparator.comparingInt(board -> generateScore(board, 0)))
+            .orElse(input);
+    }
+
+    private int generateScore(Board board, int depth) {
+        if (depth >= 3) {
+            int finalScore = calculateFinalScore(board);
+            LOG.debug("Final score for board {}: {}", board,finalScore);
+            return finalScore;
+        }
+
+        return board.emptyCells().stream()
+            .parallel()
+            .flatMap(cell -> Stream.of(new Pair<>(cell, 2), new Pair<>(cell, 4)))
+            .mapToInt(move -> {
+                LOG.debug("Simulating move {} at depth {}", move, depth);
+                Board newBoard = board.placeTile(move.getFirst(), move.getSecond());
+                int boardScore = calculateScore(newBoard, depth + 1);
+                int calculatedScore = (int) (boardScore * (move.getSecond() == 2 ? 0.9 : 0.1));
+                LOG.debug("Calculated score for board {} and move {} at depth {}: {}", newBoard, move, depth, calculatedScore);
+                return calculatedScore;
+            })
+            .sum();
+    }
+
+    private int calculateScore(Board board, int depth) {
+        return Arrays.stream(Move.values())
+            .parallel()
+            .map(board::move)
+            .filter(moved -> !moved.equals(board))
+            .mapToInt(newBoard -> generateScore(newBoard, depth))
+            .max()
+            .orElse(0);
+    }
+
+    private int calculateFinalScore(Board board) {
+        List<List<Integer>> rowsToScore = new ArrayList<>();
+        for (int i = 0; i < board.getSize(); ++i) {
+            List<Integer> row = new ArrayList<>();
+            List<Integer> col = new ArrayList<>();
+
+            for (int j = 0; j < board.getSize(); ++j) {
+                row.add(board.getCell(new Cell(i, j)));
+                col.add(board.getCell(new Cell(j, i)));
+            }
+
+            rowsToScore.add(row);
+            rowsToScore.add(col);
+        }
+
+        return rowsToScore.stream()
+            .parallel()
+            .mapToInt(row -> {
+                List<Integer> preMerged = row.stream()
+                    .filter(value -> value != 0)
+                    .collect(Collectors.toList());
+
+                int numMerges = 0;
+                int monotonicityLeft = 0;
+                int monotonicityRight = 0;
+                for (int i = 0; i < preMerged.size() - 1; ++i) {
+                    Integer first = preMerged.get(i);
+                    Integer second = preMerged.get(i + 1);
+                    if (first.equals(second)) {
+                        ++numMerges;
+                    } else if (first > second) {
+                        monotonicityLeft += first - second;
+                    } else {
+                        monotonicityRight += second - first;
+                    }
+                }
+
+                int score = 1000;
+                score += 250 * row.stream().filter(value -> value == 0).count();
+                score += 750 * numMerges;
+                score -= 10 * row.stream().mapToInt(value -> value).sum();
+                score -= 50 * Math.min(monotonicityLeft, monotonicityRight);
+                return score;
+            })
+            .sum();
+    }
+}
@@ -0,0 +1,8 @@
+package com.baeldung.algorithms.play2048;
+
+public enum Move {
+    UP,
+    DOWN,
+    LEFT,
+    RIGHT
+}
@@ -0,0 +1,73 @@
+package com.baeldung.algorithms.play2048;
+
+public class Play2048 {
+    private static final int SIZE = 3;
+    private static final int INITIAL_NUMBERS = 2;
+
+    public static void main(String[] args) {
+        // The board and players
+        Board board = new Board(SIZE);
+        Computer computer = new Computer();
+        Human human = new Human();
+
+        // The computer has two moves first
+        System.out.println("Setup");
+        System.out.println("=====");
+        for (int i = 0; i < INITIAL_NUMBERS; ++i) {
+            board = computer.makeMove(board);
+        }
+
+        printBoard(board);
+        do {
+            board = human.makeMove(board);
+            System.out.println("Human move");
