Merge pull request iluwatar#1220 from anuragagarwal561994/java-11

Java 11 (patterns with m)

Author: iluwatar

marker/src/main/java/App.java

@@ -46,17 +46,18 @@ public class App {
    * @param args command line args
    */
   public static void main(String[] args) {
+    final var logger = LoggerFactory.getLogger(App.class);
+    var guard = new Guard();
+    var thief = new Thief();
 
-    final Logger logger = LoggerFactory.getLogger(App.class);
-    Guard guard = new Guard();
-    Thief thief = new Thief();
-
+    //noinspection ConstantConditions
     if (guard instanceof Permission) {
       guard.enter();
     } else {
       logger.info("You have no permission to enter, please leave this area");
     }
 
+    //noinspection ConstantConditions
     if (thief instanceof Permission) {
       thief.steal();
     } else {

marker/src/main/java/Guard.java

@@ -28,11 +28,9 @@
  * Class defining Guard.
  */
 public class Guard implements Permission {
-
   private static final Logger LOGGER = LoggerFactory.getLogger(Guard.class);
 
-  protected static void enter() {
-
+  protected void enter() {
     LOGGER.info("You can enter");
   }
 }

marker/src/main/java/Thief.java

@@ -28,14 +28,13 @@
  * Class defining Thief.
  */
 public class Thief {
-
   private static final Logger LOGGER = LoggerFactory.getLogger(Thief.class);
 
-  protected static void steal() {
+  protected void steal() {
     LOGGER.info("Steal valuable items");
   }
 
-  protected static void doNothing() {
+  protected void doNothing() {
     LOGGER.info("Pretend nothing happened and just leave");
   }
 }

marker/src/test/java/AppTest.java

@@ -30,7 +30,6 @@ public class AppTest {
 
   @Test
   public void test() {
-    String[] args = {};
-    App.main(args);
+    App.main(new String[]{});
   }
 }

marker/src/test/java/GuardTest.java

@@ -33,7 +33,7 @@ public class GuardTest {
 
   @Test
   public void testGuard() {
-    Guard guard = new Guard();
+    var guard = new Guard();
     assertThat(guard, instanceOf(Permission.class));
   }
 }

marker/src/test/java/ThiefTest.java

@@ -21,17 +21,19 @@
  * THE SOFTWARE.
  */
 
-import org.junit.jupiter.api.Test;
+import static org.hamcrest.CoreMatchers.instanceOf;
+import static org.hamcrest.CoreMatchers.not;
+import static org.hamcrest.MatcherAssert.assertThat;
 
-import static org.junit.jupiter.api.Assertions.assertFalse;
+import org.junit.jupiter.api.Test;
 
 /**
  * Thief test
  */
 public class ThiefTest {
   @Test
   public void testThief() {
-    Thief thief = new Thief();
-    assertFalse(thief instanceof Permission);
+    var thief = new Thief();
+    assertThat(thief, not(instanceOf(Permission.class)));
   }
 }

master-worker-pattern/pom.xml

@@ -22,38 +22,39 @@
     THE SOFTWARE.
 
 -->
-<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>
-  <parent>
-    <groupId>com.iluwatar</groupId>
-    <artifactId>java-design-patterns</artifactId>
-    <version>1.23.0-SNAPSHOT</version>
-  </parent>
-  <artifactId>master-worker-pattern</artifactId>
-  <dependencies>
-      <dependency>
-          <groupId>org.junit.jupiter</groupId>
-          <artifactId>junit-jupiter-engine</artifactId>
-          <scope>test</scope>
-      </dependency>
+<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>
+    <parent>
+        <groupId>com.iluwatar</groupId>
+        <artifactId>java-design-patterns</artifactId>
+        <version>1.23.0-SNAPSHOT</version>
+    </parent>
+    <artifactId>master-worker-pattern</artifactId>
+    <dependencies>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
-  <build>
-    <plugins>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-assembly-plugin</artifactId>
-        <executions>
-          <execution>
-            <configuration>
-              <archive>
-                <manifest>
-                  <mainClass>com.iluwatar.masterworker.App</mainClass>
-                </manifest>
-              </archive>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
-    </plugins>
-  </build>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-assembly-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <configuration>
+                            <archive>
+                                <manifest>
+                                    <mainClass>com.iluwatar.masterworker.App</mainClass>
+                                </manifest>
+                            </archive>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
 </project>

