Merge pull request #3 from eugenp/master

Update from master
2018-02-17 23:19:09 +01:00
parent 2ddbff9858 2a127b3df3
commit 1f45a316cc
166 changed files with 4916 additions and 444 deletions
@@ -43,3 +43,4 @@ spring-call-getters-using-reflection/.mvn/wrapper/maven-wrapper.properties
 spring-check-if-a-property-is-null/.mvn/wrapper/maven-wrapper.properties
 *.springBeans

+20171220-JMeter.csv
@@ -0,0 +1,52 @@
+package com.baeldung.algorithms.maze.solver;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
+
+public class BFSMazeSolver {
+    private static final int[][] DIRECTIONS = { { 0, 1 }, { 1, 0 }, { 0, -1 }, { -1, 0 } };
+
+    public List<Coordinate> solve(Maze maze) {
+        LinkedList<Coordinate> nextToVisit = new LinkedList<>();
+        Coordinate start = maze.getEntry();
+        nextToVisit.add(start);
+
+        while (!nextToVisit.isEmpty()) {
+            Coordinate cur = nextToVisit.remove();
+
+            if (!maze.isValidLocation(cur.getX(), cur.getY()) || maze.isExplored(cur.getX(), cur.getY())) {
+                continue;
+            }
+
+            if (maze.isWall(cur.getX(), cur.getY())) {
+                maze.setVisited(cur.getX(), cur.getY(), true);
+                continue;
+            }
+
+            if (maze.isExit(cur.getX(), cur.getY())) {
+                return backtrackPath(cur);
+            }
+
+            for (int[] direction : DIRECTIONS) {
+                Coordinate coordinate = new Coordinate(cur.getX() + direction[0], cur.getY() + direction[1], cur);
+                nextToVisit.add(coordinate);
+                maze.setVisited(cur.getX(), cur.getY(), true);
+            }
+        }
+        return Collections.emptyList();
+    }
+
+    private List<Coordinate> backtrackPath(Coordinate cur) {
+        List<Coordinate> path = new ArrayList<>();
+        Coordinate iter = cur;
+
+        while (iter != null) {
+            path.add(iter);
+            iter = iter.parent;
+        }
+
+        return path;
+    }
+}
@@ -0,0 +1,31 @@
+package com.baeldung.algorithms.maze.solver;
+
+public class Coordinate {
+    int x;
+    int y;
+    Coordinate parent;
+
+    public Coordinate(int x, int y) {
+        this.x = x;
+        this.y = y;
+        this.parent = null;
+    }
+
+    public Coordinate(int x, int y, Coordinate parent) {
+        this.x = x;
+        this.y = y;
+        this.parent = parent;
+    }
+
+    int getX() {
+        return x;
+    }
+
+    int getY() {
+        return y;
+    }
+
+    Coordinate getParent() {
+        return parent;
+    }
+}
@@ -0,0 +1,48 @@
+package com.baeldung.algorithms.maze.solver;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class DFSMazeSolver {
+    private static final int[][] DIRECTIONS = { { 0, 1 }, { 1, 0 }, { 0, -1 }, { -1, 0 } };
+
+    public List<Coordinate> solve(Maze maze) {
+        List<Coordinate> path = new ArrayList<>();
+        if (explore(maze, maze.getEntry()
+            .getX(),
+            maze.getEntry()
+                .getY(),
+            path)) {
+            return path;
+        }
+        return Collections.emptyList();
+    }
+
+    private boolean explore(Maze maze, int row, int col, List<Coordinate> path) {
+        if (!maze.isValidLocation(row, col) || maze.isWall(row, col) || maze.isExplored(row, col)) {
+            return false;
+        }
+
+        path.add(new Coordinate(row, col));
+        maze.setVisited(row, col, true);
+
+        if (maze.isExit(row, col)) {
+            return true;
+        }
+
+        for (int[] direction : DIRECTIONS) {
+            Coordinate coordinate = getNextCoordinate(row, col, direction[0], direction[1]);
+            if (explore(maze, coordinate.getX(), coordinate.getY(), path)) {
+                return true;
+            }
+        }
+
+        path.remove(path.size() - 1);
+        return false;
+    }
+
+    private Coordinate getNextCoordinate(int row, int col, int i, int j) {
+        return new Coordinate(row + i, col + j);
+    }
+}
@@ -0,0 +1,141 @@
+package com.baeldung.algorithms.maze.solver;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Scanner;
+
+public class Maze {
+    private static final int ROAD = 0;
+    private static final int WALL = 1;
+    private static final int START = 2;
+    private static final int EXIT = 3;
+    private static final int PATH = 4;
+
+    private int[][] maze;
+    private boolean[][] visited;
+    private Coordinate start;
+    private Coordinate end;
+
+    public Maze(File maze) throws FileNotFoundException {
+        String fileText = "";
+        try (Scanner input = new Scanner(maze)) {
+            while (input.hasNextLine()) {
+                fileText += input.nextLine() + "\n";
+            }
+        }
+        initializeMaze(fileText);
+    }
+
+    private void initializeMaze(String text) {
+        if (text == null || (text = text.trim()).length() == 0) {
+            throw new IllegalArgumentException("empty lines data");
+        }
+
+        String[] lines = text.split("[\r]?\n");
+        maze = new int[lines.length][lines[0].length()];
+        visited = new boolean[lines.length][lines[0].length()];
+
+        for (int row = 0; row < getHeight(); row++) {
+            if (lines[row].length() != getWidth()) {
+                throw new IllegalArgumentException("line " + (row + 1) + " wrong length (was " + lines[row].length() + " but should be " + getWidth() + ")");
+            }
+
+            for (int col = 0; col < getWidth(); col++) {
+                if (lines[row].charAt(col) == '#')
+                    maze[row][col] = WALL;
+                else if (lines[row].charAt(col) == 'S') {
+                    maze[row][col] = START;
+                    start = new Coordinate(row, col);
+                } else if (lines[row].charAt(col) == 'E') {
+                    maze[row][col] = EXIT;
+                    end = new Coordinate(row, col);
+                } else
+                    maze[row][col] = ROAD;
+            }
+        }
+    }
+
+    public int getHeight() {
+        return maze.length;
+    }
+
+    public int getWidth() {
+        return maze[0].length;
+    }
+
+    public Coordinate getEntry() {
+        return start;
+    }
+
+    public Coordinate getExit() {
+        return end;
+    }
+
+    public boolean isExit(int x, int y) {
+        return x == end.getX() && y == end.getY();
+    }
+
+    public boolean isStart(int x, int y) {
+        return x == start.getX() && y == start.getY();
+    }
+
+    public boolean isExplored(int row, int col) {
+        return visited[row][col];
+    }
+
+    public boolean isWall(int row, int col) {
+        return maze[row][col] == WALL;
+    }
+
+    public void setVisited(int row, int col, boolean value) {
+        visited[row][col] = value;
+    }
+
+    public boolean isValidLocation(int row, int col) {
+        if (row < 0 || row >= getHeight() || col < 0 || col >= getWidth()) {
+            return false;
+        }
+        return true;
+    }
+
+    public void printPath(List<Coordinate> path) {
+        int[][] tempMaze = Arrays.stream(maze)
+            .map(int[]::clone)
+            .toArray(int[][]::new);
+        for (Coordinate coordinate : path) {
+            if (isStart(coordinate.getX(), coordinate.getY()) || isExit(coordinate.getX(), coordinate.getY())) {
+                continue;
+            }
+            tempMaze[coordinate.getX()][coordinate.getY()] = PATH;
+        }
+        System.out.println(toString(tempMaze));
+    }
+
+    public String toString(int[][] maze) {
+        StringBuilder result = new StringBuilder(getWidth() * (getHeight() + 1));
+        for (int row = 0; row < getHeight(); row++) {
+            for (int col = 0; col < getWidth(); col++) {
+                if (maze[row][col] == ROAD) {
+                    result.append(' ');
+                } else if (maze[row][col] == WALL) {
+                    result.append('#');
+                } else if (maze[row][col] == START) {
+                    result.append('S');
+                } else if (maze[row][col] == EXIT) {
+                    result.append('E');
+                } else {
+                    result.append('.');
+                }
+            }
+            result.append('\n');
+        }
+        return result.toString();
+    }
+
+    public void reset() {
+        for (int i = 0; i < visited.length; i++)
+            Arrays.fill(visited[i], false);
+    }
+}
@@ -0,0 +1,34 @@
+package com.baeldung.algorithms.maze.solver;
+
+import java.io.File;
+import java.util.List;
+
+public class MazeDriver {
+    public static void main(String[] args) throws Exception {
+        File maze1 = new File("src/main/resources/maze/maze1.txt");
+        File maze2 = new File("src/main/resources/maze/maze2.txt");
+
+        execute(maze1);
+        execute(maze2);
+    }
+
+    private static void execute(File file) throws Exception {
+        Maze maze = new Maze(file);
+        dfs(maze);
+        bfs(maze);
+    }
+
+    private static void bfs(Maze maze) {
+        BFSMazeSolver bfs = new BFSMazeSolver();
+        List<Coordinate> path = bfs.solve(maze);
+        maze.printPath(path);
+        maze.reset();
+    }
+
+    private static void dfs(Maze maze) {
+        DFSMazeSolver dfs = new DFSMazeSolver();
+        List<Coordinate> path = dfs.solve(maze);
+        maze.printPath(path);
+        maze.reset();
+    }
+}
@@ -40,15 +40,15 @@ public class BacktrackingAlgorithm {
    }