+            System.out.println("==========");
+            printBoard(board);
+
+            board = computer.makeMove(board);
+            System.out.println("Computer move");
+            System.out.println("=============");
+            printBoard(board);
+        } while (!board.emptyCells().isEmpty());
+
+        System.out.println("Final Score: " + board.getScore());
+
+    }
+
+    private static void printBoard(Board board) {
+        StringBuilder topLines = new StringBuilder();
+        StringBuilder midLines = new StringBuilder();
+        for (int x = 0; x < board.getSize(); ++x) {
+            topLines.append("+--------");
+            midLines.append("|        ");
+        }
+        topLines.append("+");
+        midLines.append("|");
+
+
+        for (int y = 0; y < board.getSize(); ++y) {
+            System.out.println(topLines);
+            System.out.println(midLines);
+            for (int x = 0; x < board.getSize(); ++x) {
+                Cell cell = new Cell(x, y);
+                System.out.print("|");
+                if (board.isEmpty(cell)) {
+                    System.out.print("        ");
+                } else {
+                    StringBuilder output = new StringBuilder(Integer.toString(board.getCell(cell)));
+                    while (output.length() < 8) {
+                        output.append(" ");
+                        if (output.length() < 8) {
+                            output.insert(0, " ");
+                        }
+                    }
+                    System.out.print(output);
+                }
+            }
+            System.out.println("|");
+            System.out.println(midLines);
+        }
+        System.out.println(topLines);
+        System.out.println("Score: " + board.getScore());
+    }
+}
@@ -0,0 +1,14 @@
+package com.baeldung.determinedatatype
+
+class Person {
+    
+    private int ageAsInt
+    private Double ageAsDouble
+    private String ageAsString
+    
+    Person() {}
+    Person(int ageAsInt) { this.ageAsInt =  ageAsInt}
+    Person(Double ageAsDouble) { this.ageAsDouble =  ageAsDouble}
+    Person(String ageAsString) { this.ageAsString =  ageAsString}    
+}
+class Student extends Person {}
@@ -0,0 +1,56 @@
+package com.baeldung.determinedatatype
+
+import org.junit.Assert
+import org.junit.Test
+import com.baeldung.determinedatatype.Person
+
+public class PersonTest {
+    
+    @Test
+    public void givenWhenParameterTypeIsInteger_thenReturnTrue() {
+        Person personObj = new Person(10)
+        Assert.assertTrue(personObj.ageAsInt instanceof Integer)
+    }
+    
+    @Test
+    public void givenWhenParameterTypeIsDouble_thenReturnTrue() {
+        Person personObj = new Person(10.0)
+        Assert.assertTrue((personObj.ageAsDouble).getClass() == Double)
+    }
+    
+    @Test
+    public void givenWhenParameterTypeIsString_thenReturnTrue() {
+        Person personObj = new Person("10 years")
+        Assert.assertTrue(personObj.ageAsString.class == String)
+    }
+    
+    @Test
+    public void givenClassName_WhenParameterIsInteger_thenReturnTrue() {
+        Assert.assertTrue(Person.class.getDeclaredField('ageAsInt').type == int.class)
+    }
+    
+    @Test
+    public void givenWhenObjectIsInstanceOfType_thenReturnTrue() {
+        Person personObj = new Person()
+        Assert.assertTrue(personObj instanceof Person)
+    }
+
+    @Test
+    public void givenWhenInstanceIsOfSubtype_thenReturnTrue() {
+        Student studentObj = new Student()
+        Assert.assertTrue(studentObj in Person)
+    }
+    
+    @Test
+    public void givenGroovyList_WhenFindClassName_thenReturnTrue() {
+      def ageList = ['ageAsString','ageAsDouble', 10]   
+      Assert.assertTrue(ageList.class == ArrayList)     
+      Assert.assertTrue(ageList.getClass() == ArrayList)
+    }
+    
+    @Test
+    public void givenGrooyMap_WhenFindClassName_thenReturnTrue() {
+      def ageMap = [ageAsString: '10 years', ageAsDouble: 10.0]
+      Assert.assertFalse(ageMap.class == LinkedHashMap)
+    }
+}
@@ -4,19 +4,19 @@ import java.util.Objects;

