Merge pull request #37 from panos-kakos/master

Update from master

Author: panos-kakos

algorithms-modules/algorithms-sorting/src/main/java/com/baeldung/algorithms/stringsort/AlphanumericSort.java

@@ -0,0 +1,38 @@
+package com.baeldung.algorithms.stringsort;
+
+import java.util.Arrays;
+import java.util.Comparator;
+
+public class AlphanumericSort {
+
+    public static String lexicographicSort(String input) {
+        char[] stringChars = input.toCharArray();
+        Arrays.sort(stringChars);
+        return new String(stringChars);
+    }
+
+    public static String[] naturalAlphanumericSort(String[] arrayToSort) {
+        Arrays.sort(arrayToSort, new Comparator<String>() {
+            @Override
+            public int compare(String s1, String s2) {
+                return extractInt(s1) - extractInt(s2);
+            }
+
+            private int extractInt(String str) {
+                String num = str.replaceAll("\\D+", "");
+                return num.isEmpty() ? 0 : Integer.parseInt(num);
+            }
+        });
+        return arrayToSort;
+    }
+
+    public static String[] naturalAlphanumericCaseInsensitiveSort(String[] arrayToSort) {
+        Arrays.sort(arrayToSort, Comparator.comparing((String s) -> s.replaceAll("\\d", "").toLowerCase())
+            .thenComparingInt(s -> {
+                String num = s.replaceAll("\\D+", "");
+                return num.isEmpty() ? 0 : Integer.parseInt(num);
+            })
+            .thenComparing(Comparator.naturalOrder()));
+        return arrayToSort;
+    }
+}

algorithms-modules/algorithms-sorting/src/test/java/com/baeldung/algorithms/stringsort/AlphanumericSortUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.algorithms.stringsort;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class AlphanumericSortUnitTest {
+
+    @Test
+    void givenAlphanumericString_whenLexicographicSort_thenSortLettersFirst() {
+        String stringToSort = "C4B3A21";
+        String sorted = AlphanumericSort.lexicographicSort(stringToSort);
+        assertThat(sorted).isEqualTo("1234ABC");
+    }
+
+    @Test
+    void givenAlphanumericArrayOfStrings_whenAlphanumericSort_thenSortNaturalOrder() {
+        String[] arrayToSort = {"file2", "file10", "file0", "file1", "file20"};
+        String[] sorted = AlphanumericSort.naturalAlphanumericSort(arrayToSort);
+        assertThat(Arrays.toString(sorted)).isEqualTo("[file0, file1, file2, file10, file20]");
+    }
+
+    @Test
+    void givenAlphanumericArrayOfStrings_whenAlphanumericCaseInsensitveSort_thenSortNaturalOrder() {
+        String[] arrayToSort = {"a2", "A10", "b1", "B3", "A2"};
+        String[] sorted = AlphanumericSort.naturalAlphanumericCaseInsensitiveSort(arrayToSort);
+        assertThat(Arrays.toString(sorted)).isEqualTo("[A2, a2, A10, b1, B3]");
+    }
+}

core-java-modules/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpClientUnitTest.java

@@ -82,7 +82,7 @@ public void shouldFollowRedirectWhenSetToAlways() throws IOException, Interrupte
         assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
         assertThat(response.request()
             .uri()
-            .toString(), equalTo("https://stackoverflow.com/"));
+            .toString(), equalTo("https://stackoverflow.com/questions"));
     }
 
     @Test

core-java-modules/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpRequestUnitTest.java

@@ -38,7 +38,7 @@ public void shouldReturnStatusOKWhenSendGetRequest() throws IOException, Interru
     @Test
     public void shouldUseHttp2WhenWebsiteUsesHttp2() throws IOException, InterruptedException, URISyntaxException {
         HttpRequest request = HttpRequest.newBuilder()
-            .uri(new URI("https://stackoverflow.com"))
+            .uri(new URI("https://stackoverflow.com/questions"))
             .version(HttpClient.Version.HTTP_2)
             .GET()
             .build();

core-java-modules/core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpResponseUnitTest.java

@@ -34,7 +34,7 @@ public void shouldReturnStatusOKWhenSendGetRequest() throws IOException, Interru
     }
 
     @Test
-    public void shouldResponseURIDifferentThanRequestUIRWhenRedirect() throws IOException, InterruptedException, URISyntaxException {
+    public void shouldResponseURIDifferentThanRequestURIWhenRedirect() throws IOException, InterruptedException, URISyntaxException {
         HttpRequest request = HttpRequest.newBuilder()
             .uri(new URI("http://stackoverflow.com"))
             .version(HttpClient.Version.HTTP_2)
@@ -48,7 +48,7 @@ public void shouldResponseURIDifferentThanRequestUIRWhenRedirect() throws IOExce
         assertThat(request.uri()
             .toString(), equalTo("http://stackoverflow.com"));
         assertThat(response.uri()
-            .toString(), equalTo("https://stackoverflow.com/"));
+            .toString(), equalTo("https://stackoverflow.com/questions"));
     }
 
 }

core-java-modules/core-java-arrays-convert-2/README.md

@@ -0,0 +1,5 @@
+## Core Java Arrays - Conversions
+
+This module contains articles about arrays conversion in Java
+
+## Relevant Articles

core-java-modules/core-java-arrays-convert-2/pom.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-arrays-convert-2</artifactId>
+    <packaging>jar</packaging>
+    <name>core-java-arrays-convert-2</name>
+
+    <parent>
+        <artifactId>core-java-modules</artifactId>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+    </dependencies>
+
+</project>

core-java-modules/core-java-arrays-convert-2/src/test/java/com/baeldung/array/conversions/classcastexception/ClassCastExceptionUnitTest.java