    private boolean solve(int[][] board) {
-        for (int r = BOARD_START_INDEX; r < BOARD_SIZE; r++) {
-            for (int c = BOARD_START_INDEX; c < BOARD_SIZE; c++) {
-                if (board[r][c] == NO_VALUE) {
+        for (int row = BOARD_START_INDEX; row < BOARD_SIZE; row++) {
+            for (int column = BOARD_START_INDEX; column < BOARD_SIZE; column++) {
+                if (board[row][column] == NO_VALUE) {
                    for (int k = MIN_VALUE; k <= MAX_VALUE; k++) {
-                        board[r][c] = k;
-                        if (isValid(board, r, c) && solve(board)) {
+                        board[row][column] = k;
+                        if (isValid(board, row, column) && solve(board)) {
                            return true;
                        }
-                        board[r][c] = NO_VALUE;
+                        board[row][column] = NO_VALUE;
                    }
                    return false;
                }
@@ -57,48 +57,48 @@ public class BacktrackingAlgorithm {
        return true;
    }

-    private boolean isValid(int[][] board, int r, int c) {
-        return rowConstraint(board, r) &&
-          columnConstraint(board, c) &&
-          subsectionConstraint(board, r, c);
+    private boolean isValid(int[][] board, int row, int column) {
+        return rowConstraint(board, row) &&
+          columnConstraint(board, column) &&
+          subsectionConstraint(board, row, column);
    }