 public record Person (String name, String address) {
 	
-	public static String UNKWOWN_ADDRESS = "Unknown";
-	public static String UNNAMED = "Unnamed";
+	  public static String UNKNOWN_ADDRESS = "Unknown";
+	  public static String UNNAMED = "Unnamed";

-	public Person {
-		Objects.requireNonNull(name);
-		Objects.requireNonNull(address);
-	}
+	  public Person {
+		    Objects.requireNonNull(name);
+		    Objects.requireNonNull(address);
+	  }
 	
-	public Person(String name) {
-		this(name, UNKWOWN_ADDRESS);
-	}
+	  public Person(String name) {
+		    this(name, UNKNOWN_ADDRESS);
+	  }
 	
-	public static Person unnamed(String address) {
-		return new Person(UNNAMED, address);
-	}
-}
+	  public static Person unnamed(String address) {
+		    return new Person(UNNAMED, address);
+	  }
+}
@@ -134,7 +134,7 @@ public class PersonTest {
        Person person = new Person(name);

        assertEquals(name, person.name());
-        assertEquals(Person.UNKWOWN_ADDRESS, person.address());
+        assertEquals(Person.UNKNOWN_ADDRESS, person.address());
    }

    @Test
@@ -147,4 +147,4 @@ public class PersonTest {
        assertEquals(Person.UNNAMED, person.name());
        assertEquals(address, person.address());
    }
-}
+}
@@ -4,7 +4,7 @@
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
-    <artifactId>core-java-8-datetime</artifactId>
+    <artifactId>core-java-8-datetime-2</artifactId>
    <version>${project.parent.version}</version>
    <name>core-java-8-datetime</name>
    <packaging>jar</packaging>
@@ -41,7 +41,6 @@
    </dependencies>

    <build>
-        <finalName>core-java-datetime-java8</finalName>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
@@ -5,7 +5,7 @@ import org.junit.Test;
 import java.lang.invoke.MethodHandles;
 import java.lang.invoke.VarHandle;

-import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertEquals;

 public class VariableHandlesUnitTest {

@@ -18,25 +18,23 @@ public class VariableHandlesUnitTest {

    @Test
    public void whenVariableHandleForPublicVariableIsCreated_ThenItIsInitializedProperly() throws NoSuchFieldException, IllegalAccessException {
-        VarHandle publicIntHandle = MethodHandles
+        VarHandle PUBLIC_TEST_VARIABLE = MethodHandles
          .lookup()
          .in(VariableHandlesUnitTest.class)
          .findVarHandle(VariableHandlesUnitTest.class, "publicTestVariable", int.class);

-        assertThat(publicIntHandle.coordinateTypes().size() == 1);
-        assertThat(publicIntHandle.coordinateTypes().get(0) == VariableHandlesUnitTest.class);
-
+        assertEquals(1, PUBLIC_TEST_VARIABLE.coordinateTypes().size());
+        assertEquals(VariableHandlesUnitTest.class, PUBLIC_TEST_VARIABLE.coordinateTypes().get(0));
    }

    @Test
    public void whenVariableHandleForPrivateVariableIsCreated_ThenItIsInitializedProperly() throws NoSuchFieldException, IllegalAccessException {
-        VarHandle privateIntHandle = MethodHandles
+        VarHandle PRIVATE_TEST_VARIABLE = MethodHandles
          .privateLookupIn(VariableHandlesUnitTest.class, MethodHandles.lookup())
          .findVarHandle(VariableHandlesUnitTest.class, "privateTestVariable", int.class);

-        assertThat(privateIntHandle.coordinateTypes().size() == 1);
-        assertThat(privateIntHandle.coordinateTypes().get(0) == VariableHandlesUnitTest.class);
-
+        assertEquals(1, PRIVATE_TEST_VARIABLE.coordinateTypes().size());
+        assertEquals(VariableHandlesUnitTest.class, PRIVATE_TEST_VARIABLE.coordinateTypes().get(0));
    }

    @Test
@@ -44,63 +42,64 @@ public class VariableHandlesUnitTest {
        VarHandle arrayVarHandle = MethodHandles
          .arrayElementVarHandle(int[].class);

-        assertThat(arrayVarHandle.coordinateTypes().size() == 2);
-        assertThat(arrayVarHandle.coordinateTypes().get(0) == int[].class);
+        assertEquals(2, arrayVarHandle.coordinateTypes().size());
+        assertEquals(int[].class, arrayVarHandle.coordinateTypes().get(0));
    }

    @Test
    public void givenVarHandle_whenGetIsInvoked_ThenValueOfVariableIsReturned() throws NoSuchFieldException, IllegalAccessException {
-        VarHandle publicIntHandle = MethodHandles
+        VarHandle PUBLIC_TEST_VARIABLE = MethodHandles
          .lookup()
          .in(VariableHandlesUnitTest.class)
          .findVarHandle(VariableHandlesUnitTest.class, "publicTestVariable", int.class);

