- \n
- Major enhancement at version 5<\/a>, including generic type.<\/li>\n
- Added more interfaces and classes at version 6<\/a>, including
Deque<\/code>,BlockingDeque<\/code>,NavigableSet<\/code>,NavigableMap<\/code>,ConcurrentNavigableMap<\/code>, etc.<\/li>\n- Added a new
TransferQueue<\/code> interface at version 7<\/a>.<\/li>\nCollection<\/code> added theforeach(Consumer<? super T>> action)<\/code> method at version 8<\/a>.<\/li>\n- Added factory methods for creating immutable lists at version 9<\/a>, such as
static<\/code>of()<\/code> method. <\/li>\nList<\/code> addedstatic<\/code>copyOf()<\/code> method at version 10<\/a>. <\/li>\nCollection<\/code> added a new default methodtoArray(IntFunction<T[]> generator)<\/code> at version 11<\/a>.<\/li>\n<\/ul>\nYou can also check this tutorial in the following video:<\/p>\n
\n![\"\"](\"https:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2022\/07\/Java-Collections-Tutorial-1024x576.jpg\")
<\/a>Java Collections Tutorial – video<\/figcaption><\/figure>\n<\/div>\n In this example, I will create several test classes to demonstrate how to use the most commonly used interfaces:
List<\/code>,Set<\/code>,Queue<\/code> and classes:ArrayList<\/code>,LinkedList<\/code>,Vector<\/code>,Stack<\/code>,HashSet<\/code>,TreeSet<\/code>.<\/p>\n\n![\"Java](\"https:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2019\/08\/collections.jpg\")
Figure 1 Collections<\/figcaption><\/figure>\n<\/div>\n 2. Technologies Used<\/h2>\n
The example code in this article was built and run using:<\/p>\n
- \n
- Java 11<\/li>\n
- Maven 3.3.9<\/li>\n
- Eclipse Oxygen<\/li>\n
- Logback 1.2.3<\/li>\n<\/ul>\n
3. Maven Project<\/h2>\n
3.1 Pom.xml<\/h3>\n
Pom.xml<\/code> manages the project dependencies.<\/p>\npom.xml<\/em><\/span>\n<\/p>\n
<project xmlns=\"http:\/\/maven.apache.org\/POM\/4.0.0\"\n\txmlns:xsi=\"http:\/\/www.w3.org\/2001\/XMLSchema-instance\"\n\txsi:schemaLocation=\"http:\/\/maven.apache.org\/POM\/4.0.0 http:\/\/maven.apache.org\/xsd\/maven-4.0.0.xsd\">\n\t<modelVersion>4.0.0<\/modelVersion>\n\t<groupId>jcg.zheng.demo<\/groupId>\n\t<artifactId>java-collections-demo<\/artifactId>\n\t<version>0.0.1-SNAPSHOT<\/version>\n\t<build>\n\t\t<sourceDirectory>src<\/sourceDirectory>\n\t\t<plugins>\n\t\t\t<plugin>\n\t\t\t\t<artifactId>maven-compiler-plugin<\/artifactId>\n\t\t\t\t<version>3.8.0<\/version>\n\t\t\t\t<configuration>\n\t\t\t\t\t<release>11<\/release>\n\t\t\t\t<\/configuration>\n\t\t\t<\/plugin>\n\t\t<\/plugins>\n\t<\/build>\n\t<dependencies>\n\t\t<dependency>\n\t\t\t<groupId>junit<\/groupId>\n\t\t\t<artifactId>junit<\/artifactId>\n\t\t\t<version>4.12<\/version>\n\t\t<\/dependency>\n\t\t<dependency>\n\t\t\t<groupId>ch.qos.logback<\/groupId>\n\t\t\t<artifactId>logback-access<\/artifactId>\n\t\t\t<version>1.2.3<\/version>\n\t\t<\/dependency>\n\t\t<dependency>\n\t\t\t<groupId>ch.qos.logback<\/groupId>\n\t\t\t<artifactId>logback-classic<\/artifactId>\n\t\t\t<version>1.2.3<\/version>\n\t\t<\/dependency>\n\t\t<dependency>\n\t\t\t<groupId>ch.qos.logback<\/groupId>\n\t\t\t<artifactId>logback-core<\/artifactId>\n\t\t\t<version>1.2.3<\/version>\n\t\t<\/dependency>\n\t<\/dependencies>\n<\/project><\/pre>\n
3.2 SomeData<\/h3>\n
Java collection classes work with Object<\/a>, not the primitive data type. In this step, I will create a
SomeData<\/code> class which implements theComparable<\/code> interface.<\/p>\nSomeData.java<\/em><\/span>\n<\/p>\n
package jcg.zheng.demo.data;\n\nimport java.io.Serializable;\n\npublic class SomeData implements Comparable , Serializable {\n\n\tprivate static final long serialVersionUID = -5243901184267064976L;\n\n\tprivate int id;\n\n\tprivate String name;\n\n\t@Override\n\tpublic boolean equals(Object obj) {\n\t\tif (this == obj)\n\t\t\treturn true;\n\t\tif (obj == null)\n\t\t\treturn false;\n\t\tif (getClass() != obj.getClass())\n\t\t\treturn false;\n\t\tSomeData other = (SomeData) obj;\n\t\tif (id != other.id)\n\t\t\treturn false;\n\t\tif (name == null) {\n\t\t\tif (other.name != null)\n\t\t\t\treturn false;\n\t\t} else if (!name.equals(other.name))\n\t\t\treturn false;\n\t\treturn true;\n\t}\n\n\tpublic int getId() {\n\t\treturn id;\n\t}\n\n\tpublic String getName() {\n\t\treturn name;\n\t}\n\n\t@Override\n\tpublic int hashCode() {\n\t\tfinal int prime = 31;\n\t\tint result = 1;\n\t\tresult = prime * result + id;\n\t\tresult = prime * result + ((name == null) ? 0 : name.hashCode());\n\t\treturn result;\n\t}\n\n\tpublic void setId(int id) {\n\t\tthis.id = id;\n\t}\n\n\tpublic void setName(String name) {\n\t\tthis.name = name;\n\t}\n\n\t@Override\n\tpublic String toString() {\n\t\treturn \"SomeData [name=\" + name + \", id=\" + id + \"]\";\n\t}\n\n\t@Override\n\tpublic int compareTo(SomeData other) {\n\t\tint byName = this.name.compareTo(other.getName());\n\t\treturn byName;\n\t}\n\n}\n<\/pre>\n4. Abstract Test Classes<\/h2>\n
In this step, I will create three abstract test classes:<\/p>\n
- \n
CollectionBase_POJOTest<\/code> – It demonstrates how toadd<\/code>,remove<\/code>,clear<\/code>,contains<\/code>,getSize<\/code>,foreach<\/code> for aCollection<\/code> ofSomeData<\/code> objects. <\/li>\nCollectionBase_StringTest<\/code> – It does the same as above class but forString<\/code> objects.<\/li>\nListBase_StringTest<\/code> – It extends fromCollectionBase_StringTest<\/code> with additional test methods for theList<\/code> interface withString<\/code> objects.<\/li>\n<\/ul>\n4.1 CollectionBase_StringTest<\/h3>\n
The