-    private boolean subsectionConstraint(int[][] board, int r, int c) {
+    private boolean subsectionConstraint(int[][] board, int row, int column) {
        boolean[] constraint = new boolean[BOARD_SIZE];
-        int subsectionRowStart = (r / SUBSECTION_SIZE) * SUBSECTION_SIZE;
+        int subsectionRowStart = (row / SUBSECTION_SIZE) * SUBSECTION_SIZE;
        int subsectionRowEnd = subsectionRowStart + SUBSECTION_SIZE;

-        int subsectionColumnStart = (c / SUBSECTION_SIZE) * SUBSECTION_SIZE;
+        int subsectionColumnStart = (column / SUBSECTION_SIZE) * SUBSECTION_SIZE;
        int subsectionColumnEnd = subsectionColumnStart + SUBSECTION_SIZE;

-        for (int i = subsectionRowStart; i < subsectionRowEnd; i++) {
-            for (int j = subsectionColumnStart; j < subsectionColumnEnd; j++) {
-                if (!checkConstraint(board, i, constraint, j)) return false;
+        for (int r = subsectionRowStart; r < subsectionRowEnd; r++) {
+            for (int c = subsectionColumnStart; c < subsectionColumnEnd; c++) {
+                if (!checkConstraint(board, r, constraint, c)) return false;
            }
        }
        return true;
    }

-    private boolean columnConstraint(int[][] board, int c) {
+    private boolean columnConstraint(int[][] board, int column) {
        boolean[] constraint = new boolean[BOARD_SIZE];
        return IntStream.range(BOARD_START_INDEX, BOARD_SIZE)
-          .allMatch(i -> checkConstraint(board, i, constraint, c));
+          .allMatch(row -> checkConstraint(board, row, constraint, column));
    }

-    private boolean rowConstraint(int[][] board, int r) {
+    private boolean rowConstraint(int[][] board, int row) {
        boolean[] constraint = new boolean[BOARD_SIZE];
        return IntStream.range(BOARD_START_INDEX, BOARD_SIZE)
-          .allMatch(i -> checkConstraint(board, r, constraint, i));
+          .allMatch(column -> checkConstraint(board, row, constraint, column));
    }

-    private boolean checkConstraint(int[][] board, int r, boolean[] constraint, int c) {
-        if (board[r][c] != NO_VALUE) {
-            if (!constraint[board[r][c] - 1]) {
-                constraint[board[r][c] - 1] = true;
+    private boolean checkConstraint(int[][] board, int row, boolean[] constraint, int column) {
+        if (board[row][column] != NO_VALUE) {
+            if (!constraint[board[row][column] - 1]) {
+                constraint[board[row][column] - 1] = true;
            } else {
                return false;
            }
        }
        return true;
    }
-}
+}
@@ -120,10 +120,10 @@ public class DancingLinks {
    }

    private static void printSolution(int[][] result) {
-        int N = result.length;
+        int size = result.length;
        for (int[] aResult : result) {
            StringBuilder ret = new StringBuilder();
-            for (int j = 0; j < N; j++) {
+            for (int j = 0; j < size; j++) {
                ret.append(aResult[j]).append(" ");
            }
            System.out.println(ret);
@@ -34,75 +34,88 @@ public class DancingLinksAlgorithm {
        dlx.runSolver();
    }

-    private int getIndex(int row, int col, int num) {
-        return (row - 1) * BOARD_SIZE * BOARD_SIZE + (col - 1) * BOARD_SIZE + (num - 1);
+    private int getIndex(int row, int column, int num) {
+        return (row - 1) * BOARD_SIZE * BOARD_SIZE + (column - 1) * BOARD_SIZE + (num - 1);
    }

    private boolean[][] createExactCoverBoard() {
-        boolean[][] R = new boolean[BOARD_SIZE * BOARD_SIZE * MAX_VALUE][BOARD_SIZE * BOARD_SIZE * CONSTRAINTS];
+        boolean[][] coverBoard = new boolean[BOARD_SIZE * BOARD_SIZE * MAX_VALUE][BOARD_SIZE * BOARD_SIZE * CONSTRAINTS];

        int hBase = 0;
+        hBase = checkCellConstraint(coverBoard, hBase);
+        hBase = checkRowConstraint(coverBoard, hBase);
+        hBase = checkColumnConstraint(coverBoard, hBase);
+        checkSubsectionConstraint(coverBoard, hBase);
+        
+        return coverBoard;
+    }

