Merge branch 'master' of https://github.com/eugenp/tutorials

cas/cas-secured-app/src/main/java/com/baeldung/cassecuredapp/controllers/AuthController.java

@@ -1,6 +1,7 @@
 package com.baeldung.cassecuredapp.controllers;
 
-import org.apache.log4j.Logger;
+import org.apache.logging.log4j.Logger;
+import org.apache.logging.log4j.LogManager;
 import org.springframework.security.core.Authentication;
 import org.springframework.security.core.context.SecurityContextHolder;
 import org.springframework.security.web.authentication.logout.CookieClearingLogoutHandler;
@@ -15,7 +16,7 @@ import javax.servlet.http.HttpServletResponse;
 @Controller
 public class AuthController {
 
-    private Logger logger = Logger.getLogger(AuthController.class);
+    private Logger logger = LogManager.getLogger(AuthController.class);
 
     @GetMapping("/logout")
     public String logout(

core-java-8/src/test/java/com/baeldung/counter/CounterStatistics.java

@@ -0,0 +1,45 @@
+package com.baeldung.counter;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Mode;
+
+import com.baeldung.counter.CounterUtil.MutableInteger;
+
+@Fork(value = 1, warmups = 3)
+@BenchmarkMode(Mode.All)
+public class CounterStatistics {
+
+    private static final Map<String, Integer> counterMap = new HashMap<>();
+    private static final Map<String, MutableInteger> counterWithMutableIntMap = new HashMap<>();
+    private static final Map<String, int[]> counterWithIntArrayMap = new HashMap<>();
+    private static final Map<String, Long> counterWithLongWrapperMap = new HashMap<>();
+
+    @Benchmark
+    public void wrapperAsCounter() {
+        CounterUtil.counterWithWrapperObject(counterMap);
+    }
+
+    @Benchmark
+    public void lambdaExpressionWithWrapper() {
+        CounterUtil.counterWithLambdaAndWrapper(counterWithLongWrapperMap);
+    }
+
+    @Benchmark
+    public void mutableIntegerAsCounter() {
+        CounterUtil.counterWithMutableInteger(counterWithMutableIntMap);
+    }
+
+    @Benchmark
+    public void primitiveArrayAsCounter() {
+        CounterUtil.counterWithPrimitiveArray(counterWithIntArrayMap);
+    }
+
+    public static void main(String[] args) throws Exception {
+        org.openjdk.jmh.Main.main(args);
+    }
+}

core-java-8/src/test/java/com/baeldung/counter/CounterTest.java

@@ -0,0 +1,53 @@
+package com.baeldung.counter;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+import com.baeldung.counter.CounterUtil.MutableInteger;
+
+public class CounterTest {
+
+    @Test
+    public void whenMapWithWrapperAsCounter_runsSuccessfully() {
+        Map<String, Integer> counterMap = new HashMap<>();
+        CounterUtil.counterWithWrapperObject(counterMap);
+
+        assertEquals(3, counterMap.get("China")
+            .intValue());
+        assertEquals(2, counterMap.get("India")
+            .intValue());
+    }
+
+    @Test
+    public void whenMapWithLambdaAndWrapperCounter_runsSuccessfully() {
+        Map<String, Long> counterMap = new HashMap<>();
+        CounterUtil.counterWithLambdaAndWrapper(counterMap);
+
+        assertEquals(3l, counterMap.get("China")
+            .longValue());
+        assertEquals(2l, counterMap.get("India")
+            .longValue());
+    }
+
+    @Test
+    public void whenMapWithMutableIntegerCounter_runsSuccessfully() {
+        Map<String, MutableInteger> counterMap = new HashMap<>();
+        CounterUtil.counterWithMutableInteger(counterMap);
+        assertEquals(3, counterMap.get("China")
+            .getCount());
+        assertEquals(2, counterMap.get("India")
+            .getCount());
+    }
+
+    @Test
+    public void whenMapWithPrimitiveArray_runsSuccessfully() {
+        Map<String, int[]> counterMap = new HashMap<>();
+        CounterUtil.counterWithPrimitiveArray(counterMap);
+        assertEquals(3, counterMap.get("China")[0]);
+        assertEquals(2, counterMap.get("India")[0]);
+    }
+}

core-java-8/src/test/java/com/baeldung/counter/CounterUtil.java

@@ -0,0 +1,61 @@
+package com.baeldung.counter;
+
+import java.util.Map;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class CounterUtil {
+
+    private final static String[] COUNTRY_NAMES = { "China", "Australia", "India", "USA", "USSR", "UK", "China", "France", "Poland", "Austria", "India", "USA", "Egypt", "China" };
+
+    public static void counterWithWrapperObject(Map<String, Integer> counterMap) {
+        for (String country : COUNTRY_NAMES) {
+            counterMap.compute(country, (k, v) -> v == null ? 1 : v + 1);
+        }
+    }
+
+    public static void counterWithLambdaAndWrapper(Map<String, Long> counterMap) {
+        counterMap.putAll(Stream.of(COUNTRY_NAMES)
+            .parallel()
+            .collect(Collectors.groupingBy(k -> k, Collectors.counting())));
+    }
+
+    public static class MutableInteger {
+        int count;
+
+        public MutableInteger(int count) {
+            this.count = count;
+        }
+
+        public void increment() {
+            this.count++;
+        }
+
+        public int getCount() {
+            return this.count;
+        }
+    }
+
+    public static void counterWithMutableInteger(Map<String, MutableInteger> counterMap) {
+        for (String country : COUNTRY_NAMES) {
+            MutableInteger oldValue = counterMap.get(country);
+            if (oldValue != null) {
+                oldValue.increment();
+            } else {
+                counterMap.put(country, new MutableInteger(1));
+            }
+        }
+    }
+
+    public static void counterWithPrimitiveArray(Map<String, int[]> counterMap) {
+        for (String country : COUNTRY_NAMES) {
+            int[] oldCounter = counterMap.get(country);
+            if (oldCounter != null) {
+                oldCounter[0] += 1;
+            } else {
+                counterMap.put(country, new int[] { 1 });
+            }
+        }
+    }
+
+}