Collection<\/code> interface includes methods to add, remove, and retrieve elements from a collection. It checks the element’s existence with thecontains<\/code> method. In this example, I will create a test class which demonstrates how to use these methods forString<\/code> objects.<\/p>\nCollectionBase_StringTest.java<\/em><\/span>\n<\/p>\n
package jcg.zheng.demo;\n\nimport static org.junit.Assert.assertEquals;\nimport static org.junit.Assert.assertFalse;\nimport static org.junit.Assert.assertTrue;\n\nimport java.util.Arrays;\nimport java.util.Collection;\nimport java.util.Iterator;\n\nimport org.junit.After;\nimport org.junit.FixMethodOrder;\nimport org.junit.Test;\nimport org.junit.runners.MethodSorters;\nimport org.slf4j.Logger;\n\n@FixMethodOrder(MethodSorters.NAME_ASCENDING)\npublic abstract class CollectionBase_StringTest {\n\n\tprotected Collection<String> colItems;\n\n\tprotected Logger logger;\n\n\t@Test\n\tpublic void Collection_add() {\n\t\tcolItems.add(\"new Item\");\n\t\tassertEquals(5, colItems.size());\n\n\t\tlogger.info(\"The arraycolItems contains the following elements: \" + colItems);\n\t}\n\n\t@After\n\tpublic void Collection_clear() {\n\t\tcolItems.clear();\n\t\tassertTrue(colItems.isEmpty());\n\t}\n\n\t@Test\n\tpublic void Collection_contains() {\n\t\tassertTrue(colItems.contains(\"Item1\"));\n\t\tassertFalse(colItems.contains(\"Item5\"));\n\t}\n\n\t@Test\n\tpublic void Collection_getSize() {\n\t\tassertEquals(4, colItems.size());\n\t}\n\n\t@Test\n\tpublic void Collection_isEmpty() {\n\t\tassertFalse(colItems.isEmpty());\n\t}\n\n\t@Test\n\tpublic void Collection_loop_via_for() {\n\t\tlogger.info(\"Retrieving items using for loop\");\n\t\tfor (String str : colItems) {\n\t\t\tlogger.info(\"Item is: \" + str);\n\t\t}\n\t}\n\n\t@Test\n\tpublic void Collection_loop_via_foreach_java8() {\n\t\tlogger.info(\"Retrieving items using Java 8 Stream\");\n\t\tcolItems.forEach((item) -> {\n\t\t\tlogger.info(item);\n\t\t});\n\t}\n\n\t@Test\n\tpublic void Collection_loop_via_iterator_next() {\n\t\tlogger.info(\"Retrieving items using iterator\");\n\t\tfor (Iterator<String> it = colItems.iterator(); it.hasNext();) {\n\t\t\tlogger.info(\"Item is: \" + it.next());\n\t\t}\n\t}\n\n\t@Test\n\tpublic void Collection_loop_via_iterator_while() {\n\t\tIterator<String> it = colItems.iterator();\n\t\tlogger.info(\"Retrieving items using iterator\");\n\t\twhile (it.hasNext()) {\n\t\t\tlogger.info(\"Item is: \" + it.next());\n\t\t}\n\t}\n\n\t@Test\n\tpublic void Collection_remove() {\n\t\tboolean removed = colItems.remove(\"Item1\");\n\t\tassertTrue(removed);\n\t\tassertEquals(3, colItems.size());\n\n\t\tcolItems.remove(\"Item3\");\n\t\tassertEquals(2, colItems.size());\n\t}\n\n\t@Test\n\tpublic void Collection_remove_via_iterator_remove() {\n\t\tlogger.info(\"Removing items using iterator\");\n\t\tfor (Iterator<String> it = colItems.iterator(); it.hasNext();) {\n\t\t\tString item = it.next();\n\t\t\tlogger.info(\"Item is: \" + item);\n\t\t\tit.remove();\n\t\t\tassertFalse(colItems.contains(item));\n\t\t}\n\n\t\tassertTrue(colItems.isEmpty());\n\t}\n\n\t@Test\n\tpublic void Collection_toArray_default_java11() {\n\t\tString[] simpleArray = colItems.toArray(new String[colItems.size()]);\n\t\tlogger.info(\"The array created after the conversion of our arraycolItems is: \" + Arrays.toString(simpleArray));\n\n\t\tString[] testArr = colItems.toArray(size -> new String[size]);\n\t\tlogger.info(\"default toArray(intfunction):\" + Arrays.toString(testArr));\n\t}\n}<\/pre>\nNote<\/strong>: the
colItems<\/code> variable is a type ofCollection<String><\/code><\/p>\n4.2 CollectionBase_POJOTest<\/h3>\n
In this step, I will create a
CollectionBase_POJOTest<\/code> class which has the same methods as theCollectionBase_StringTest<\/code> class but with theSomeData<\/code> type.<\/p>\nCollectionBase_POJOTest.java<\/em><\/span>\n<\/p>\n
package jcg.zheng.demo;\n\nimport static org.junit.Assert.assertEquals;\nimport static org.junit.Assert.assertFalse;\nimport static org.junit.Assert.assertTrue;\n\nimport java.util.Arrays;\nimport java.util.Collection;\nimport java.util.Iterator;\n\nimport org.junit.After;\nimport org.junit.FixMethodOrder;\nimport org.junit.Test;\nimport org.junit.runners.MethodSorters;\nimport org.slf4j.Logger;\n\nimport jcg.zheng.demo.data.SomeData;\n\n@FixMethodOrder(MethodSorters.NAME_ASCENDING)\npublic abstract class CollectionBase_POJOTest {\n\n\tCollection<SomeData> list;\n\n\tprotected Logger logger;\n\n\tprotected SomeData buildSomeData(int id, String name) {\n\t\tSomeData sd = new SomeData();\n\t\tsd.setId(id);\n\t\tsd.setName(name);\n\t\treturn sd;\n\t}\n\n\t@Test\n\tpublic void Collection_add() {\n\t\tlist.add(buildSomeData(1, \"test\"));\n\t\tassertEquals(5, list.size());\n\n\t\tlogger.info(\"The arraylist contains the following elements: \" + list);\n\t}\n\n\t@After\n\tpublic void Collection_clear() {\n\t\tlist.clear();\n\t\tassertTrue(list.isEmpty());\n\t}\n\n\t@Test\n\tpublic void Collection_contains() {\n\t\tassertTrue(list.contains(buildSomeData(1, \"Item1\")));\n\t\tassertFalse(list.contains(buildSomeData(5, \"Item5\")));\n\t}\n\n\t@Test\n\tpublic void Collection_getSize() {\n\t\tassertEquals(4, list.size());\n\t}\n\n\t@Test\n\tpublic void Collection_isEmpty() {\n\t\tassertFalse(list.isEmpty());\n\t}\n\n\t@Test\n\tpublic void Collection_loop_via_for() {\n\t\tlogger.info(\"Retrieving items using for loop\");\n\t\tfor (SomeData str : list) {\n\t\t\tlogger.info(\"Item