-        // Cell constraint.
-        for (int r = COVER_START_INDEX; r <= BOARD_SIZE; r++) {
-            for (int c = COVER_START_INDEX; c <= BOARD_SIZE; c++, hBase++) {
-                for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++) {
-                    int index = getIndex(r, c, n);
-                    R[index][hBase] = true;
-                }
-            }
-        }
-
-        // Row constrain.
-        for (int r = COVER_START_INDEX; r <= BOARD_SIZE; r++) {
-            for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++, hBase++) {
-                for (int c1 = COVER_START_INDEX; c1 <= BOARD_SIZE; c1++) {
-                    int index = getIndex(r, c1, n);
-                    R[index][hBase] = true;
-                }
-            }
-        }
-
-        // Column constraint.
-        for (int c = COVER_START_INDEX; c <= BOARD_SIZE; c++) {
-            for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++, hBase++) {
-                for (int r1 = COVER_START_INDEX; r1 <= BOARD_SIZE; r1++) {
-                    int index = getIndex(r1, c, n);
-                    R[index][hBase] = true;
-                }
-            }
-        }
-
-        // Subsection constraint
-        for (int br = COVER_START_INDEX; br <= BOARD_SIZE; br += SUBSECTION_SIZE) {
-            for (int bc = COVER_START_INDEX; bc <= BOARD_SIZE; bc += SUBSECTION_SIZE) {
+    private int checkSubsectionConstraint(boolean[][] coverBoard, int hBase) {
+        for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row += SUBSECTION_SIZE) {
+            for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column += SUBSECTION_SIZE) {
                for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++, hBase++) {
-                    for (int rDelta = 0; rDelta < SUBSECTION_SIZE; rDelta++) {
-                        for (int cDelta = 0; cDelta < SUBSECTION_SIZE; cDelta++) {
-                            int index = getIndex(br + rDelta, bc + cDelta, n);
-                            R[index][hBase] = true;
+                    for (int rowDelta = 0; rowDelta < SUBSECTION_SIZE; rowDelta++) {
+                        for (int columnDelta = 0; columnDelta < SUBSECTION_SIZE; columnDelta++) {
+                            int index = getIndex(row + rowDelta, column + columnDelta, n);
+                            coverBoard[index][hBase] = true;
                        }
                    }
                }
            }
        }
-        return R;
+        return hBase;
+    }
+
+    private int checkColumnConstraint(boolean[][] coverBoard, int hBase) {
+        for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column++) {
+            for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++, hBase++) {
+                for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row++) {
+                    int index = getIndex(row, column, n);
+                    coverBoard[index][hBase] = true;
+                }
+            }
+        }
+        return hBase;
+    }
+
+    private int checkRowConstraint(boolean[][] coverBoard, int hBase) {
+        for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row++) {
+            for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++, hBase++) {
+                for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column++) {
+                    int index = getIndex(row, column, n);
+                    coverBoard[index][hBase] = true;
+                }
+            }
+        }
+        return hBase;
+    }
+
+    private int checkCellConstraint(boolean[][] coverBoard, int hBase) {
+        for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row++) {
+            for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column++, hBase++) {
+                for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++) {
+                    int index = getIndex(row, column, n);
+                    coverBoard[index][hBase] = true;
+                }
+            }
+        }
+        return hBase;
    }

    private boolean[][] initializeExactCoverBoard(int[][] board) {
-        boolean[][] R = createExactCoverBoard();
-        for (int i = COVER_START_INDEX; i <= BOARD_SIZE; i++) {
-            for (int j = COVER_START_INDEX; j <= BOARD_SIZE; j++) {
-                int n = board[i - 1][j - 1];
+        boolean[][] coverBoard = createExactCoverBoard();
+        for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row++) {
+            for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column++) {
+                int n = board[row - 1][column - 1];
                if (n != NO_VALUE) {
                    for (int num = MIN_VALUE; num <= MAX_VALUE; num++) {
                        if (num != n) {
-                            Arrays.fill(R[getIndex(i, j, num)], false);
+                            Arrays.fill(coverBoard[getIndex(row, column, num)], false);
                        }
                    }
                }
            }
        }
-        return R;
+        return coverBoard;
    }
 }
@@ -4,21 +4,21 @@ class DancingNode {
    DancingNode L, R, U, D;
    ColumnNode C;

-    DancingNode hookDown(DancingNode n1) {
-        assert (this.C == n1.C);
-        n1.D = this.D;
-        n1.D.U = n1;
-        n1.U = this;
-        this.D = n1;
-        return n1;
+    DancingNode hookDown(DancingNode node) {
+        assert (this.C == node.C);
+        node.D = this.D;
+        node.D.U = node;
+        node.U = this;
+        this.D = node;
+        return node;
    }

-    DancingNode hookRight(DancingNode n1) {
-        n1.R = this.R;
-        n1.R.L = n1;
-        n1.L = this;
-        this.R = n1;
-        return n1;
+    DancingNode hookRight(DancingNode node) {
+        node.R = this.R;
+        node.R.L = node;
+        node.L = this;
+        this.R = node;
+        return node;
    }