core-java-9/compile-httpclient.bat

@@ -0,0 +1,3 @@
+javac --module-path mods -d mods/com.baeldung.httpclient^
+ src/modules/com.baeldung.httpclient/module-info.java^
+ src/modules/com.baeldung.httpclient/com/baeldung/httpclient/HttpClientExample.java

core-java-9/run-httpclient.bat

@@ -0,0 +1 @@
+java --module-path mods -m com.baeldung.httpclient/com.baeldung.httpclient.HttpClientExample

core-java-9/src/modules/com.baeldung.httpclient/com/baeldung/httpclient/HttpClientExample.java

@@ -0,0 +1,84 @@
+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package com.baeldung.httpclient;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.stream.Collectors;
+import jdk.incubator.http.HttpClient;
+import jdk.incubator.http.HttpRequest;
+import jdk.incubator.http.HttpRequest.BodyProcessor;
+import jdk.incubator.http.HttpResponse;
+import jdk.incubator.http.HttpResponse.BodyHandler;
+
+/**
+ *
+ * @author pkaria
+ */
+public class HttpClientExample {
+    
+    public static void main(String[] args) throws Exception {
+        httpGetRequest();
+        httpPostRequest();
+        asynchronousRequest();
+        asynchronousMultipleRequests();
+    }
+
+    public static void httpGetRequest() throws URISyntaxException, IOException, InterruptedException {
+        HttpClient client = HttpClient.newHttpClient();
+        URI httpURI = new URI("http://jsonplaceholder.typicode.com/posts/1");
+        HttpRequest request = HttpRequest.newBuilder(httpURI).GET()
+          .headers("Accept-Enconding", "gzip, deflate").build();
+        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandler.asString());
+        String responseBody = response.body();
+        int responseStatusCode = response.statusCode();
+        System.out.println(responseBody);
+    }
+
+    public static void httpPostRequest() throws URISyntaxException, IOException, InterruptedException {
+        HttpClient client = HttpClient
+                .newBuilder()
+                .build();
+        HttpRequest request = HttpRequest
+                .newBuilder(new URI("http://jsonplaceholder.typicode.com/posts"))
+                .POST(BodyProcessor.fromString("Sample Post Request"))
+                .build();
+        HttpResponse<String> response
+                = client.send(request, HttpResponse.BodyHandler.asString());
+        String responseBody = response.body();
+        System.out.println(responseBody);
+    }
+
+    public static void asynchronousRequest() throws URISyntaxException {
+        HttpClient client = HttpClient.newHttpClient();
+        URI httpURI = new URI("http://jsonplaceholder.typicode.com/posts/1");
+        HttpRequest request = HttpRequest.newBuilder(httpURI).GET().build();
+        CompletableFuture<HttpResponse<String>> futureResponse = client.sendAsync(request,
+                HttpResponse.BodyHandler.asString());
+    }
+
+    public static void asynchronousMultipleRequests() throws URISyntaxException {
+        List<URI> targets = Arrays.asList(new URI("http://jsonplaceholder.typicode.com/posts/1"), new URI("http://jsonplaceholder.typicode.com/posts/2"));
+        HttpClient client = HttpClient.newHttpClient();
+        List<CompletableFuture<File>> futures = targets
+                .stream()
+                .map(target -> client
+                .sendAsync(
+                        HttpRequest.newBuilder(target)
+                                .GET()
+                                .build(),
+                        BodyHandler.asFile(Paths.get("base", target.getPath())))
+                .thenApply(response -> response.body())
+                .thenApply(path -> path.toFile()))
+                .collect(Collectors.toList());
+    }
+}

core-java-9/src/modules/com.baeldung.httpclient/module-info.java

@@ -0,0 +1,3 @@
+module com.baeldung.httpclient {   
+	requires jdk.incubator.httpclient;
+}

core-java-concurrency/src/test/java/com/baeldung/concurrent/executorservice/WaitingForThreadsToFinishTest.java