is: \" + str);\n\t\t}\n\t}\n\n\t@Test\n\tpublic void Collection_loop_via_foreach_lambda() {\n\t\tlogger.info(\"Retrieving items using Java 8 Stream\");\n\t\tlist.forEach((item) -> {\n\t\t\tlogger.info(item.toString());\n\t\t});\n\t}\n\n\t@Test\n\tpublic void Collection_loop_via_iterator_for() {\n\t\tlogger.info(\"Retrieving items using iterator\");\n\t\tfor (Iterator<SomeData> it = list.iterator(); it.hasNext();) {\n\t\t\tlogger.info(\"Item is: \" + it.next().toString());\n\t\t}\n\t}\n\n\t@Test\n\tpublic void Collection_loop_via_iterator_while() {\n\t\tIterator<SomeData> it = list.iterator();\n\t\tlogger.info(\"Retrieving items using iterator\");\n\t\twhile (it.hasNext()) {\n\t\t\tlogger.info(\"Item is: \" + it.next().toString());\n\t\t}\n\t}\n\n\t@Test\n\tpublic void Collection_remove() {\n\t\tlist.remove(buildSomeData(3, \"Item3\"));\n\t\tassertEquals(3, list.size());\n\t}\n\n\t@Test\n\tpublic void Collection_toArray() {\n\t\tSomeData[] simpleArray = list.toArray(new SomeData[list.size()]);\n\t\tlogger.info(\"The array created after the conversion of our arraylist is: \" + Arrays.toString(simpleArray));\n\t}\n}<\/pre>\nNote<\/strong>: the
list<\/code> variable is a type ofCollection<SomeData><\/code><\/p>\n4.3 ListBase_StringTest<\/h3>\n
The List<\/a> interface extends from the Collection<\/a> interface with additional methods. In this step, I will demonstrate how to add, remove, and retrieve at a given index position for a
List<\/code> ofString<\/code>. I will also demonstrate two Collections algorithms with thesort<\/code> andbinarySearch<\/code> methods.<\/p>\nListBase_StringTest.java<\/em><\/span>\n<\/p>\n
package jcg.zheng.demo;\n\nimport static org.junit.Assert.assertEquals;\nimport static org.junit.Assert.assertTrue;\n\nimport java.util.Collections;\nimport java.util.List;\n\nimport org.junit.Test;\n\npublic abstract class ListBase_StringTest extends CollectionBase_StringTest {\n\n\tprotected List<String> listItems;\n\n\t@Test\n\tpublic void Collections_sort_binarySearch() {\n\t\tlistItems.add(\"Tom\");\n\t\tlistItems.add(\"Mary\");\n\t\tlistItems.add(\"Shan\");\n\t\tlistItems.add(\"Zheng\");\n\n\t\tCollections.sort(listItems);\n\t\tassertEquals(\"Mary\", listItems.get(0));\n\t\tassertEquals(\"Shan\", listItems.get(1));\n\t\tassertEquals(\"Tom\", listItems.get(2));\n\t\tassertEquals(\"Zheng\", listItems.get(3));\n\t\tlogger.info(\"Sorted List\");\n\t\tfor (int i = 0; i < listItems.size(); i++) {\n\t\t\tlogger.info(\"Index: \" + i + \" - Item: \" + listItems.get(i));\n\t\t}\n\n\t\tint foundTom = Collections.binarySearch(listItems, \"Tom\");\n\t\tassertEquals(2, foundTom);\n\t}\n\n\t@Test\n\tpublic void List_can_add_get_remove_via_index() {\n\n\t\tlistItems.add(0, \"Mary\");\n\t\tassertEquals(1, listItems.size());\n\n\t\tint pos = listItems.indexOf(\"Mary\");\n\t\tassertEquals(0, pos);\n\n\t\tString item0 = listItems.get(0);\n\t\tassertEquals(\"Mary\", item0);\n\n\t\tlistItems.set(0, \"Zheng\");\n\t\tassertEquals(\"Zheng\", listItems.get(0));\n\n\t\tlistItems.remove(0);\n\t\tassertTrue(listItems.isEmpty());\n\n\t}\n\n\t@Test\n\tpublic void List_copyOf_java10() {\n\t\tlistItems.add(\"JCG\");\n\t\tlistItems.add(\"Demo\");\n\n\t\tList<String> copiedValues = List.copyOf(listItems);\n\t\tassertEquals(2, copiedValues.size());\n\t}\n\n\t@Test\n\tpublic void List_loop_via_for_get_index() {\n\t\tlistItems.add(\"Tom\");\n\t\tlistItems.add(\"Mary\");\n\t\tlistItems.add(\"Shan\");\n\t\tlistItems.add(\"Zheng\");\n\n\t\tlogger.info(\"Retrieving items with loop using index and size list\");\n\t\tfor (int i = 0; i < listItems.size(); i++) {\n\t\t\tlogger.info(\"Index: \" + i + \" - Item: \" + listItems.get(i));\n\t\t}\n\t}\n\n\t@Test\n\tpublic void List_of_java9() {\n\t\tList<String> emptyList = List.of();\n\t\tassertTrue(emptyList.isEmpty());\n\n\t\tList<String> itemList = List.of(\"Mary\", \"Zheng\", \"Developer\");\n\t\tassertEquals(3, itemList.size());\n\t}\n\n}\n<\/pre>\nNote<\/strong>: the
listItems<\/code> variable is a type ofList<String><\/code><\/p>\n5. Test Classes<\/h2>\n
In this step, I will create test classes for the commonly used
Collection<\/code> classes. Each test class is extends from one of the three abstract test classes with its unique operations. The test method is named as{$InterfaceName}_{$MethodName}<\/code>. <\/p>\n5.1 ArrayList_StringTest<\/h3>\n
ArrayList<\/a> implements List<\/a>, Serializable<\/a>, Cloneable<\/a>, Iterable<\/a>, Collection<\/a>, and RandomAccess<\/a> interfaces. It is used to store dynamically sized collection of elements.
<\/div> <\/div><\/p>\nIn this step, I will create an
ArrayList_StringTest<\/code> class which extends fromListBase_StringTest<\/code>. <\/p>\nIn the
setup_list_with_4_items<\/code> method, it will create anArrayList<\/code> instance and add four items. This method is also annotated with@Before<\/code> annotation so it will be called for each test method.<\/p>\nIn the
ArrayList_clone<\/code> method, it will clone an array list.<\/p>\nArrayList_StringTest.java<\/em><\/span>\n<\/p>\n