    void unlinkLR() {
@@ -0,0 +1,12 @@
+S ########
+#        #
+# ### ## #
+# #    # #
+# #  # # #
+# ## #####
+# #      #
+# # #  # #
+##### ####
+#   #    E
+# #    # #
+##########
@@ -0,0 +1,22 @@
+S ##########################
+# #      #                 #
+# # ####   ############### #
+# # #    # #               #
+# # #### # # ###############
+# # #    # # #             #
+# # # #### ### ########### #
+# # # #        #           #
+#       ################## #
+#########    # # #       # #
+# #       #### # ####### # #
+# # ### ###  # # #       # #
+#   #       ##   # ##### # #
+##### #######  # #     # # #
+#     #       ## ## #### # #
+# ##### #######     #      #
+#       #       ############
+####### #########        # #
+#       #         ######## #
+# ####### ###### ##   #    E
+#         #         #   ## #
+############################
@@ -0,0 +1,70 @@
+package com.baeldung.shufflingcollections;
+
+import org.junit.Test;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class ShufflingCollectionsUnitTest {
+
+    @Test
+    public void whenShufflingList_thenListIsShuffled() {
+        List<String> students = Arrays.asList("Foo", "Bar", "Baz", "Qux");
+
+        System.out.println("List before shuffling:");
+        System.out.println(students);
+
+        Collections.shuffle(students);
+        System.out.println("List after shuffling:");
+        System.out.println(students);
+    }
+
+    @Test
+    public void whenShufflingMapKeys_thenValuesAreShuffled() {
+        Map<Integer, String> studentsById = new HashMap<>();
+        studentsById.put(1, "Foo");
+        studentsById.put(2, "Bar");
+        studentsById.put(3, "Baz");
+        studentsById.put(4, "Qux");
+
+        System.out.println("Students before shuffling:");
+        System.out.println(studentsById.values());
+
+        List<Integer> shuffledStudentIds = new ArrayList<>(studentsById.keySet());
+        Collections.shuffle(shuffledStudentIds);
+
+        List<String> shuffledStudents = shuffledStudentIds.stream()
+          .map(id -> studentsById.get(id))
+          .collect(Collectors.toList());
+
+        System.out.println("Students after shuffling");
+        System.out.println(shuffledStudents);
+    }
+
+    @Test
+    public void whenShufflingSet_thenElementsAreShuffled() {
+        Set<String> students = new HashSet<>(Arrays.asList("Foo", "Bar", "Baz", "Qux"));
+
+        System.out.println("Set before shuffling:");
+        System.out.println(students);
+
+        List<String> studentList = new ArrayList<>(students);
+
+        Collections.shuffle(studentList);
+        System.out.println("Shuffled set elements:");
+        System.out.println(studentList);
+    }
+
+    @Test
+    public void whenShufflingWithSameRandomness_thenElementsAreShuffledDeterministically() {
+        List<String> students_1 = Arrays.asList("Foo", "Bar", "Baz", "Qux");
+        List<String> students_2 = Arrays.asList("Foo", "Bar", "Baz", "Qux");
+
+        Collections.shuffle(students_1, new Random(5));
+        Collections.shuffle(students_2, new Random(5));
+
+        assertThat(students_1).isEqualTo(students_2);
+    }
+}
@@ -1,126 +0,0 @@
-package com.baeldung.java9.httpclient;
-
-import static java.net.HttpURLConnection.HTTP_OK;
-import static org.junit.Assert.assertTrue;
-
-import java.io.IOException;
-import java.net.CookieManager;
-import java.net.CookiePolicy;
-import java.net.URI;
-import java.net.URISyntaxException;
-import java.net.http.HttpClient;
-import java.net.http.HttpHeaders;
-import java.net.http.HttpRequest;
-import java.net.http.HttpResponse;
-import java.security.NoSuchAlgorithmException;
-import java.util.List;
-import java.util.Map;
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.ExecutionException;
-
-import javax.net.ssl.SSLContext;
-import javax.net.ssl.SSLParameters;
-
-import org.junit.Before;
-import org.junit.Test;
-
-public class SimpleHttpRequestsUnitTest {
-
-    private URI httpURI;
-
-    @Before
-    public void init() throws URISyntaxException {
-        httpURI = new URI("http://www.baeldung.com/");
-    }
-
-    @Test
-    public void quickGet() throws IOException, InterruptedException, URISyntaxException {
-        HttpRequest request = HttpRequest.create(httpURI).GET();
-        HttpResponse response = request.response();
-        int responseStatusCode = response.statusCode();
-        String responseBody = response.body(HttpResponse.asString());
-        assertTrue("Get response status code is bigger then 400", responseStatusCode < 400);
-    }
-
-    @Test
-    public void asynchronousGet() throws URISyntaxException, IOException, InterruptedException, ExecutionException {
-        HttpRequest request = HttpRequest.create(httpURI).GET();
-        long before = System.currentTimeMillis();
-        CompletableFuture<HttpResponse> futureResponse = request.responseAsync();
-        futureResponse.thenAccept(response -> {
-            String responseBody = response.body(HttpResponse.asString());
-        });
-        HttpResponse resp = futureResponse.get();
-        HttpHeaders hs = resp.headers();
-        assertTrue("There should be more then 1 header.", hs.map().size() > 1);
-    }
-
-    @Test
-    public void postMehtod() throws URISyntaxException, IOException, InterruptedException {
-        HttpRequest.Builder requestBuilder = HttpRequest.create(httpURI);
-        requestBuilder.body(HttpRequest.fromString("param1=foo,param2=bar")).followRedirects(HttpClient.Redirect.SECURE);
-        HttpRequest request = requestBuilder.POST();
-        HttpResponse response = request.response();
-        int statusCode = response.statusCode();
-        assertTrue("HTTP return code", statusCode == HTTP_OK);
-    }
-
-    @Test
-    public void configureHttpClient() throws NoSuchAlgorithmException, URISyntaxException, IOException, InterruptedException {
-        CookieManager cManager = new CookieManager();
-        cManager.setCookiePolicy(CookiePolicy.ACCEPT_ORIGINAL_SERVER);
-
-        SSLParameters sslParam = new SSLParameters(new String[] { "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256" }, new String[] { "TLSv1.2" });
-
-        HttpClient.Builder hcBuilder = HttpClient.create();
-        hcBuilder.cookieManager(cManager).sslContext(SSLContext.getDefault()).sslParameters(sslParam);
-        HttpClient httpClient = hcBuilder.build();
-        HttpRequest.Builder reqBuilder = httpClient.request(new URI("https://www.facebook.com"));
-
-        HttpRequest request = reqBuilder.followRedirects(HttpClient.Redirect.ALWAYS).GET();
-        HttpResponse response = request.response();
-        int statusCode = response.statusCode();
-        assertTrue("HTTP return code", statusCode == HTTP_OK);
-    }
-
-    SSLParameters getDefaultSSLParameters() throws NoSuchAlgorithmException {
-        SSLParameters sslP1 = SSLContext.getDefault().getSupportedSSLParameters();
-        String[] proto = sslP1.getApplicationProtocols();
-        String[] cifers = sslP1.getCipherSuites();
-        System.out.println(printStringArr(proto));
-        System.out.println(printStringArr(cifers));
-        return sslP1;
-    }
-
-    String printStringArr(String... args) {
-        if (args == null) {
-            return null;
-        }
-        StringBuilder sb = new StringBuilder();
-        for (String s : args) {
-            sb.append(s);
-            sb.append("\n");
-        }
-        return sb.toString();
-    }
-
-    String printHeaders(HttpHeaders h) {
-        if (h == null) {
-            return null;
-        }
-
-        StringBuilder sb = new StringBuilder();
-        Map<String, List<String>> hMap = h.map();
-        for (String k : hMap.keySet()) {
-            sb.append(k).append(":");
-            List<String> l = hMap.get(k);
-            if (l != null) {
-                l.forEach(s -> {
-                    sb.append(s).append(",");
-                });
-            }
-            sb.append("\n");
-        }
-        return sb.toString();
-    }
-}
@@ -16,7 +16,8 @@ public class Job implements Runnable {
    @Override
    public void run() {
        try {
-            System.out.println("Job:" + jobName + " Priority:" + jobPriority);
+            System.out.println("Job:" + jobName + 
+              " Priority:" + jobPriority);
            Thread.sleep(1000);
        } catch (InterruptedException ignored) {
        }
@@ -9,21 +9,21 @@ import java.util.concurrent.TimeUnit;
 public class PriorityJobScheduler {