@@ -9,7 +9,6 @@ import java.util.List;
 import java.util.concurrent.*;
 
 import static junit.framework.TestCase.assertTrue;
-import static org.junit.Assert.fail;
 
 public class WaitingForThreadsToFinishTest {
 
@@ -40,16 +39,13 @@ public class WaitingForThreadsToFinishTest {
             CountDownLatch latch = new CountDownLatch(2);
             
             for (int i = 0; i < 2; i++) {
-                WORKER_THREAD_POOL.submit(new Runnable() {                
-                    @Override
-                    public void run() {
-                        try {
-                            Thread.sleep(1000);
-                            latch.countDown();
-                        } catch (InterruptedException e) {
-                            e.printStackTrace();
-                            Thread.currentThread().interrupt();
-                        }
+                WORKER_THREAD_POOL.submit(() -> {
+                    try {
+                        Thread.sleep(1000);
+                        latch.countDown();
+                    } catch (InterruptedException e) {
+                        e.printStackTrace();
+                        Thread.currentThread().interrupt();
                     }
                 });
             }
@@ -83,13 +79,9 @@ public class WaitingForThreadsToFinishTest {
             awaitTerminationAfterShutdown(WORKER_THREAD_POOL);
 
             try {
-                WORKER_THREAD_POOL.submit(new Callable<String>() {
-                    @Override
-                    public String call() throws Exception {
-                        fail("This thread should have been rejected !");
-                        Thread.sleep(1000000);
-                        return null;
-                    }
+                WORKER_THREAD_POOL.submit((Callable<String>) () -> {
+                    Thread.sleep(1000000);
+                    return null;
                 });
             } catch (RejectedExecutionException ex) {
                 //

core-java/README.md

@@ -120,4 +120,5 @@
 - [Guide to Java String Pool](http://www.baeldung.com/java-string-pool)
 - [Copy a File with Java](http://www.baeldung.com/java-copy-file)
 - [Introduction to Creational Design Patterns](http://www.baeldung.com/creational-design-patterns)
+- [Quick Example - Comparator vs Comparable in Java](http://www.baeldung.com/java-comparator-comparable)
 

core-java/customers.xml

@@ -0,0 +1,95 @@
+<?xml version="1.0"?>
+<webRowSet xmlns="http://java.sun.com/xml/ns/jdbc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+xsi:schemaLocation="http://java.sun.com/xml/ns/jdbc http://java.sun.com/xml/ns/jdbc/webrowset.xsd">
+  <properties>
+    <command>SELECT * FROM customers</command>
+    <concurrency>1008</concurrency>
+    <datasource><null/></datasource>
+    <escape-processing>true</escape-processing>
+    <fetch-direction>1000</fetch-direction>
+    <fetch-size>0</fetch-size>
+    <isolation-level>2</isolation-level>
+    <key-columns>
+    </key-columns>
+    <map>
+    </map>
+    <max-field-size>0</max-field-size>
+    <max-rows>0</max-rows>
+    <query-timeout>0</query-timeout>
+    <read-only>true</read-only>
+    <rowset-type>ResultSet.TYPE_SCROLL_INSENSITIVE</rowset-type>
+    <show-deleted>false</show-deleted>
+    <table-name>customers</table-name>
+    <url>jdbc:h2:mem:testdb</url>
+    <sync-provider>
+      <sync-provider-name>com.sun.rowset.providers.RIOptimisticProvider</sync-provider-name>
+      <sync-provider-vendor>Oracle Corporation</sync-provider-vendor>
+      <sync-provider-version>1.0</sync-provider-version>
+      <sync-provider-grade>2</sync-provider-grade>
+      <data-source-lock>1</data-source-lock>
+    </sync-provider>
+  </properties>
+  <metadata>
+    <column-count>2</column-count>
+    <column-definition>
+      <column-index>1</column-index>
+      <auto-increment>false</auto-increment>
+      <case-sensitive>true</case-sensitive>
+      <currency>false</currency>
+      <nullable>0</nullable>
+      <signed>true</signed>
+      <searchable>true</searchable>
+      <column-display-size>11</column-display-size>
+      <column-label>ID</column-label>
+      <column-name>ID</column-name>
+      <schema-name>PUBLIC</schema-name>
+      <column-precision>10</column-precision>
+      <column-scale>0</column-scale>
+      <table-name>CUSTOMERS</table-name>
+      <catalog-name>TESTDB</catalog-name>
+      <column-type>4</column-type>
+      <column-type-name>INTEGER</column-type-name>
+    </column-definition>
+    <column-definition>
+      <column-index>2</column-index>
+      <auto-increment>false</auto-increment>
+      <case-sensitive>true</case-sensitive>
+      <currency>false</currency>
+      <nullable>0</nullable>
+      <signed>true</signed>
+      <searchable>true</searchable>
+      <column-display-size>50</column-display-size>
+      <column-label>NAME</column-label>
+      <column-name>NAME</column-name>
+      <schema-name>PUBLIC</schema-name>
+      <column-precision>50</column-precision>
+      <column-scale>0</column-scale>
+      <table-name>CUSTOMERS</table-name>
+      <catalog-name>TESTDB</catalog-name>
+      <column-type>12</column-type>
+      <column-type-name>VARCHAR</column-type-name>
+    </column-definition>
+  </metadata>
+  <data>
+    <currentRow>
+      <columnValue>1</columnValue>
+      <columnValue>Customer1</columnValue>
+    </currentRow>
+    <currentRow>
+      <columnValue>2</columnValue>
+      <columnValue>Customer2</columnValue>
+    </currentRow>
+    <currentRow>
+      <columnValue>3</columnValue>
+      <columnValue>Customer3</columnValue>
+    </currentRow>
+    <currentRow>
+      <columnValue>4</columnValue>
+      <columnValue>Customer4</columnValue>
+    </currentRow>
+    <currentRow>
+      <columnValue>5</columnValue>
+      <columnValue>Customer5</columnValue>
+    </currentRow>
+  </data>
+</webRowSet>