-        assertThat((int) publicIntHandle.get(this) == 1);
+        assertEquals(1, (int) PUBLIC_TEST_VARIABLE.get(this));
    }

    @Test
    public void givenVarHandle_whenSetIsInvoked_ThenValueOfVariableIsChanged() throws NoSuchFieldException, IllegalAccessException {
-        VarHandle publicIntHandle = MethodHandles
+        VarHandle VARIABLE_TO_SET = MethodHandles
          .lookup()
          .in(VariableHandlesUnitTest.class)
          .findVarHandle(VariableHandlesUnitTest.class, "variableToSet", int.class);
-        publicIntHandle.set(this, 15);

-        assertThat((int) publicIntHandle.get(this) == 15);
+        VARIABLE_TO_SET.set(this, 15);
+        assertEquals(15, (int) VARIABLE_TO_SET.get(this));
    }

    @Test
    public void givenVarHandle_whenCompareAndSetIsInvoked_ThenValueOfVariableIsChanged() throws NoSuchFieldException, IllegalAccessException {
-        VarHandle publicIntHandle = MethodHandles
+        VarHandle VARIABLE_TO_COMPARE_AND_SET = MethodHandles
          .lookup()
          .in(VariableHandlesUnitTest.class)
          .findVarHandle(VariableHandlesUnitTest.class, "variableToCompareAndSet", int.class);
-        publicIntHandle.compareAndSet(this, 1, 100);

-        assertThat((int) publicIntHandle.get(this) == 100);
+        VARIABLE_TO_COMPARE_AND_SET.compareAndSet(this, 1, 100);
+        assertEquals(100, (int) VARIABLE_TO_COMPARE_AND_SET.get(this));
    }

    @Test
    public void givenVarHandle_whenGetAndAddIsInvoked_ThenValueOfVariableIsChanged() throws NoSuchFieldException, IllegalAccessException {
-        VarHandle publicIntHandle = MethodHandles
+        VarHandle VARIABLE_TO_GET_AND_ADD = MethodHandles
          .lookup()
          .in(VariableHandlesUnitTest.class)
          .findVarHandle(VariableHandlesUnitTest.class, "variableToGetAndAdd", int.class);
-        int before = (int) publicIntHandle.getAndAdd(this, 200);

-        assertThat(before == 0);
-        assertThat((int) publicIntHandle.get(this) == 200);
+        int before = (int) VARIABLE_TO_GET_AND_ADD.getAndAdd(this, 200);
+
+        assertEquals(0, before);
+        assertEquals(200, (int) VARIABLE_TO_GET_AND_ADD.get(this));
    }

    @Test
    public void givenVarHandle_whenGetAndBitwiseOrIsInvoked_ThenValueOfVariableIsChanged() throws NoSuchFieldException, IllegalAccessException {
-        VarHandle publicIntHandle = MethodHandles
+        VarHandle VARIABLE_TO_BITWISE_OR = MethodHandles
          .lookup()
          .in(VariableHandlesUnitTest.class)
          .findVarHandle(VariableHandlesUnitTest.class, "variableToBitwiseOr", byte.class);
-        byte before = (byte) publicIntHandle.getAndBitwiseOr(this, (byte) 127);
+        byte before = (byte) VARIABLE_TO_BITWISE_OR.getAndBitwiseOr(this, (byte) 127);