package jcg.zheng.demo;\n\nimport static org.junit.Assert.assertEquals;\nimport static org.junit.Assert.assertTrue;\n\nimport java.util.ArrayList;\n\nimport org.junit.Before;\nimport org.junit.Test;\nimport org.slf4j.LoggerFactory;\n\npublic class ArrayList_StringTest extends ListBase_StringTest {\n\n @SuppressWarnings(\"unchecked\")\n @Test\n public void Object_clone() {\n ArrayList<String> arrList = (ArrayList<String>) listItems;\n arrList.add(\"Mary\");\n arrList.add(\"JCG\");\n\n ArrayList<String> cloneArr = (ArrayList<String>) arrList.clone();\n assertEquals(2, cloneArr.size());\n }\n\n @Before\n public void setup_list_with_4_items() {\n logger = LoggerFactory.getLogger(this.getClass());\n\n colItems = new ArrayList<String>();\n assertTrue(colItems.isEmpty());\n\n colItems.add(\"Item1\");\n assertEquals(1, colItems.size());\n colItems.add(\"Item2\");\n assertEquals(2, colItems.size());\n colItems.add(\"Item3\");\n assertEquals(3, colItems.size());\n colItems.add(\"Item4\");\n assertEquals(4, colItems.size());\n\n listItems = new ArrayList<String>();\n listItems.addAll(colItems);\n assertEquals(4, listItems.size());\n listItems.clear();\n\n }\n\n}\n<\/pre>\nExecute
mvn test -Dtest=ArrayList_StringTest<\/code><\/p>\nOutput<\/em><\/span>\n<\/p>\n
-------------------------------------------------------\n T E S T S\n-------------------------------------------------------\nRunning jcg.zheng.demo.ArrayList_StringTest\n05:19:33.334 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Retrieving items with loop using index and size list\n05:19:33.377 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Index: 0 - Item: Tom\n05:19:33.377 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Index: 1 - Item: Mary\n05:19:33.377 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Index: 2 - Item: Shan\n05:19:33.377 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Index: 3 - Item: Zheng\n05:19:33.381 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Sorted List\n05:19:33.383 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Index: 0 - Item: Mary\n05:19:33.384 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Index: 1 - Item: Shan\n05:19:33.384 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Index: 2 - Item: Tom\n05:19:33.390 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Index: 3 - Item: Zheng\n05:19:33.417 [main] INFO jcg.zheng.demo.ArrayList_StringTest - The arraycolItems contains the following elements: [Item1, Item2, Item3, Item4, new Item]\n05:19:33.425 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Retrieving items using for loop\n05:19:33.426 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item1\n05:19:33.427 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item2\n05:19:33.427 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item3\n05:19:33.427 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item4\n05:19:33.428 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Retrieving items using Java 8 Stream\n05:19:33.431 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item1\n05:19:33.431 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item2\n05:19:33.431 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item3\n05:19:33.431 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item4\n05:19:33.432 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Retrieving items using iterator\n05:19:33.432 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item1\n05:19:33.433 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item2\n05:19:33.433 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item3\n05:19:33.433 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item4\n05:19:33.434 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Retrieving items using iterator\n05:19:33.435 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item1\n05:19:33.436 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item2\n05:19:33.437 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item3\n05:19:33.437 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item4\n05:19:33.445 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Removing items using iterator\n05:19:33.446 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item1\n05:19:33.446 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item2\n05:19:33.447 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item3\n05:19:33.448 [main] INFO jcg.zheng.demo.ArrayList_StringTest - Item is: Item4\n05:19:33.455 [main] INFO jcg.zheng.demo.ArrayList_StringTest - The array created after the conversion of our arraycolItems is: [Item1, Item2, Item3, Item4]\n05:19:33.458 [main] INFO jcg.zheng.demo.ArrayList_StringTest - default toArray(intfunction):[Item1, Item2, Item3, Item4]\nTests run: 17, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.526 sec\n\nResults :\n\nTests run: 17, Failures: 0, Errors: 0, Skipped: 0\n\n[INFO] ------------------------------------------------------------------------\n[INFO] BUILD SUCCESS\n[INFO] ------------------------------------------------------------------------\n[INFO] Total time: 11.850 s\n[INFO] Finished at: 2019-08-04T05:19:33-05:00\n[INFO] ------------------------------------------------------------------------\n\nC:\\MaryZheng\\Workspaces\\jdk12\\java-collections-demo><\/pre>\n
5.2 LinkedList_StringTest<\/h3>\n
LinkedList<\/a> implements Serializable<\/a>, Cloneable<\/a>, Iterable<\/a>, Collection<\/a>, List<\/a> and Queue<\/a> interfaces. It models the linked-list data structure<\/a>.<\/p>\n
In this step, I will create a
LinkedList_StringTest<\/code> class which extends fromListBase_StringTest<\/code>. <\/p>\nIn the
setup_colItem_with_4_items<\/code> method, it will create aLinkedList<\/code> instance and add four items. This method is also annotated with@Before<\/code> annotation so it will be called for each test method.<\/p>\nIn the