core-java/src/main/java/com/baeldung/jdbcrowset/DatabaseConfiguration.java

@@ -0,0 +1,51 @@
+package com.baeldung.jdbcrowset;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+import javax.sql.rowset.JdbcRowSet;
+import javax.sql.rowset.RowSetFactory;
+import javax.sql.rowset.RowSetProvider;
+
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@EnableAutoConfiguration
+public class DatabaseConfiguration {
+ 
+    
+    public static Connection geth2Connection() throws Exception {
+        Class.forName("org.h2.Driver");
+        System.out.println("Driver Loaded.");
+        String url = "jdbc:h2:mem:testdb";
+        return DriverManager.getConnection(url, "sa", "");
+      }
+    
+    public static void initDatabase(Statement stmt) throws SQLException{
+        int iter = 1;
+        while(iter<=5){
+            String customer = "Customer"+iter;
+            String sql ="INSERT INTO customers(id, name) VALUES ("+iter+ ",'"+customer+"');";
+            System.out.println("here is sql statmeent for execution: " + sql);
+            stmt.executeUpdate(sql);
+            iter++;
+        }
+        
+        int iterb = 1;
+        while(iterb<=5){
+            String associate = "Associate"+iter;
+            String sql = "INSERT INTO associates(id, name) VALUES("+iterb+",'"+associate+"');";
+            System.out.println("here is sql statement for associate:"+ sql);
+            stmt.executeUpdate(sql);
+            iterb++;
+        }
+        
+        
+    }
+    
+    
+
+}

core-java/src/main/java/com/baeldung/jdbcrowset/ExampleListener.java

@@ -0,0 +1,24 @@
+package com.baeldung.jdbcrowset;
+
+import javax.sql.RowSetEvent;
+import javax.sql.RowSetListener;
+
+public class ExampleListener implements RowSetListener {
+    
+
+    public void cursorMoved(RowSetEvent event) {
+      System.out.println("ExampleListener alerted of cursorMoved event");
+      System.out.println(event.toString());
+    }
+
+    public void rowChanged(RowSetEvent event) {
+      System.out.println("ExampleListener alerted of rowChanged event");
+      System.out.println(event.toString());
+    }
+
+    public void rowSetChanged(RowSetEvent event) {
+      System.out.println("ExampleListener alerted of rowSetChanged event");
+      System.out.println(event.toString());
+    }
+
+}

core-java/src/main/java/com/baeldung/jdbcrowset/FilterExample.java

@@ -0,0 +1,46 @@
+package com.baeldung.jdbcrowset;
+
+import java.sql.SQLException;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import javax.sql.RowSet;
+import javax.sql.rowset.Predicate;
+
+public class FilterExample implements Predicate {
+    
+    private Pattern pattern;
+    
+    public FilterExample(String regexQuery) {
+        if (regexQuery != null && !regexQuery.isEmpty()) {
+            pattern = Pattern.compile(regexQuery);
+        }
+    }
+ 
+    public boolean evaluate(RowSet rs) {
+        try {
+            if (!rs.isAfterLast()) {
+                String name = rs.getString("name");
+                System.out.println(String.format(
+                        "Searching for pattern '%s' in %s", pattern.toString(),
+                        name));
+                Matcher matcher = pattern.matcher(name);
+                return matcher.matches();
+            } else
+                return false;
+        } catch (Exception e) {
+            e.printStackTrace();
+            return false;
+        }
+    }
+ 
+    public boolean evaluate(Object value, int column) throws SQLException {
+        throw new UnsupportedOperationException("This operation is unsupported.");
+    }
+ 
+    public boolean evaluate(Object value, String columnName)
+            throws SQLException {
+        throw new UnsupportedOperationException("This operation is unsupported.");
+    }
+
+}