    private ExecutorService priorityJobPoolExecutor;
-    private ExecutorService priorityJobScheduler;
-    private PriorityBlockingQueue<Runnable> priorityQueue;
+    private ExecutorService priorityJobScheduler = 
+      Executors.newSingleThreadExecutor();
+    private PriorityBlockingQueue<Job> priorityQueue;

    public PriorityJobScheduler(Integer poolSize, Integer queueSize) {
        priorityJobPoolExecutor = Executors.newFixedThreadPool(poolSize);
-        Comparator<? super Job> jobComparator = Comparator.comparing(Job::getJobPriority);
-        priorityQueue = new PriorityBlockingQueue<Runnable>(queueSize, 
-          (Comparator<? super Runnable>) jobComparator);
+        priorityQueue = new PriorityBlockingQueue<Job>(queueSize, 
+          Comparator.comparing(Job::getJobPriority));

-        priorityJobScheduler = Executors.newSingleThreadExecutor();
        priorityJobScheduler.execute(()->{
            while (true) {
                try {
                    priorityJobPoolExecutor.execute(priorityQueue.take());
                } catch (InterruptedException e) {
+                    // exception needs special handling
                    break;
                }
            }
@@ -0,0 +1,31 @@
+package com.baeldung.concurrent.threadlifecycle;
+
+public class BlockedState {
+    public static void main(String[] args) throws InterruptedException {
+        Thread t1 = new Thread(new DemoThreadB());
+        Thread t2 = new Thread(new DemoThreadB());
+        
+        t1.start();
+        t2.start();
+        
+        Thread.sleep(1000);
+        
+        System.out.println(t2.getState());
+        System.exit(0);
+    }
+}
+
+class DemoThreadB implements Runnable {
+    @Override
+    public void run() {
+        commonResource();
+    }
+    
+    public static synchronized void commonResource() {
+        while(true) {
+            // Infinite loop to mimic heavy processing
+            // Thread 't1' won't leave this method
+            // when Thread 't2' enters this
+        }
+    }
+}
@@ -0,0 +1,14 @@
+package com.baeldung.concurrent.threadlifecycle;
+
+public class NewState implements Runnable {
+    public static void main(String[] args) {
+        Runnable runnable = new NewState();
+        Thread t = new Thread(runnable);
+        System.out.println(t.getState());
+    }
+    
+    @Override
+    public void run() {
+        
+    }
+}
@@ -0,0 +1,15 @@
+package com.baeldung.concurrent.threadlifecycle;
+
+public class RunnableState implements Runnable {
+    public static void main(String[] args) {
+        Runnable runnable = new NewState();
+        Thread t = new Thread(runnable);
+        t.start();
+        System.out.println(t.getState());
+    }
+    
+    @Override
+    public void run() {
+        
+    }
+}
@@ -0,0 +1,15 @@
+package com.baeldung.concurrent.threadlifecycle;
+
+public class TerminatedState implements Runnable {
+    public static void main(String[] args) throws InterruptedException {
+        Thread t1 = new Thread(new TerminatedState());
+        t1.start();
+        Thread.sleep(1000);
+        System.out.println(t1.getState());
+    }
+    
+    @Override
+    public void run() {
+        // No processing in this block
+    }
+}
@@ -0,0 +1,25 @@
+package com.baeldung.concurrent.threadlifecycle;
+
+public class TimedWaitingState {
+    public static void main(String[] args) throws InterruptedException {
+        DemoThread obj1 = new DemoThread();
+        Thread t1 = new Thread(obj1);
+        t1.start();
+        // The following sleep will give enough time for ThreadScheduler
+        // to start processing of thread t1
+        Thread.sleep(1000);
+        System.out.println(t1.getState());
+    }
+}
+
+class DemoThread implements Runnable {
+    @Override
+    public void run() {
+        try {
+            Thread.sleep(5000);
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            e.printStackTrace();
+        }
+    }
+}
@@ -0,0 +1,35 @@
+package com.baeldung.concurrent.threadlifecycle;
+
+public class WaitingState implements Runnable {
+    public static Thread t1;
+
+    public static void main(String[] args) {
+        t1 = new Thread(new WaitingState());
+        t1.start();
+    }
+
+    public void run() {
+        Thread t2 = new Thread(new DemoThreadWS());
+        t2.start();
+
+        try {
+            t2.join();
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            e.printStackTrace();
+        }
+    }
+}
+
+class DemoThreadWS implements Runnable {
+    public void run() {
+        try {
+            Thread.sleep(1000);
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            e.printStackTrace();
+        }
+        
+        System.out.println(WaitingState.t1.getState());
+    }
+}
@@ -30,7 +30,9 @@ public class PriorityJobSchedulerUnitTest {
        // delay to avoid job sleep (added for demo) being interrupted
        try {
            Thread.sleep(2000);
-        } catch (InterruptedException ignored) {
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            throw new RuntimeException(e);
        }
        