-        assertThat(before == 0);
-        assertThat(variableToBitwiseOr == 127);
+        assertEquals(0, before);
+        assertEquals(127, (byte) VARIABLE_TO_BITWISE_OR.get(this));
    }
 }
@@ -0,0 +1,42 @@
+package com.baeldung.arrays;
+
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public class JavaArraysToStringUnitTest {
+
+    @Test
+    public void givenInstanceOfArray_whenTryingToConvertToString_thenNameOfClassIsShown() {
+        Object[] arrayOfObjects = { "John", 2, true };
+        assertTrue(arrayOfObjects.toString().startsWith("[Ljava.lang.Object;"));
+    }
+
+    @Test
+    public void givenInstanceOfArray_whenUsingArraysToStringToConvert_thenValueOfObjectsAreShown() {
+        Object[] arrayOfObjects = { "John", 2, true };
+        assertEquals(Arrays.toString(arrayOfObjects), "[John, 2, true]");
+    }
+
+    @Test
+    public void givenInstanceOfDeepArray_whenUsingArraysDeepToStringToConvert_thenValueOfInnerObjectsAreShown() {
+        Object[] innerArray = { "We", "Are", "Inside" };
+        Object[] arrayOfObjects = { "John", 2, innerArray };
+        assertEquals(Arrays.deepToString(arrayOfObjects), "[John, 2, [We, Are, Inside]]");
+    }
+
+    @Test
+    public void givenInstanceOfDeepArray_whenUsingStreamsToConvert_thenValueOfObjectsAreShown() {
+        Object[] arrayOfObjects = { "John", 2, true };
+        List<String> listOfString = Stream.of(arrayOfObjects)
+          .map(Object::toString)
+          .collect(Collectors.toList());
+        assertEquals(listOfString.toString(), "[John, 2, true]");
+    }
+}
@@ -9,3 +9,4 @@
 - [Differences Between Collection.clear() and Collection.removeAll()](https://www.baeldung.com/java-collection-clear-vs-removeall)
 - [Performance of contains() in a HashSet vs ArrayList](https://www.baeldung.com/java-hashset-arraylist-contains-performance)
 - [Fail-Safe Iterator vs Fail-Fast Iterator](https://www.baeldung.com/java-fail-safe-vs-fail-fast-iterator)
+- [Quick Guide to the Java Stack](https://www.baeldung.com/java-stack)
@@ -0,0 +1,66 @@
+package com.baeldung.abaproblem;
+
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class Account {
+
+    private AtomicInteger balance;
+    private AtomicInteger transactionCount;
+    private ThreadLocal<Integer> currentThreadCASFailureCount;
+
+    public Account() {
+        this.balance = new AtomicInteger(0);
+        this.transactionCount = new AtomicInteger(0);
+        this.currentThreadCASFailureCount = new ThreadLocal<>();
+        this.currentThreadCASFailureCount.set(0);
+    }
+
+    public int getBalance() {
+        return balance.get();
+    }
+
+    public int getTransactionCount() {
+        return transactionCount.get();
+    }
+
+    public int getCurrentThreadCASFailureCount() {
+        return currentThreadCASFailureCount.get();
+    }
+
+    public boolean withdraw(int amount) {
+        int current = getBalance();
+        maybeWait();
+        boolean result = balance.compareAndSet(current, current - amount);
+        if (result) {
+            transactionCount.incrementAndGet();
+        } else {
+            int currentCASFailureCount = currentThreadCASFailureCount.get();
+            currentThreadCASFailureCount.set(currentCASFailureCount + 1);
+        }
+        return result;
+    }
+
+    private void maybeWait() {
+        if ("thread1".equals(Thread.currentThread().getName())) {
+            try {
+                TimeUnit.SECONDS.sleep(2);
+            } catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+            }
+        }
+    }
+
+    public boolean deposit(int amount) {
+        int current = balance.get();
+        boolean result = balance.compareAndSet(current, current + amount);
+        if (result) {
+            transactionCount.incrementAndGet();
+        } else {
+            int currentCASFailureCount = currentThreadCASFailureCount.get();
+            currentThreadCASFailureCount.set(currentCASFailureCount + 1);
+        }
+        return result;
+    }
+
+}
@@ -9,13 +9,11 @@ public class StampedAccount {
    private AtomicStampedReference<Integer> account = new AtomicStampedReference<>(0, 0);

    public int getBalance() {
-        return this.account.get(new int[1]);
+        return account.getReference();
    }

    public int getStamp() {
-        int[] stamps = new int[1];
-        this.account.get(stamps);
-        return stamps[0];
+        return account.getStamp();
    }