core-java/src/main/java/com/baeldung/jdbcrowset/JdbcRowsetApplication.java

@@ -0,0 +1,139 @@
+package com.baeldung.jdbcrowset;
+
+import java.io.FileOutputStream;
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.ResultSetMetaData;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+import com.sun.rowset.*;
+
+import javax.sql.rowset.CachedRowSet;
+import javax.sql.rowset.FilteredRowSet;
+import javax.sql.rowset.JdbcRowSet;
+import javax.sql.rowset.JoinRowSet;
+import javax.sql.rowset.RowSetFactory;
+import javax.sql.rowset.RowSetProvider;
+import javax.sql.rowset.WebRowSet;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class JdbcRowsetApplication {
+
+    public static void main(String[] args) throws Exception {
+        SpringApplication.run(JdbcRowsetApplication.class, args);
+        Statement stmt = null;
+        try {
+            Connection conn = DatabaseConfiguration.geth2Connection();
+
+            String drop = "DROP TABLE IF EXISTS customers, associates;";
+            String schema = "CREATE TABLE customers (id INT NOT NULL, name VARCHAR(50) NOT NULL, PRIMARY KEY (id)); ";
+            String schemapartb = "CREATE TABLE associates (id INT NOT NULL, name VARCHAR(50) NOT NULL, PRIMARY KEY (id));";
+
+            stmt = conn.createStatement();
+            stmt.executeUpdate(drop);
+            stmt.executeUpdate(schema);
+            stmt.executeUpdate(schemapartb);
+            // insert data
+            DatabaseConfiguration.initDatabase(stmt);
+            // JdbcRowSet Example
+            String sql = "SELECT * FROM customers";
+            JdbcRowSet jdbcRS;
+            jdbcRS = new JdbcRowSetImpl(conn);
+            jdbcRS.setType(ResultSet.TYPE_SCROLL_INSENSITIVE);
+            jdbcRS.setCommand(sql);
+            jdbcRS.execute();
+            jdbcRS.addRowSetListener(new ExampleListener());
+
+            while (jdbcRS.next()) {
+                // each call to next, generates a cursorMoved event
+                System.out.println("id=" + jdbcRS.getString(1));
+                System.out.println("name=" + jdbcRS.getString(2));
+            }
+
+            // CachedRowSet Example
+            String username = "sa";
+            String password = "";
+            String url = "jdbc:h2:mem:testdb";
+            CachedRowSet crs = new CachedRowSetImpl();
+            crs.setUsername(username);
+            crs.setPassword(password);
+            crs.setUrl(url);
+            crs.setCommand(sql);
+            crs.execute();
+            crs.addRowSetListener(new ExampleListener());
+            while (crs.next()) {
+                if (crs.getInt("id") == 1) {
+                    System.out.println("CRS found customer1 and will remove the record.");
+                    crs.deleteRow();
+                    break;
+                }
+            }
+
+            // WebRowSet example
+            WebRowSet wrs = new WebRowSetImpl();
+            wrs.setUsername(username);
+            wrs.setPassword(password);
+            wrs.setUrl(url);
+            wrs.setCommand(sql);
+            wrs.execute();
+            FileOutputStream ostream = new FileOutputStream("customers.xml");
+            wrs.writeXml(ostream);
+
+            // JoinRowSet example
+            CachedRowSetImpl customers = new CachedRowSetImpl();
+            customers.setUsername(username);
+            customers.setPassword(password);
+            customers.setUrl(url);
+            customers.setCommand(sql);
+            customers.execute();
+
+            CachedRowSetImpl associates = new CachedRowSetImpl();
+            associates.setUsername(username);
+            associates.setPassword(password);
+            associates.setUrl(url);
+            String associatesSQL = "SELECT * FROM associates";
+            associates.setCommand(associatesSQL);
+            associates.execute();
+
+            JoinRowSet jrs = new JoinRowSetImpl();
+            final String ID = "id";
+            final String NAME = "name";
+            jrs.addRowSet(customers, ID);
+            jrs.addRowSet(associates, ID);
+            jrs.last();
+            System.out.println("Total rows: " + jrs.getRow());
+            jrs.beforeFirst();
+            while (jrs.next()) {
+
+                String string1 = jrs.getString(ID);
+                String string2 = jrs.getString(NAME);
+                System.out.println("ID: " + string1 + ", NAME: " + string2);
+            }
+
+            // FilteredRowSet example
+            RowSetFactory rsf = RowSetProvider.newFactory();
+            FilteredRowSet frs = rsf.createFilteredRowSet();
+            frs.setCommand("select * from customers");
+            frs.execute(conn);
+            frs.setFilter(new FilterExample("^[A-C].*"));
+
+            ResultSetMetaData rsmd = frs.getMetaData();
+            int columncount = rsmd.getColumnCount();
+            while (frs.next()) {
+                for (int i = 1; i <= columncount; i++) {
+                    System.out.println(rsmd.getColumnLabel(i) + " = " + frs.getObject(i) + " ");
+                }
+            }
+
+        } catch (SQLException e) {
+            // TODO Auto-generated catch block
+            e.printStackTrace();
+        }
+
+    }
+
+}

core-java/src/main/java/com/baeldung/nestedclass/Enclosing.java

@@ -1,11 +0,0 @@
-package com.baeldung.nestedclass;
-
-public class Enclosing {
-
-    public static class Nested {
-
-        public void test() {
-            System.out.println("Calling test...");
-        }
-    }
-}

core-java/src/main/java/com/baeldung/nestedclass/Outer.java

@@ -1,11 +0,0 @@
-package com.baeldung.nestedclass;
-
-public class Outer {
-
-    public class Inner {
-
-        public void test() {
-            System.out.println("Calling test...");
-        }
-    }
-}

core-java/src/main/java/com/baeldung/nestedclass/SimpleAbstractClass.java

@@ -1,5 +0,0 @@
-package com.baeldung.nestedclass;
-
-abstract class SimpleAbstractClass {
-    abstract void run();
-}