DeQue_peekFirst_peekLast<\/code> method, it will find the first element and last element from theDeQue<\/code> interface’s methods.<\/p>\nIn the
DeQue_peek<\/code> method, it will find the head element fromDeque<\/code>‘s method.<\/p>\nLinkedList_StringTest.java<\/em><\/span>\n<\/p>\n
package jcg.zheng.demo;\n\nimport static org.junit.Assert.assertEquals;\nimport static org.junit.Assert.assertTrue;\n\nimport java.util.LinkedList;\n\nimport org.junit.Before;\nimport org.junit.Test;\nimport org.slf4j.LoggerFactory;\n\npublic class LinkedList_StringTest extends ListBase_StringTest {\n\n @Test\n public void DeQue_peekFirst_peekLast() {\n LinkedList<String> linkedLst = (LinkedList<String>) listItems;\n linkedLst.add(\"Mary\");\n linkedLst.add(\"Zheng\");\n\n assertEquals(\"Mary\", linkedLst.peekFirst());\n assertEquals(\"Zheng\", linkedLst.peekLast());\n\n assertEquals(\"Mary\", linkedLst.peek());\n }\n\n @Test\n public void DeQue_peek() {\n LinkedList<String> linkedLst = (LinkedList<String>) listItems;\n linkedLst.add(\"Mary\");\n linkedLst.add(\"Zheng\");\n\n assertEquals(\"Mary\", linkedLst.peek());\n }\n\n @Before\n public void setup_colItems_with_4_items() {\n logger = LoggerFactory.getLogger(this.getClass());\n\n colItems = new LinkedList<String>();\n assertTrue(colItems.isEmpty());\n\n colItems.add(\"Item1\");\n assertEquals(1, colItems.size());\n colItems.add(\"Item2\");\n assertEquals(2, colItems.size());\n colItems.add(\"Item3\");\n assertEquals(3, colItems.size());\n colItems.add(\"Item4\");\n assertEquals(4, colItems.size());\n\n listItems = new LinkedList<String>();\n listItems.addAll(colItems);\n assertEquals(4, listItems.size());\n listItems.clear();\n }\n\n}\n<\/pre>\nExecute
mvn test -Dtest=LinkedList_StringTest<\/code><\/p>\nOutput<\/em><\/span>\n<\/p>\n
-------------------------------------------------------\n T E S T S\n-------------------------------------------------------\nRunning jcg.zheng.demo.LinkedList_StringTest\n05:22:22.802 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Retrieving items with loop using index and size list\n05:22:22.865 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Index: 0 - Item: Tom\n05:22:22.866 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Index: 1 - Item: Mary\n05:22:22.867 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Index: 2 - Item: Shan\n05:22:22.869 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Index: 3 - Item: Zheng\n05:22:22.873 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Sorted List\n05:22:22.875 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Index: 0 - Item: Mary\n05:22:22.876 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Index: 1 - Item: Shan\n05:22:22.877 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Index: 2 - Item: Tom\n05:22:22.878 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Index: 3 - Item: Zheng\n05:22:22.908 [main] INFO jcg.zheng.demo.LinkedList_StringTest - The arraycolItems contains the following elements: [Item1, Item2, Item3, Item4, new Item]\n05:22:22.914 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Retrieving items using for loop\n05:22:22.915 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item1\n05:22:22.917 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item2\n05:22:22.918 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item3\n05:22:22.918 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item4\n05:22:22.920 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Retrieving items using Java 8 Stream\n05:22:22.921 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item1\n05:22:22.922 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item2\n05:22:22.922 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item3\n05:22:22.922 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item4\n05:22:22.922 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Retrieving items using iterator\n05:22:22.923 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item1\n05:22:22.923 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item2\n05:22:22.924 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item3\n05:22:22.925 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item4\n05:22:22.925 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Retrieving items using iterator\n05:22:22.926 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item1\n05:22:22.926 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item2\n05:22:22.926 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item3\n05:22:22.926 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item4\n05:22:22.930 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Removing items using iterator\n05:22:22.930 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item1\n05:22:22.931 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item2\n05:22:22.931 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item3\n05:22:22.932 [main] INFO jcg.zheng.demo.LinkedList_StringTest - Item is: Item4\n05:22:22.934 [main] INFO jcg.zheng.demo.LinkedList_StringTest - The array created after the conversion of our arraycolItems is: [Item1, Item2, Item3, Item4]\n05:22:22.936 [main] INFO jcg.zheng.demo.LinkedList_StringTest - default toArray(intfunction):[Item1, Item2, Item3, Item4]\nTests run: 18, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.726 sec\n\nResults :\n\nTests run: 18, Failures: 0, Errors: 0, Skipped: 0\n\n[INFO] ------------------------------------------------------------------------\n[INFO] BUILD SUCCESS\n[INFO] ------------------------------------------------------------------------\n[INFO] Total time: 13.643 s<\/pre>\n