    public boolean deposit(int funds) {
@@ -0,0 +1,98 @@
+package com.baeldung.abaproblem;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class AccountUnitTest {
+
+    private Account account;
+
+    @BeforeEach
+    public void setUp() {
+        account = new Account();
+    }
+
+    @Test
+    public void zeroBalanceInitializationTest() {
+        assertEquals(0, account.getBalance());
+        assertEquals(0, account.getTransactionCount());
+        assertEquals(0, account.getCurrentThreadCASFailureCount());
+    }
+
+    @Test
+    public void depositTest() {
+        final int moneyToDeposit = 50;
+
+        assertTrue(account.deposit(moneyToDeposit));
+
+        assertEquals(moneyToDeposit, account.getBalance());
+    }
+
+    @Test
+    public void withdrawTest() throws InterruptedException {
+        final int defaultBalance = 50;
+        final int moneyToWithdraw = 20;
+
+        account.deposit(defaultBalance);
+
+        assertTrue(account.withdraw(moneyToWithdraw));
+
+        assertEquals(defaultBalance - moneyToWithdraw, account.getBalance());
+    }
+
+    @Test
+    public void abaProblemTest() throws InterruptedException {
+        final int defaultBalance = 50;
+
+        final int amountToWithdrawByThread1 = 20;
+        final int amountToWithdrawByThread2 = 10;
+        final int amountToDepositByThread2 = 10;
+
+        assertEquals(0, account.getTransactionCount());
+        assertEquals(0, account.getCurrentThreadCASFailureCount());
+        account.deposit(defaultBalance);
+        assertEquals(1, account.getTransactionCount());
+
+        Thread thread1 = new Thread(() -> {
+
+            // this will take longer due to the name of the thread
+            assertTrue(account.withdraw(amountToWithdrawByThread1));
+
+            // thread 1 fails to capture ABA problem
+            assertNotEquals(1, account.getCurrentThreadCASFailureCount());
+
+        }, "thread1");
+
+        Thread thread2 = new Thread(() -> {
+
+            assertTrue(account.deposit(amountToDepositByThread2));
+            assertEquals(defaultBalance + amountToDepositByThread2, account.getBalance());
+
+            // this will be fast due to the name of the thread
+            assertTrue(account.withdraw(amountToWithdrawByThread2));
+
+            // thread 1 didn't finish yet, so the original value will be in place for it
+            assertEquals(defaultBalance, account.getBalance());
+
+            assertEquals(0, account.getCurrentThreadCASFailureCount());
+        }, "thread2");
+
+        thread1.start();
+        thread2.start();
+        thread1.join();
+        thread2.join();
+
+        // compareAndSet operation succeeds for thread 1
+        assertEquals(defaultBalance - amountToWithdrawByThread1, account.getBalance());
+
+        //but there are other transactions
+        assertNotEquals(2, account.getTransactionCount());
+
+        // thread 2 did two modifications as well
+        assertEquals(4, account.getTransactionCount());
+    }
+}
@@ -0,0 +1,5 @@
+#Core Java Console
+
+[Read and Write User Input in Java](http://www.baeldung.com/java-console-input-output)
+[Formatting with printf() in Java](https://www.baeldung.com/java-printstream-printf)
+[ASCII Art in Java](http://www.baeldung.com/ascii-art-in-java)
@@ -0,0 +1,142 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project
+    xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-console</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-console</name>
+    <packaging>jar</packaging>
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../</relativePath>
+    </parent>
+
+    <build>
+        <finalName>core-java-console</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-dependency-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <id>copy-dependencies</id>
+                        <phase>prepare-package</phase>
+                        <goals>
+                            <goal>copy-dependencies</goal>
+                        </goals>
+                        <configuration>
+                            <outputDirectory>${project.build.directory}/libs</outputDirectory>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>exec-maven-plugin</artifactId>
+                <version>${exec-maven-plugin.version}</version>
+                <configuration>
+                    <executable>java</executable>
+                    <mainClass>com.baeldung.outofmemoryerror.OutOfMemoryGCLimitExceed</mainClass>
+                    <arguments>
+                        <argument>-Xmx300m</argument>
+                        <argument>-XX:+UseParallelGC</argument>
+                        <argument>-classpath</argument>
+                        <classpath />
+                        <argument>com.baeldung.outofmemoryerror.OutOfMemoryGCLimitExceed</argument>
+                    </arguments>
+                </configuration>
+            </plugin>
+
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-javadoc-plugin</artifactId>
+                <version>${maven-javadoc-plugin.version}</version>
+                <configuration>
+                    <source>${source.version}</source>
+                    <target>${target.version}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <profiles>
+        <profile>
+            <id>integration</id>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-surefire-plugin</artifactId>
+                        <executions>
+                            <execution>
+                                <phase>integration-test</phase>
+                                <goals>
+                                    <goal>test</goal>
+                                </goals>
+                                <configuration>
+                                    <excludes>
+                                        <exclude>**/*ManualTest.java</exclude>
+                                    </excludes>
+                                    <includes>
+                                        <include>**/*IntegrationTest.java</include>
+                                        <include>**/*IntTest.java</include>
+                                    </includes>
+                                </configuration>
+                            </execution>
+                        </executions>
+                        <configuration>
+                            <systemPropertyVariables>
+                                <test.mime>json</test.mime>
+                            </systemPropertyVariables>
+                        </configuration>
+                    </plugin>
+                    <plugin>
+                        <groupId>org.codehaus.mojo</groupId>
+                        <artifactId>exec-maven-plugin</artifactId>
+                        <version>${exec-maven-plugin.version}</version>
+                        <executions>
+                            <execution>
+                                <id>run-benchmarks</id>
+                                <!-- <phase>integration-test</phase> -->
+                                <phase>none</phase>
+                                <goals>
+                                    <goal>exec</goal>
+                                </goals>
+                                <configuration>
+                                    <classpathScope>test</classpathScope>
+                                    <executable>java</executable>
+                                    <arguments>
+                                        <argument>-classpath</argument>
+                                        <classpath />
+                                        <argument>org.openjdk.jmh.Main</argument>
+                                        <argument>.*</argument>
+                                    </arguments>
+                                </configuration>
+                            </execution>
+                        </executions>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+    </profiles>
+
+    <properties>
+        <maven-javadoc-plugin.version>3.0.0-M1</maven-javadoc-plugin.version>
+        <exec-maven-plugin.version>1.6.0</exec-maven-plugin.version>
+        <source.version>1.8</source.version>
+        <target.version>1.8</target.version>
+    </properties>
+
+</project>
@@ -1,10 +1,9 @@
 package com.baeldung.asciiart;