master-worker-pattern/src/main/java/com/iluwatar/masterworker/App.java

@@ -34,27 +34,25 @@
 
 /**
  * <p>The <b><em>Master-Worker</em></b> pattern is used when the problem at hand can be solved by
- * dividing into
- * multiple parts which need to go through the same computation and may need to be aggregated to get
- * final result. Parallel processing is performed using a system consisting of a master and some
- * number of workers, where a master divides the work among the workers, gets the result back from
- * them and assimilates all the results to give final result. The only communication is between the
- * master and the worker - none of the workers communicate among one another and the user only
- * communicates with the master to get required job done.</p>
+ * dividing into multiple parts which need to go through the same computation and may need to be
+ * aggregated to get final result. Parallel processing is performed using a system consisting of a
+ * master and some number of workers, where a master divides the work among the workers, gets the
+ * result back from them and assimilates all the results to give final result. The only
+ * communication is between the master and the worker - none of the workers communicate among one
+ * another and the user only communicates with the master to get required job done.</p>
  * <p>In our example, we have generic abstract classes {@link MasterWorker}, {@link Master} and
- * {@link Worker} which
- * have to be extended by the classes which will perform the specific job at hand (in this case
- * finding transpose of matrix, done by {@link ArrayTransposeMasterWorker}, {@link
- * ArrayTransposeMaster} and {@link ArrayTransposeWorker}). The Master class divides the work into
- * parts to be given to the workers, collects the results from the workers and aggregates it when
- * all workers have responded before returning the solution. The Worker class extends the Thread
- * class to enable parallel processing, and does the work once the data has been received from the
- * Master. The MasterWorker contains a reference to the Master class, gets the input from the App
- * and passes it on to the Master. These 3 classes define the system which computes the result. We
- * also have 2 abstract classes {@link Input} and {@link Result}, which contain the input data and
- * result data respectively. The Input class also has an abstract method divideData which defines
- * how the data is to be divided into segments. These classes are extended by {@link ArrayInput} and
- * {@link ArrayResult}.</p>
+ * {@link Worker} which have to be extended by the classes which will perform the specific job at
+ * hand (in this case finding transpose of matrix, done by {@link ArrayTransposeMasterWorker},
+ * {@link ArrayTransposeMaster} and {@link ArrayTransposeWorker}). The Master class divides the work
+ * into parts to be given to the workers, collects the results from the workers and aggregates it
+ * when all workers have responded before returning the solution. The Worker class extends the
+ * Thread class to enable parallel processing, and does the work once the data has been received
+ * from the Master. The MasterWorker contains a reference to the Master class, gets the input from
+ * the App and passes it on to the Master. These 3 classes define the system which computes the
+ * result. We also have 2 abstract classes {@link Input} and {@link Result}, which contain the input
+ * data and result data respectively. The Input class also has an abstract method divideData which
+ * defines how the data is to be divided into segments. These classes are extended by {@link
+ * ArrayInput} and {@link ArrayResult}.</p>
  */
 
 public class App {
@@ -68,12 +66,12 @@ public class App {
    */
 
   public static void main(String[] args) {
-    ArrayTransposeMasterWorker mw = new ArrayTransposeMasterWorker();
-    int rows = 10;
-    int columns = 20;
-    int[][] inputMatrix = ArrayUtilityMethods.createRandomIntMatrix(rows, columns);
-    ArrayInput input = new ArrayInput(inputMatrix);
-    ArrayResult result = (ArrayResult) mw.getResult(input);
+    var mw = new ArrayTransposeMasterWorker();
+    var rows = 10;
+    var columns = 20;
+    var inputMatrix = ArrayUtilityMethods.createRandomIntMatrix(rows, columns);
+    var input = new ArrayInput(inputMatrix);
+    var result = (ArrayResult) mw.getResult(input);
     if (result != null) {
       ArrayUtilityMethods.printMatrix(inputMatrix);
       ArrayUtilityMethods.printMatrix(result.data);

master-worker-pattern/src/main/java/com/iluwatar/masterworker/ArrayInput.java

@@ -25,6 +25,7 @@
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.List;
 
 /**
  * Class ArrayInput extends abstract class {@link Input} and contains data of type int[][].
@@ -37,12 +38,12 @@ public ArrayInput(int[][] data) {
   }
 
   static int[] makeDivisions(int[][] data, int num) {
-    int initialDivision = data.length / num; //equally dividing
-    int[] divisions = new int[num];
+    var initialDivision = data.length / num; //equally dividing
+    var divisions = new int[num];
     Arrays.fill(divisions, initialDivision);
     if (initialDivision * num != data.length) {
-      int extra = data.length - initialDivision * num;
-      int l = 0;
+      var extra = data.length - initialDivision * num;
+      var l = 0;
       //equally dividing extra among all parts
       while (extra > 0) {
         divisions[l] = divisions[l] + 1;
@@ -58,22 +59,20 @@ static int[] makeDivisions(int[][] data, int num) {
   }
 