5.3 Vector_StringTestBase<\/h3>\n
Vector<\/a> implements Serializable<\/a>, Cloneable<\/a>, Iterable<\/a>, Collection<\/a>, List<\/a>, and RandomAccess<\/a> interfaces. It implements a grow-able array of objects.<\/p>\n
In this step, I will create a
Vector_StringTest<\/code> class which extends fromListBase_StringTest<\/code>. <\/p>\nIn the
setup_colItems_with_4_items<\/code> method, it will create aVector<\/code> instance and add four items. This method is also annotated with@Before<\/code> annotation so it will be called for each test method.<\/p>\nIn the
Vector_firstElement_lastElement<\/code> method, it will find the first and last elements.<\/p>\nVector_StringTest.java<\/em><\/span>\n<\/p>\n
package jcg.zheng.demo;\n\nimport static org.junit.Assert.assertEquals;\nimport static org.junit.Assert.assertTrue;\n\nimport java.util.Vector;\n\nimport org.junit.Before;\nimport org.junit.Test;\nimport org.slf4j.LoggerFactory;\n\npublic class Vector_StringTest extends ListBase_StringTest {\n\n\t@Before\n\tpublic void setup_colItems_with_4_items() {\n\t\tlogger = LoggerFactory.getLogger(this.getClass());\n\n\t\tcolItems = new Vector<String>();\n\t\tassertTrue(colItems.isEmpty());\n\n\t\tcolItems.add(\"Item1\");\n\t\tassertEquals(1, colItems.size());\n\t\tcolItems.add(\"Item2\");\n\t\tassertEquals(2, colItems.size());\n\t\tcolItems.add(\"Item3\");\n\t\tassertEquals(3, colItems.size());\n\t\tcolItems.add(\"Item4\");\n\t\tassertEquals(4, colItems.size());\n\n\t\tlistItems = new Vector<String>();\n\t\tlistItems.addAll(colItems);\n\t\tassertEquals(4, listItems.size());\n\t\tlistItems.clear();\n\t}\n\n\t@Test\n\tpublic void Vector_firstElement_lastElement() {\n\t\tVector<String> vectorObj = (Vector<String>) listItems;\n\n\t\tvectorObj.add(\"Mary\");\n\t\tvectorObj.add(\"Zheng\");\n\t\tassertEquals(\"Mary\", vectorObj.firstElement());\n\t\tassertEquals(\"Zheng\", vectorObj.lastElement());\n\t}\n\n}\n<\/pre>\nExecute
mvn test -Dtest=Vector_StringTest<\/code><\/p>\nOutput<\/em><\/span>\n<\/p>\n
-------------------------------------------------------\n T E S T S\n-------------------------------------------------------\nRunning jcg.zheng.demo.Vector_StringTest\n05:25:12.397 [main] INFO jcg.zheng.demo.Vector_StringTest - Retrieving items with loop using index and size list\n05:25:12.443 [main] INFO jcg.zheng.demo.Vector_StringTest - Index: 0 - Item: Tom\n05:25:12.443 [main] INFO jcg.zheng.demo.Vector_StringTest - Index: 1 - Item: Mary\n05:25:12.443 [main] INFO jcg.zheng.demo.Vector_StringTest - Index: 2 - Item: Shan\n05:25:12.443 [main] INFO jcg.zheng.demo.Vector_StringTest - Index: 3 - Item: Zheng\n05:25:12.447 [main] INFO jcg.zheng.demo.Vector_StringTest - Sorted List\n05:25:12.448 [main] INFO jcg.zheng.demo.Vector_StringTest - Index: 0 - Item: Mary\n05:25:12.448 [main] INFO jcg.zheng.demo.Vector_StringTest - Index: 1 - Item: Shan\n05:25:12.449 [main] INFO jcg.zheng.demo.Vector_StringTest - Index: 2 - Item: Tom\n05:25:12.449 [main] INFO jcg.zheng.demo.Vector_StringTest - Index: 3 - Item: Zheng\n05:25:12.488 [main] INFO jcg.zheng.demo.Vector_StringTest - The arraycolItems contains the following elements: [Item1, Item2, Item3, Item4, new Item]\n05:25:12.493 [main] INFO jcg.zheng.demo.Vector_StringTest - Retrieving items using for loop\n05:25:12.498 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item1\n05:25:12.498 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item2\n05:25:12.498 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item3\n05:25:12.498 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item4\n05:25:12.500 [main] INFO jcg.zheng.demo.Vector_StringTest - Retrieving items using Java 8 Stream\n05:25:12.501 [main] INFO jcg.zheng.demo.Vector_StringTest - Item1\n05:25:12.502 [main] INFO jcg.zheng.demo.Vector_StringTest - Item2\n05:25:12.502 [main] INFO jcg.zheng.demo.Vector_StringTest - Item3\n05:25:12.502 [main] INFO jcg.zheng.demo.Vector_StringTest - Item4\n05:25:12.503 [main] INFO jcg.zheng.demo.Vector_StringTest - Retrieving items using iterator\n05:25:12.504 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item1\n05:25:12.504 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item2\n05:25:12.504 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item3\n05:25:12.504 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item4\n05:25:12.505 [main] INFO jcg.zheng.demo.Vector_StringTest - Retrieving items using iterator\n05:25:12.507 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item1\n05:25:12.508 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item2\n05:25:12.508 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item3\n05:25:12.508 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item4\n05:25:12.516 [main] INFO jcg.zheng.demo.Vector_StringTest - Removing items using iterator\n05:25:12.517 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item1\n05:25:12.517 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item2\n05:25:12.518 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item3\n05:25:12.518 [main] INFO jcg.zheng.demo.Vector_StringTest - Item is: Item4\n05:25:12.522 [main] INFO jcg.zheng.demo.Vector_StringTest - The array created after the conversion of our arraycolItems is: [Item1, Item2, Item3, Item4]\n05:25:12.524 [main] INFO jcg.zheng.demo.Vector_StringTest - default toArray(intfunction):[Item1, Item2, Item3, Item4]\nTests run: 17, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.518 sec\n\nResults :\n\nTests run: 17, Failures: 0, Errors: 0, Skipped: 0\n\n[INFO] ------------------------------------------------------------------------\n[INFO] BUILD SUCCESS\n[INFO] ------------------------------------------------------------------------\n[INFO] Total time: 01:09 min\n[INFO] Finished at: 2019-08-04T05:25:12-05:00\n[INFO] ------------------------------------------------------------------------\n\nC:\\MaryZheng\\Workspaces\\jdk12\\java-collections-demo><\/pre>\n