-import java.awt.Font;
-
+import com.baeldung.asciiart.AsciiArt.Settings;
 import org.junit.Test;

-import com.baeldung.asciiart.AsciiArt.Settings;
+import java.awt.*;

 public class AsciiArtIntegrationTest {

@@ -16,5 +15,4 @@ public class AsciiArtIntegrationTest {
        
        asciiArt.drawString(text, "*", settings);
    }
-    
 }
@@ -8,4 +8,5 @@ This module contains articles about date operations in Java.
 - [Converting Java Date to OffsetDateTime](https://www.baeldung.com/java-convert-date-to-offsetdatetime)
 - [How to Set the JVM Time Zone](https://www.baeldung.com/java-jvm-time-zone)
 - [How to determine day of week by passing specific date in Java?](https://www.baeldung.com/java-get-day-of-week)
+- [Finding Leap Years in Java](https://www.baeldung.com/java-leap-year)
 - [[<-- Prev]](/core-java-modules/core-java-date-operations-1)
@@ -12,3 +12,4 @@ This module contains articles about working with the Java Virtual Machine (JVM).
 - [Guide to System.gc()](https://www.baeldung.com/java-system-gc)
 - [Runtime.getRuntime().halt() vs System.exit() in Java](https://www.baeldung.com/java-runtime-halt-vs-system-exit)
 - [Adding Shutdown Hooks for JVM Applications](https://www.baeldung.com/jvm-shutdown-hooks)
+- [How to Get the Size of an Object in Java](http://www.baeldung.com/java-size-of-object)
@@ -51,14 +51,31 @@
            <scope>system</scope>
            <systemPath>${java.home}/../lib/tools.jar</systemPath>
        </dependency>
+        <dependency>
+            <groupId>org.ow2.asm</groupId>
+            <artifactId>asm</artifactId>
+            <version>${asm.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.ow2.asm</groupId>
+            <artifactId>asm-util</artifactId>
+            <version>${asm.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.bcel</groupId>
+            <artifactId>bcel</artifactId>
+            <version>${bcel.version}</version>
+        </dependency>    
    </dependencies>

    <properties>
        <assertj.version>3.6.1</assertj.version>
        <!-- instrumentation -->
-        <javaassist.version>3.21.0-GA</javaassist.version>
+        <javaassist.version>3.27.0-GA</javaassist.version>
        <esapi.version>2.1.0.1</esapi.version>
        <sun.tools.version>1.8.0</sun.tools.version>
+        <asm.version>8.0.1</asm.version>
+        <bcel.version>6.5.0</bcel.version>
    </properties>

 </project>
--- a/Show More
+++ b/Show More