core-java/src/main/resources/countries.properties

@@ -1,3 +1,3 @@
-UK
-US
-Germany
+UK
+US
+Germany

core-java/src/test/java/com/baeldung/array/SearchArrayTest.java

@@ -0,0 +1,116 @@
+package com.baeldung.array;
+
+import org.junit.Test;
+
+import java.util.*;
+
+public class SearchArrayTest {
+
+
+    @Test
+    public void searchArrayAllocNewCollections() {
+
+        int count = 1000;
+
+        String[] strings = seedArray(count);
+
+        long startTime = System.nanoTime();
+        for (int i = 0; i < count; i++) {
+            searchList(strings, "W");
+        }
+        long duration = System.nanoTime() - startTime;
+        System.out.println("SearchList:  " + duration / 10000);
+
+        startTime = System.nanoTime();
+        for (int i = 0; i < count; i++) {
+            searchSet(strings,"S");
+        }
+        duration = System.nanoTime() - startTime;
+        System.out.println("SearchSet:  " + duration / 10000);
+
+        startTime = System.nanoTime();
+        for (int i = 0; i < count; i++) {
+            searchLoop(strings, "T");
+        }
+        duration = System.nanoTime() - startTime;
+        System.out.println("SearchLoop:  " + duration / 10000);
+    }
+
+    @Test
+    public void searchArrayReuseCollections() {
+
+        int count = 10000;
+        String[] strings = seedArray(count);
+
+        List<String> asList = Arrays.asList(strings);
+        Set<String> asSet = new HashSet<>(Arrays.asList(strings));
+
+        long startTime = System.nanoTime();
+        for (int i = 0; i < count; i++) {
+            asList.contains("W");
+        }
+        long duration = System.nanoTime() - startTime;
+        System.out.println("List:  " + duration / 10000);
+
+        startTime = System.nanoTime();
+        for (int i = 0; i < count; i++) {
+            asSet.contains("S");
+        }
+        duration = System.nanoTime() - startTime;
+        System.out.println("Set:  " + duration / 10000);
+
+        startTime = System.nanoTime();
+        for (int i = 0; i < count; i++) {
+            searchLoop(strings, "T");
+        }
+        duration = System.nanoTime() - startTime;
+        System.out.println("Loop:  " + duration / 10000);
+
+    }
+
+
+    @Test
+    public void searchArrayBinarySearch() {
+
+        int count = 10000;
+        String[] strings = seedArray(count);
+        Arrays.sort(strings);
+
+        long startTime = System.nanoTime();
+        for (int i = 0; i < count; i++) {
+            Arrays.binarySearch(strings, "A");
+        }
+        long duration = System.nanoTime() - startTime;
+        System.out.println("Binary search:  " + duration / 10000);
+
+    }
+
+    private boolean searchList(String[] strings, String searchString) {
+      return Arrays.asList(strings).contains(searchString);
+  }
+
+    private boolean searchSet(String[] strings, String searchString) {
+        Set<String> set = new HashSet<>(Arrays.asList(strings));
+        return set.contains(searchString);
+    }
+
+    private boolean searchLoop(String[] strings, String searchString) {
+        for (String s : strings) {
+            if (s.equals(searchString))
+            return true;
+        }
+        return false;
+    }
+
+    private String[] seedArray(int length) {
+
+        String[] strings = new String[length];
+        Random random = new Random();
+        for (int i = 0; i < length; i++)
+        {
+            strings[i] = String.valueOf(random.nextInt());
+        }
+        return strings;
+    }
+
+}

core-java/src/test/java/com/baeldung/collection/WhenUsingHashSet.java

@@ -0,0 +1,93 @@
+package com.baeldung.collection;
+
+import java.util.ConcurrentModificationException;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Set;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class WhenUsingHashSet {
+
+    @Test
+    public void whenAddingElement_shouldAddElement() {
+        Set<String> hashset = new HashSet<>();
+        Assert.assertTrue(hashset.add("String Added"));
+    }
+
+    @Test
+    public void whenCheckingForElement_shouldSearchForElement() {
+        Set<String> hashsetContains = new HashSet<>();
+        hashsetContains.add("String Added");
+        Assert.assertTrue(hashsetContains.contains("String Added"));
+    }
+
+    @Test
+    public void whenCheckingTheSizeOfHashSet_shouldReturnThesize() {
+        Set<String> hashSetSize = new HashSet<>();
+        hashSetSize.add("String Added");
+        Assert.assertEquals(1, hashSetSize.size());
+    }
+
+    @Test
+    public void whenCheckingForEmptyHashSet_shouldCheckForEmpty() {
+        Set<String> emptyHashSet = new HashSet<>();
+        Assert.assertTrue(emptyHashSet.isEmpty());
+    }
+
+    @Test
+    public void whenRemovingElement_shouldRemoveElement() {
+        Set<String> removeFromHashSet = new HashSet<>();
+        removeFromHashSet.add("String Added");
+        Assert.assertTrue(removeFromHashSet.remove("String Added"));
+    }
+
+    @Test
+    public void whenClearingHashSet_shouldClearHashSet() {
+        Set<String> clearHashSet = new HashSet<>();
+        clearHashSet.add("String Added");
+        clearHashSet.clear();
+        Assert.assertTrue(clearHashSet.isEmpty());
+    }
+
+    @Test
+    public void whenIteratingHashSet_shouldIterateHashSet() {
+        Set<String> hashset = new HashSet<>();
+        hashset.add("First");
+        hashset.add("Second");
+        hashset.add("Third");
+        Iterator<String> itr = hashset.iterator();
+        while (itr.hasNext()) {
+            System.out.println(itr.next());
+        }
+    }
+
+    @Test(expected = ConcurrentModificationException.class)
+    public void whenModifyingHashSetWhileIterating_shouldThrowException() {
+        Set<String> hashset = new HashSet<>();
+        hashset.add("First");
+        hashset.add("Second");
+        hashset.add("Third");
+        Iterator<String> itr = hashset.iterator();
+        while (itr.hasNext()) {
+            itr.next();
+            hashset.remove("Second");
+        }
+    }
+
+    @Test
+    public void whenRemovingElementUsingIterator_shouldRemoveElement() {
+        Set<String> hashset = new HashSet<>();
+        hashset.add("First");
+        hashset.add("Second");
+        hashset.add("Third");
+        Iterator<String> itr = hashset.iterator();
+        while (itr.hasNext()) {
+            String element = itr.next();
+            if (element.equals("Second"))
+                itr.remove();
+        }
+        Assert.assertEquals(2, hashset.size());
+    }
+}