   @Override
-  public ArrayList<Input> divideData(int num) {
+  public List<Input<int[][]>> divideData(int num) {
     if (this.data == null) {
       return null;
     } else {
-      int[] divisions = makeDivisions(this.data, num);
-      ArrayList<Input> result = new ArrayList<Input>(num);
-      int rowsDone = 0; //number of rows divided so far
-      for (int i = 0; i < num; i++) {
-        int rows = divisions[i];
+      var divisions = makeDivisions(this.data, num);
+      var result = new ArrayList<Input<int[][]>>(num);
+      var rowsDone = 0; //number of rows divided so far
+      for (var i = 0; i < num; i++) {
+        var rows = divisions[i];
         if (rows != 0) {
-          int[][] divided = new int[rows][this.data[0].length];
-          for (int j = 0; j < rows; j++) {
-            divided[j] = this.data[rowsDone + j];
-          }
+          var divided = new int[rows][this.data[0].length];
+          System.arraycopy(this.data, rowsDone, divided, 0, rows);
           rowsDone += rows;
-          ArrayInput dividedInput = new ArrayInput(divided);
+          var dividedInput = new ArrayInput(divided);
           result.add(dividedInput);
         } else {
           break; //rest of divisions will also be 0

master-worker-pattern/src/main/java/com/iluwatar/masterworker/ArrayUtilityMethods.java

@@ -47,8 +47,8 @@ public static boolean arraysSame(int[] a1, int[] a2) {
     if (a1.length != a2.length) {
       return false;
     } else {
-      boolean answer = false;
-      for (int i = 0; i < a1.length; i++) {
+      var answer = false;
+      for (var i = 0; i < a1.length; i++) {
         if (a1[i] == a2[i]) {
           answer = true;
         } else {
@@ -69,8 +69,8 @@ public static boolean matricesSame(int[][] m1, int[][] m2) {
     if (m1.length != m2.length) {
       return false;
     } else {
-      boolean answer = false;
-      for (int i = 0; i < m1.length; i++) {
+      var answer = false;
+      for (var i = 0; i < m1.length; i++) {
         if (arraysSame(m1[i], m2[i])) {
           answer = true;
         } else {
@@ -88,9 +88,9 @@ public static boolean matricesSame(int[][] m1, int[][] m2) {
    * @return it (int[][]).
    */
   public static int[][] createRandomIntMatrix(int rows, int columns) {
-    int[][] matrix = new int[rows][columns];
-    for (int i = 0; i < rows; i++) {
-      for (int j = 0; j < columns; j++) {
+    var matrix = new int[rows][columns];
+    for (var i = 0; i < rows; i++) {
+      for (var j = 0; j < columns; j++) {
         //filling cells in matrix
         matrix[i][j] = RANDOM.nextInt(10);
       }
@@ -104,9 +104,9 @@ public static int[][] createRandomIntMatrix(int rows, int columns) {
 
   public static void printMatrix(int[][] matrix) {
     //prints out int[][]
-    for (int i = 0; i < matrix.length; i++) {
-      for (int j = 0; j < matrix[0].length; j++) {
-        LOGGER.info(matrix[i][j] + " ");
+    for (var ints : matrix) {
+      for (var j = 0; j < matrix[0].length; j++) {
+        LOGGER.info(ints[j] + " ");
       }
       LOGGER.info("");
     }

master-worker-pattern/src/main/java/com/iluwatar/masterworker/Input.java

@@ -23,7 +23,7 @@
 
 package com.iluwatar.masterworker;
 
-import java.util.ArrayList;
+import java.util.List;
 
 /**
  * The abstract Input class, having 1 public field which contains input data, and abstract method
@@ -40,5 +40,5 @@ public Input(T data) {
     this.data = data;
   }
 
-  public abstract ArrayList<Input> divideData(int num);
+  public abstract List<Input<T>> divideData(int num);
 }

master-worker-pattern/src/main/java/com/iluwatar/masterworker/system/MasterWorker.java

@@ -40,7 +40,7 @@ public MasterWorker(int numOfWorkers) {
 
   abstract Master setMaster(int numOfWorkers);
 
-  public Result getResult(Input input) {
+  public Result<?> getResult(Input<?> input) {
     this.master.doWork(input);
     return this.master.getFinalResult();
   }