@@ -0,0 +1,96 @@
+package com.baeldung.array.conversions.classcastexception;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.lang.reflect.Array;
+import java.time.Instant;
+import java.util.stream.Stream;
+
+import org.junit.jupiter.api.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class ClassCastExceptionUnitTest {
+
+    private static Logger LOG = LoggerFactory.getLogger(ClassCastExceptionUnitTest.class);
+
+    Integer[] convertObjectArray() {
+        Object[] objArray = new Object[3];
+        objArray[0] = 1;
+        objArray[1] = 2;
+        objArray[2] = 3;
+        return (Integer[]) objArray;
+    }
+
+    Integer[] getIntegerArray() {
+        Integer[] intArray = new Integer[3];
+        intArray[0] = 1;
+        intArray[1] = 2;
+        intArray[2] = 3;
+        return intArray;
+    }
+
+    Integer[] objArrayToIntArray() {
+        Object[] objArray = new Object[] { 1, 2, 3 };
+        Integer[] intArray = new Integer[objArray.length];
+        for (int i = 0; i < objArray.length; i++) {
+            intArray[i] = (Integer) objArray[i];
+        }
+        return intArray;
+    }
+
+    Integer[] objArrayToIntArrayByStream() {
+        Object[] objArray = new Object[] { 1, 2, 3 };
+        Integer[] intArray = Stream.of(objArray)
+            .toArray(Integer[]::new);
+        return intArray;
+    }
+
+    <T> T[] convertFromObjectArray(Class<T> clazz, Object[] objArray) {
+        T[] targetArray = (T[]) Array.newInstance(clazz, objArray.length);
+        for (int i = 0; i < objArray.length; i++) {
+            if (clazz.isInstance(objArray[i])) {
+                targetArray[i] = clazz.cast(objArray[i]);
+            } else {
+                throw new ClassCastException("Element #" + i + ": Cannot cast " + objArray[i].getClass()
+                    .getName() + " to " + clazz.getName());
+            }
+        }
+        return targetArray;
+    }
+
+    @Test
+    void whenCallingConvertObjectArray_thenClassCastException() {
+        Exception ex = assertThrows(ClassCastException.class, this::convertObjectArray);
+        LOG.error("The exception stacktrace:", ex);
+    }
+
+    @Test
+    void whenCallingIntegerArray_thenCorrect() {
+        assertArrayEquals(new Integer[] { 1, 2, 3 }, getIntegerArray());
+    }
+
+    @Test
+    void whenCallingObjArrayToIntArray_thenCorrect() {
+        assertArrayEquals(new Integer[] { 1, 2, 3 }, objArrayToIntArray());
+    }
+
+    @Test
+    void whenCallingObjArrayToIntArrayByStream_thenCorrect() {
+        assertArrayEquals(new Integer[] { 1, 2, 3 }, objArrayToIntArrayByStream());
+    }
+
+    @Test
+    void whenCallingSingleElementArray_thenCorrect() {
+        assertArrayEquals(new Integer[] { 1, 2, 3 }, convertFromObjectArray(Integer.class, new Object[] { 1, 2, 3 }));
+        assertArrayEquals(new String[] { "I'm Kai", "I'm Liam", "I'm Kevin" },
+            convertFromObjectArray(String.class, new Object[] { "I'm Kai", "I'm Liam", "I'm Kevin" }));
+        //class cast ex:
+        Exception ex = assertThrows(ClassCastException.class,
+            () -> convertFromObjectArray(String.class, new Object[] { "I'm Kai", Instant.now(), "I'm Kevin" }));
+        assertEquals("Element #1: Cannot cast java.time.Instant to java.lang.String", ex.getMessage());
+    }
+
+}

core-java-modules/core-java-collections-list-6/pom.xml

@@ -19,6 +19,18 @@
             <artifactId>vavr</artifactId>
             <version>${vavr.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>5.8.2</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>5.8.2</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <properties>

core-java-modules/core-java-collections-list-6/src/main/java/com/baeldung/listtostring/DoublyLinkedList.java

@@ -0,0 +1,46 @@
+package com.baeldung.listtostring;
+
+public class DoublyLinkedList {
+    DoublyLinkedListNode head;
+    DoublyLinkedListNode tail;
+
+    public void add(Integer data) {
+        DoublyLinkedListNode newNode = new DoublyLinkedListNode(data);
+        if (head == null) {
+            head = newNode;
+            tail = newNode;
+        } else {
+            tail.next = newNode;
+            newNode.prev = tail;
+            tail = newNode;
+        }
+    }
+
+    public static String customToString(DoublyLinkedList list) {
+        StringBuilder sb = new StringBuilder();
+        sb.append("Custom Doubly LinkedList: ");
+        if (list.head == null) {
+            sb.append("Empty List");
+        } else {
+            DoublyLinkedListNode currentNode = list.head;
+            while (currentNode != null) {
+                sb.append(currentNode.data).append(" - ");
+                currentNode = currentNode.next;
+            }
+            sb.delete(sb.length() - 3, sb.length());  
+        }
+        return sb.toString();
+    }
+
+    public static void main(String[] args) {
+        DoublyLinkedList idsList = new DoublyLinkedList();
+        idsList.add(101);
+        idsList.add(102);
+        idsList.add(103);
+
+        System.out.println(customToString(idsList));
+
+        DoublyLinkedList emptyList = new DoublyLinkedList();
+        System.out.println(customToString(emptyList)); 
+    }
+}