core-java/src/test/java/com/baeldung/jdbcrowset/JdbcRowSetTest.java

@@ -0,0 +1,157 @@
+package com.baeldung.jdbcrowset;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.ResultSetMetaData;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+import javax.sql.rowset.CachedRowSet;
+import javax.sql.rowset.FilteredRowSet;
+import javax.sql.rowset.JdbcRowSet;
+import javax.sql.rowset.JoinRowSet;
+import javax.sql.rowset.RowSetFactory;
+import javax.sql.rowset.RowSetProvider;
+import javax.sql.rowset.WebRowSet;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import com.sun.rowset.CachedRowSetImpl;
+import com.sun.rowset.JdbcRowSetImpl;
+import com.sun.rowset.JoinRowSetImpl;
+import com.sun.rowset.WebRowSetImpl;
+
+public class JdbcRowSetTest {
+    Statement stmt = null;
+    String username = "sa";
+    String password = "";
+    String url = "jdbc:h2:mem:testdb";
+    String sql = "SELECT * FROM customers";
+
+    @Before
+    public void setup() throws Exception {
+        Connection conn = DatabaseConfiguration.geth2Connection();
+
+        String drop = "DROP TABLE IF EXISTS customers, associates;";
+        String schema = "CREATE TABLE customers (id INT NOT NULL, name VARCHAR(50) NOT NULL, PRIMARY KEY (id)); ";
+        String schemapartb = "CREATE TABLE associates (id INT NOT NULL, name VARCHAR(50) NOT NULL, PRIMARY KEY (id));";
+        stmt = conn.createStatement();
+        stmt.executeUpdate(drop);
+        stmt.executeUpdate(schema);
+        stmt.executeUpdate(schemapartb);
+        DatabaseConfiguration.initDatabase(stmt);
+
+    }
+
+    // JdbcRowSet Example
+    @Test
+    public void createJdbcRowSet_SelectCustomers_ThenCorrect() throws Exception {
+
+        String sql = "SELECT * FROM customers";
+        JdbcRowSet jdbcRS;
+        Connection conn = DatabaseConfiguration.geth2Connection();
+        jdbcRS = new JdbcRowSetImpl(conn);
+        jdbcRS.setType(ResultSet.TYPE_SCROLL_INSENSITIVE);
+        jdbcRS.setCommand(sql);
+        jdbcRS.execute();
+        jdbcRS.addRowSetListener(new ExampleListener());
+
+        while (jdbcRS.next()) {
+            // each call to next, generates a cursorMoved event
+            System.out.println("id=" + jdbcRS.getString(1));
+            System.out.println("name=" + jdbcRS.getString(2));
+        }
+
+    }
+
+    // CachedRowSet Example
+    @Test
+    public void createCachedRowSet_DeleteRecord_ThenCorrect() throws Exception {
+
+        CachedRowSet crs = new CachedRowSetImpl();
+        crs.setUsername(username);
+        crs.setPassword(password);
+        crs.setUrl(url);
+        crs.setCommand(sql);
+        crs.execute();
+        crs.addRowSetListener(new ExampleListener());
+        while (crs.next()) {
+            if (crs.getInt("id") == 1) {
+                System.out.println("CRS found customer1 and will remove the record.");
+                crs.deleteRow();
+                break;
+            }
+        }
+    }
+
+    // WebRowSet example
+    @Test
+    public void createWebRowSet_SelectCustomers_WritetoXML_ThenCorrect() throws SQLException, IOException {
+
+        WebRowSet wrs = new WebRowSetImpl();
+        wrs.setUsername(username);
+        wrs.setPassword(password);
+        wrs.setUrl(url);
+        wrs.setCommand(sql);
+        wrs.execute();
+        FileOutputStream ostream = new FileOutputStream("customers.xml");
+        wrs.writeXml(ostream);
+    }
+
+    // JoinRowSet example
+    @Test
+    public void createCachedRowSets_DoJoinRowSet_ThenCorrect() throws Exception {
+
+        CachedRowSetImpl customers = new CachedRowSetImpl();
+        customers.setUsername(username);
+        customers.setPassword(password);
+        customers.setUrl(url);
+        customers.setCommand(sql);
+        customers.execute();
+
+        CachedRowSetImpl associates = new CachedRowSetImpl();
+        associates.setUsername(username);
+        associates.setPassword(password);
+        associates.setUrl(url);
+        String associatesSQL = "SELECT * FROM associates";
+        associates.setCommand(associatesSQL);
+        associates.execute();
+
+        JoinRowSet jrs = new JoinRowSetImpl();
+        final String ID = "id";
+        final String NAME = "name";
+        jrs.addRowSet(customers, ID);
+        jrs.addRowSet(associates, ID);
+        jrs.last();
+        System.out.println("Total rows: " + jrs.getRow());
+        jrs.beforeFirst();
+        while (jrs.next()) {
+
+            String string1 = jrs.getString(ID);
+            String string2 = jrs.getString(NAME);
+            System.out.println("ID: " + string1 + ", NAME: " + string2);
+        }
+    }
+
+    // FilteredRowSet example
+    @Test
+    public void createFilteredRowSet_filterByRegexExpression_thenCorrect() throws Exception {
+        RowSetFactory rsf = RowSetProvider.newFactory();
+        FilteredRowSet frs = rsf.createFilteredRowSet();
+        frs.setCommand("select * from customers");
+        Connection conn = DatabaseConfiguration.geth2Connection();
+        frs.execute(conn);
+        frs.setFilter(new FilterExample("^[A-C].*"));
+
+        ResultSetMetaData rsmd = frs.getMetaData();
+        int columncount = rsmd.getColumnCount();
+        while (frs.next()) {
+            for (int i = 1; i <= columncount; i++) {
+                System.out.println(rsmd.getColumnLabel(i) + " = " + frs.getObject(i) + " ");
+            }
+        }
+    }
+}