        pjs.closeScheduler();
@@ -0,0 +1,26 @@
+package com.baeldung.methodoverloadingoverriding.application;
+
+import com.baeldung.methodoverloadingoverriding.model.Car;
+import com.baeldung.methodoverloadingoverriding.model.Vehicle;
+import com.baeldung.methodoverloadingoverriding.util.Multiplier;
+
+public class Application {
+    
+    public static void main(String[] args) {
+        Multiplier multiplier = new Multiplier();
+        System.out.println(multiplier.multiply(10, 10));
+        System.out.println(multiplier.multiply(10, 10, 10));
+        System.out.println(multiplier.multiply(10, 10.5));
+        System.out.println(multiplier.multiply(10.5, 10.5));
+        
+        Vehicle vehicle = new Vehicle();
+        System.out.println(vehicle.accelerate(100));
+        System.out.println(vehicle.run());
+        System.out.println(vehicle.stop());
+        
+        Vehicle car = new Car();
+        System.out.println(car.accelerate(80));
+        System.out.println(car.run());
+        System.out.println(car.stop());
+    }
+}
@@ -0,0 +1,9 @@
+package com.baeldung.methodoverloadingoverriding.model;
+
+public class Car extends Vehicle {
+
+    @Override
+    public String accelerate(long mph) {
+        return "The car accelerates at : " + mph + " MPH.";
+    }
+}
@@ -0,0 +1,16 @@
+package com.baeldung.methodoverloadingoverriding.model;
+
+public class Vehicle {
+    
+    public String accelerate(long mph) {
+        return "The vehicle accelerates at : " + mph + " MPH.";
+    }
+    
+    public String stop() {
+        return "The vehicle has stopped.";
+    }
+    
+    public String run() {
+        return "The vehicle is running.";
+    }
+}
@@ -0,0 +1,16 @@
+package com.baeldung.methodoverloadingoverriding.util;
+
+public class Multiplier {
+    
+    public int multiply(int a, int b) {
+        return a * b;
+    }
+    
+    public int multiply(int a, int b, int c) {
+        return a * b * c;
+    }
+    
+    public double multiply(double a, double b) {
+        return a * b;
+    }
+}
@@ -0,0 +1,66 @@
+package com.baeldung.string;
+
+import java.util.stream.IntStream;
+
+public class Palindrome {
+
+    public boolean isPalindrome(String text) {
+        String clean = text.replaceAll("\\s+", "").toLowerCase();
+        int length = clean.length();
+        int forward = 0;
+        int backward = length - 1;
+        while (backward > forward) {
+            char forwardChar = clean.charAt(forward++);
+            char backwardChar = clean.charAt(backward--);
+            if (forwardChar != backwardChar)
+                return false;
+        }
+        return true;
+    }
+
+    public boolean isPalindromeReverseTheString(String text) {
+        StringBuilder reverse = new StringBuilder();
+        String clean = text.replaceAll("\\s+", "").toLowerCase();
+        char[] plain = clean.toCharArray();
+        for (int i = plain.length - 1; i >= 0; i--)
+            reverse.append(plain[i]);
+        return (reverse.toString()).equals(clean);
+    }
+
+    public boolean isPalindromeUsingStringBuilder(String text) {
+        String clean = text.replaceAll("\\s+", "").toLowerCase();
+        StringBuilder plain = new StringBuilder(clean);
+        StringBuilder reverse = plain.reverse();
+        return (reverse.toString()).equals(clean);
+    }
+
+    public boolean isPalindromeUsingStringBuffer(String text) {
+        String clean = text.replaceAll("\\s+", "").toLowerCase();
+        StringBuffer plain = new StringBuffer(clean);
+        StringBuffer reverse = plain.reverse();
+        return (reverse.toString()).equals(clean);
+    }
+
+    public boolean isPalindromeRecursive(String text) {
+        String clean = text.replaceAll("\\s+", "").toLowerCase();
+        return recursivePalindrome(clean, 0, clean.length() - 1);
+    }
+
+    private boolean recursivePalindrome(String text, int forward, int backward) {
+        if (forward == backward)
+            return true;
+        if ((text.charAt(forward)) != (text.charAt(backward)))
+            return false;
+        if (forward < backward + 1) {
+            return recursivePalindrome(text, forward + 1, backward - 1);
+        }
+
+        return true;
+    }
+
+    public boolean isPalindromeUsingIntStream(String text) {
+        String temp = text.replaceAll("\\s+", "").toLowerCase();
+        return IntStream.range(0, temp.length() / 2)
+            .noneMatch(i -> temp.charAt(i) != temp.charAt(temp.length() - i - 1));
+    }
+}
@@ -0,0 +1,116 @@
+package com.baeldung.decimalformat;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.math.BigDecimal;
+import java.text.DecimalFormat;
+import java.text.DecimalFormatSymbols;
+import java.text.NumberFormat;
+import java.text.ParseException;
+import java.util.Locale;
+
+import org.junit.Test;
+
+public class DecimalFormatExamplesTest {
+
+	double d = 1234567.89;
+