5.4 Stack_StringTest<\/h3>\n
Stack<\/a> extends from Vector and implements List<\/a> interface. It models the Stack data structure<\/a>.<\/p>\n
In this step, I will create a
Stack_StringTest<\/code> class which extends fromListBase_StringTest<\/code>. <\/p>\nIn the
setup_colItems_with_4_items<\/code> method, it will create aStack<\/code> instance and add four items. This method is also annotated with@Before<\/code> annotation so it will be called for each test method.<\/p>\nIn the
Stack_push_pop method<\/code>, it will push an element and pop an element based on first-in-last-out order.<\/p>\nStack_StringTest.java<\/em><\/span>\n<\/p>\n
package jcg.zheng.demo;\n\nimport static org.junit.Assert.assertEquals;\nimport static org.junit.Assert.assertTrue;\n\nimport java.util.Stack;\n\nimport org.junit.Before;\nimport org.junit.Test;\nimport org.slf4j.LoggerFactory;\n\npublic class Stack_StringTest extends ListBase_StringTest {\n\n @Before\n public void setup_colItems_with_4_items() {\n logger = LoggerFactory.getLogger(this.getClass());\n\n colItems = new Stack<String>();\n assertTrue(colItems.isEmpty());\n\n colItems.add(\"Item1\");\n assertEquals(1, colItems.size());\n colItems.add(\"Item2\");\n assertEquals(2, colItems.size());\n colItems.add(\"Item3\");\n assertEquals(3, colItems.size());\n colItems.add(\"Item4\");\n assertEquals(4, colItems.size());\n\n listItems = new Stack<String>();\n listItems.addAll(colItems);\n assertEquals(4, listItems.size());\n listItems.clear();\n }\n\n @Test\n public void Stack_push_pop() {\n ((Stack<String>) listItems).push(\"Mary\");\n String item = ((Stack<String>) listItems).pop();\n assertEquals(\"Mary\", item);\n }\n\n}\n<\/pre>\nExecute
mvn test -Dtest=Stack_StringTest<\/code><\/p>\nOutput<\/em><\/span>\n<\/p>\n
-------------------------------------------------------\n T E S T S\n-------------------------------------------------------\nRunning jcg.zheng.demo.Stack_StringTest\n05:26:53.868 [main] INFO jcg.zheng.demo.Stack_StringTest - Retrieving items with loop using index and size list\n05:26:53.933 [main] INFO jcg.zheng.demo.Stack_StringTest - Index: 0 - Item: Tom\n05:26:53.934 [main] INFO jcg.zheng.demo.Stack_StringTest - Index: 1 - Item: Mary\n05:26:53.935 [main] INFO jcg.zheng.demo.Stack_StringTest - Index: 2 - Item: Shan\n05:26:53.936 [main] INFO jcg.zheng.demo.Stack_StringTest - Index: 3 - Item: Zheng\n05:26:53.939 [main] INFO jcg.zheng.demo.Stack_StringTest - Sorted List\n05:26:53.940 [main] INFO jcg.zheng.demo.Stack_StringTest - Index: 0 - Item: Mary\n05:26:53.942 [main] INFO jcg.zheng.demo.Stack_StringTest - Index: 1 - Item: Shan\n05:26:53.943 [main] INFO jcg.zheng.demo.Stack_StringTest - Index: 2 - Item: Tom\n05:26:53.943 [main] INFO jcg.zheng.demo.Stack_StringTest - Index: 3 - Item: Zheng\n05:26:53.973 [main] INFO jcg.zheng.demo.Stack_StringTest - The arraycolItems contains the following elements: [Item1, Item2, Item3, Item4, new Item]\n05:26:53.975 [main] INFO jcg.zheng.demo.Stack_StringTest - Retrieving items using for loop\n05:26:53.977 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item1\n05:26:53.978 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item2\n05:26:53.978 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item3\n05:26:53.978 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item4\n05:26:53.981 [main] INFO jcg.zheng.demo.Stack_StringTest - Retrieving items using Java 8 Stream\n05:26:53.984 [main] INFO jcg.zheng.demo.Stack_StringTest - Item1\n05:26:53.984 [main] INFO jcg.zheng.demo.Stack_StringTest - Item2\n05:26:53.984 [main] INFO jcg.zheng.demo.Stack_StringTest - Item3\n05:26:53.984 [main] INFO jcg.zheng.demo.Stack_StringTest - Item4\n05:26:53.985 [main] INFO jcg.zheng.demo.Stack_StringTest - Retrieving items using iterator\n05:26:53.986 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item1\n05:26:53.986 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item2\n05:26:53.986 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item3\n05:26:53.986 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item4\n05:26:53.987 [main] INFO jcg.zheng.demo.Stack_StringTest - Retrieving items using iterator\n05:26:53.988 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item1\n05:26:53.988 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item2\n05:26:53.988 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item3\n05:26:53.988 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item4\n05:26:53.994 [main] INFO jcg.zheng.demo.Stack_StringTest - Removing items using iterator\n05:26:53.995 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item1\n05:26:53.996 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item2\n05:26:53.996 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item3\n05:26:53.996 [main] INFO jcg.zheng.demo.Stack_StringTest - Item is: Item4\n05:26:53.997 [main] INFO jcg.zheng.demo.Stack_StringTest - The array created after the conversion of our arraycolItems is: [Item1, Item2, Item3, Item4]\n05:26:53.999 [main] INFO jcg.zheng.demo.Stack_StringTest - default toArray(intfunction):[Item1, Item2, Item3, Item4]\nTests run: 18, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.616 sec\n\nResults :\n\nTests run: 18, Failures: 0, Errors: 0, Skipped: 0\n\n[INFO] ------------------------------------------------------------------------\n[INFO] BUILD SUCCESS\n[INFO] ------------------------------------------------------------------------\n[INFO] Total time: 10.761 s\n[INFO] Finished at: 2019-08-04T05:26:54-05:00\n[INFO] ------------------------------------------------------------------------\n\nC:\\MaryZheng\\Workspaces\\jdk12\\java-collections-demo><\/pre>\n