core-java/src/test/java/com/baeldung/loops/WhenUsingLoops.java

@@ -1,11 +1,38 @@
 package com.baeldung.loops;
 
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+
 import org.junit.Assert;
+import org.junit.BeforeClass;
 import org.junit.Test;
 
 public class WhenUsingLoops {
 
     private LoopsInJava loops = new LoopsInJava();
+    private static List<String> list = new ArrayList<>();
+    private static Set<String> set = new HashSet<>();
+    private static Map<String, Integer> map = new HashMap<>();
+
+    @BeforeClass
+    public static void setUp() {
+        list.add("One");
+        list.add("Two");
+        list.add("Three");
+
+        set.add("Four");
+        set.add("Five");
+        set.add("Six");
+
+        map.put("One", 1);
+        map.put("Two", 2);
+        map.put("Three", 3);
+    }
 
     @Test
     public void shouldRunForLoop() {
@@ -34,4 +61,47 @@ public class WhenUsingLoops {
         int[] actual = loops.do_while_loop();
         Assert.assertArrayEquals(expected, actual);
     }
+
+    @Test
+    public void whenUsingSimpleFor_shouldIterateList() {
+        for (int i = 0; i < list.size(); i++) {
+            System.out.println(list.get(i));
+        }
+    }
+
+    @Test
+    public void whenUsingEnhancedFor_shouldIterateList() {
+        for (String item : list) {
+            System.out.println(item);
+        }
+    }
+
+    @Test
+    public void whenUsingEnhancedFor_shouldIterateSet() {
+        for (String item : set) {
+            System.out.println(item);
+        }
+    }
+
+    @Test
+    public void whenUsingEnhancedFor_shouldIterateMap() {
+        for (Entry<String, Integer> entry : map.entrySet()) {
+            System.out.println("Key: " + entry.getKey() + " - " + "Value: " + entry.getValue());
+        }
+    }
+
+    @Test
+    public void whenUsingSimpleFor_shouldRunLabelledLoop() {
+        aa: for (int i = 1; i <= 3; i++) {
+            if (i == 1)
+                continue;
+            bb: for (int j = 1; j <= 3; j++) {
+                if (i == 2 && j == 2) {
+                    break aa;
+                }
+                System.out.println(i + " " + j);
+            }
+        }
+    }
+
 }

core-java/src/test/java/com/baeldung/nestedclass/AnonymousInner.java

@@ -2,10 +2,14 @@ package com.baeldung.nestedclass;
 
 import org.junit.Test;
 
-public class AnonymousInnerTest {
+abstract class SimpleAbstractClass {
+    abstract void run();
+}
+
+public class AnonymousInner {
 
     @Test
-    public void whenRunAnonymousClass_thenCorrect() {
+    public void run() {
         SimpleAbstractClass simpleAbstractClass = new SimpleAbstractClass() {
             void run() {
                 System.out.println("Running Anonymous Class...");

core-java/src/test/java/com/baeldung/nestedclass/Enclosing.java

@@ -0,0 +1,21 @@
+package com.baeldung.nestedclass;
+
+import org.junit.Test;
+
+public class Enclosing {
+
+    private static int x = 1;
+
+    public static class StaticNested {
+
+        private void run() {
+            System.out.println("x = " + x);
+        }
+    }
+
+    @Test
+    public void test() {
+        Enclosing.StaticNested nested = new Enclosing.StaticNested();
+        nested.run();
+    }
+}

core-java/src/test/java/com/baeldung/nestedclass/InnerClassTest.java

@@ -1,13 +0,0 @@
-package com.baeldung.nestedclass;
-
-import org.junit.Test;
-
-public class InnerClassTest {
-
-    @Test
-    public void givenInnerClassWhenInstantiating_thenCorrect() {
-        Outer outer = new Outer();
-        Outer.Inner inner = outer.new Inner();
-        inner.test();
-    }
-}

core-java/src/test/java/com/baeldung/nestedclass/LocalClassTest.java

@@ -1,12 +0,0 @@
-package com.baeldung.nestedclass;
-
-import org.junit.Test;
-
-public class LocalClassTest {
-
-    @Test
-    public void whenTestingLocalClass_thenCorrect() {
-        NewEnclosing newEnclosing = new NewEnclosing();
-        newEnclosing.run();
-    }
-}

core-java/src/test/java/com/baeldung/nestedclass/NestedClassTest.java

@@ -1,12 +0,0 @@
-package com.baeldung.nestedclass;
-
-import org.junit.Test;
-
-public class NestedClassTest {
-
-    @Test
-    public void whenInstantiatingStaticNestedClass_thenCorrect() {
-        Enclosing.Nested nested = new Enclosing.Nested();
-        nested.test();
-    }
-}