+	@Test
+	public void givenSimpleDecimal_WhenFormatting_ThenCorrectOutput() {
+
+		assertThat(new DecimalFormat("#.##", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
+				.isEqualTo("1234567.89");
+
+		assertThat(new DecimalFormat("0.00", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
+				.isEqualTo("1234567.89");
+
+		assertThat(new DecimalFormat("#########.###", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
+				.isEqualTo("1234567.89");
+
+		assertThat(new DecimalFormat("000000000.000", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
+				.isEqualTo("001234567.890");
+
+	}
+
+	@Test
+	public void givenSmallerDecimalPattern_WhenFormatting_ThenRounding() {
+
+		assertThat(new DecimalFormat("#.#", new DecimalFormatSymbols(Locale.ENGLISH)).format(d)).isEqualTo("1234567.9");
+
+		assertThat(new DecimalFormat("#", new DecimalFormatSymbols(Locale.ENGLISH)).format(d)).isEqualTo("1234568");
+
+	}
+
+	@Test
+	public void givenGroupingSeparator_WhenFormatting_ThenGroupedOutput() {
+
+		assertThat(new DecimalFormat("#,###.#", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
+				.isEqualTo("1,234,567.9");
+
+		assertThat(new DecimalFormat("#,###", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
+				.isEqualTo("1,234,568");
+
+	}
+
+	@Test
+	public void givenMixedPattern_WhenFormatting_ThenCorrectOutput() {
+
+		assertThat(new DecimalFormat("The # number", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
+				.isEqualTo("The 1234568 number");
+
+		assertThat(new DecimalFormat("The '#' # number", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
+				.isEqualTo("The # 1234568 number");
+
+	}
+
+	@Test
+	public void givenLocales_WhenFormatting_ThenCorrectOutput() {
+
+		assertThat(new DecimalFormat("#,###.##", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
+				.isEqualTo("1,234,567.89");
+
+		assertThat(new DecimalFormat("#,###.##", new DecimalFormatSymbols(Locale.ITALIAN)).format(d))
+				.isEqualTo("1.234.567,89");
+
+		assertThat(new DecimalFormat("#,###.##", DecimalFormatSymbols.getInstance(new Locale("it", "IT"))).format(d))
+				.isEqualTo("1.234.567,89");
+
+	}
+
+	@Test
+	public void givenE_WhenFormatting_ThenScientificNotation() {
+
+		assertThat(new DecimalFormat("00.#######E0", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
+				.isEqualTo("12.3456789E5");
+
+		assertThat(new DecimalFormat("000.000000E0", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
+				.isEqualTo("123.456789E4");
+
+		assertThat(new DecimalFormat("##0.######E0", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
+				.isEqualTo("1.23456789E6");
+
+		assertThat(new DecimalFormat("###.000000E0", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
+				.isEqualTo("1.23456789E6");
+
+	}
+
+	@Test
+	public void givenString_WhenParsing_ThenCorrectOutput() throws ParseException {
+
+		assertThat(new DecimalFormat("", new DecimalFormatSymbols(Locale.ENGLISH)).parse("1234567.89"))
+				.isEqualTo(1234567.89);
+
+		assertThat(new DecimalFormat("", new DecimalFormatSymbols(Locale.ITALIAN)).parse("1.234.567,89"))
+				.isEqualTo(1234567.89);
+
+	}
+
+	@Test
+	public void givenStringAndBigDecimalFlag_WhenParsing_ThenCorrectOutput() throws ParseException {
+
+		NumberFormat nf = new DecimalFormat("", new DecimalFormatSymbols(Locale.ENGLISH));
+		((DecimalFormat) nf).setParseBigDecimal(true);
+		assertThat(nf.parse("1234567.89")).isEqualTo(BigDecimal.valueOf(1234567.89));
+	}
+
+}
@@ -0,0 +1,41 @@
+package com.baeldung.methodoverloadingoverriding.test;
+
+import com.baeldung.methodoverloadingoverriding.util.Multiplier;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.assertj.core.api.Assertions.*;
+
+public class MethodOverloadingUnitTest {
+    
+    private static Multiplier multiplier;
+    
+    @BeforeClass
+    public static void setUpMultiplierInstance() {
+        multiplier = new Multiplier();
+    }
+ 
+    @Test
+    public void givenMultiplierInstance_whenCalledMultiplyWithTwoIntegers_thenOneAssertion() {
+        assertThat(multiplier.multiply(10, 10)).isEqualTo(100);
+    }
+    
+    @Test
+    public void givenMultiplierInstance_whenCalledMultiplyWithTreeIntegers_thenOneAssertion() {
+        assertThat(multiplier.multiply(10, 10, 10)).isEqualTo(1000);
+    }
+    
+    @Test
+    public void givenMultiplierInstance_whenCalledMultiplyWithIntDouble_thenOneAssertion() {
+        assertThat(multiplier.multiply(10, 10.5)).isEqualTo(105.0);
+    }
+    
+    @Test
+    public void givenMultiplierInstance_whenCalledMultiplyWithDoubleDouble_thenOneAssertion() {
+        assertThat(multiplier.multiply(10.5, 10.5)).isEqualTo(110.25);
+    }
+    
+    @Test
+    public void givenMultiplierInstance_whenCalledMultiplyWithIntIntAndMatching_thenNoTypePromotion() {
+        assertThat(multiplier.multiply(10, 10)).isEqualTo(100);
+    }
+}
--- a/Show More
+++ b/Show More