5.5 ArrayList_POJOTest<\/h3>\n
In this step, I will create an
ArrayList_POJOTest<\/code> class which extends fromCollectionBase_POJOTest<\/code>. <\/p>\nIn the
setup_list_with_4_items<\/code> method, it will create anArrayList<\/code> instance and add four items. This method is also annotated with@Before<\/code> annotation so it will be called for each test method.<\/p>\nArrayList_POJOTest.java<\/em><\/span>\n<\/p>\n
package jcg.zheng.demo;\n\nimport static org.junit.Assert.assertEquals;\nimport static org.junit.Assert.assertTrue;\n\nimport java.util.ArrayList;\n\nimport org.junit.Before;\nimport org.slf4j.LoggerFactory;\n\nimport jcg.zheng.demo.data.SomeData;\n\npublic class ArrayList_POJOTest extends CollectionBase_POJOTest {\n\n\t@Before\n\tpublic void setup_list_with_4_items() {\n\t\tlogger = LoggerFactory.getLogger(this.getClass());\n\n\t\tlist = new ArrayList<SomeData>();\n\t\tassertTrue(list.isEmpty());\n\n\t\tlist.add(buildSomeData(1, \"Item1\"));\n\t\tassertEquals(1, list.size());\n\t\tlist.add(buildSomeData(2, \"Item2\"));\n\t\tassertEquals(2, list.size());\n\t\tlist.add(buildSomeData(3, \"Item3\"));\n\t\tassertEquals(3, list.size());\n\t\tlist.add(buildSomeData(4, \"Item4\"));\n\t\tassertEquals(4, list.size());\n\t}\n\n}\n<\/pre>\nExecute
mvn test -Dtest=ArrayList_POJOTest<\/code><\/p>\nOutput<\/em><\/span>\n<\/p>\n
-------------------------------------------------------\n T E S T S\n-------------------------------------------------------\nRunning jcg.zheng.demo.ArrayList_POJOTest\n05:28:57.110 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - The arraylist contains the following elements: [SomeData [name=Item1, id=1], SomeData [name=Item2, id=2], SomeData [name=Item3, id=3], SomeData [name=Item4, id=4], SomeData [name=test, id=1]]\n05:28:57.127 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Retrieving items using for loop\n05:28:57.129 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Item is: SomeData [name=Item1, id=1]\n05:28:57.130 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Item is: SomeData [name=Item2, id=2]\n05:28:57.130 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Item is: SomeData [name=Item3, id=3]\n05:28:57.131 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Item is: SomeData [name=Item4, id=4]\n05:28:57.133 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Retrieving items using Java 8 Stream\n05:28:57.138 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - SomeData [name=Item1, id=1]\n05:28:57.139 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - SomeData [name=Item2, id=2]\n05:28:57.140 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - SomeData [name=Item3, id=3]\n05:28:57.140 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - SomeData [name=Item4, id=4]\n05:28:57.143 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Retrieving items using iterator\n05:28:57.145 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Item is: SomeData [name=Item1, id=1]\n05:28:57.145 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Item is: SomeData [name=Item2, id=2]\n05:28:57.145 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Item is: SomeData [name=Item3, id=3]\n05:28:57.145 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Item is: SomeData [name=Item4, id=4]\n05:28:57.147 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Retrieving items using iterator\n05:28:57.148 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Item is: SomeData [name=Item1, id=1]\n05:28:57.148 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Item is: SomeData [name=Item2, id=2]\n05:28:57.149 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Item is: SomeData [name=Item3, id=3]\n05:28:57.149 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - Item is: SomeData [name=Item4, id=4]\n05:28:57.157 [main] INFO jcg.zheng.demo.ArrayList_POJOTest - The array created after the conversion of our arraylist is: [SomeData [name=Item1, id=1], SomeData [name=Item2, id=2], SomeData [name=Item3, id=3], SomeData [name=Item4, id=4]]\nTests run: 10, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.473 sec\n\nResults :\n\nTests run: 10, Failures: 0, Errors: 0, Skipped: 0\n\n[INFO] ------------------------------------------------------------------------\n[INFO] BUILD SUCCESS\n[INFO] ------------------------------------------------------------------------\n[INFO] Total time: 10.397 s\n[INFO] Finished at: 2019-08-04T05:28:57-05:00\n[INFO] ------------------------------------------------------------------------\n\nC:\\MaryZheng\\Workspaces\\jdk12\\java-collections-demo><\/pre>\n
5.6 HashSet_POJOTest<\/h3>\n
- Added more interfaces and classes at version 6<\/a>, including