From 3b6d709108d17b3a206d1de49f39279bfc9324b8 Mon Sep 17 00:00:00 2001 From: Egima profile Date: Wed, 21 Dec 2016 23:07:46 +0300 Subject: [PATCH] Code for Map (#909) * made changes to java reflection * removed redundant method makeSound in Animal abstract class * added project for play-framework article * added project for regex * changed regex project from own model to core-java * added project for routing in play * made changes to regex project * refactored code for REST API with Play project * refactored student store indexing to zero base * added unit tests, removed bad names * added NIO Selector project under core-java module * requested changes made * added project for nio2 * standardized exception based tests * fixed exception based tests * removed redundant files * added network interface project * used UUID other than timestamps * fixed network interface tests * removed filetest change * made changes to NIO2 FileTest names * added project for asyncronous channel apis * added project for NIO2 advanced filesystems APIS * merge conflicts * merged changes to asyncfiletest with future get API * removed while loops from async client and server * added project for java8 optional * fixed merge conflicts in spring-core * fixed optional * fixed optional * fixed asyncechotest * shifted optional to own package * made additional tests to demo filter API * added code for Map --- .../java/com/baeldung/java/map/MyKey.java | 59 +++ .../baeldung/java/map/MyLinkedHashMap.java | 25 ++ .../java/com/baeldung/java/map/MapTest.java | 350 ++++++++++++++++++ 3 files changed, 434 insertions(+) create mode 100644 core-java/src/main/java/com/baeldung/java/map/MyKey.java create mode 100644 core-java/src/main/java/com/baeldung/java/map/MyLinkedHashMap.java create mode 100644 core-java/src/test/java/com/baeldung/java/map/MapTest.java diff --git a/core-java/src/main/java/com/baeldung/java/map/MyKey.java b/core-java/src/main/java/com/baeldung/java/map/MyKey.java new file mode 100644 index 0000000000..a2587c1dc1 --- /dev/null +++ b/core-java/src/main/java/com/baeldung/java/map/MyKey.java @@ -0,0 +1,59 @@ +package com.baeldung.java.map; + +public class MyKey { + private String name; + private int id; + + public MyKey(int id, String name) { + this.id = id; + this.name = name; + } + + public String getName() { + return name; + } + + public void setName(String name) { + this.name = name; + } + + public int getId() { + return id; + } + + public void setId(int id) { + this.id = id; + } + + @Override + public int hashCode() { + System.out.println("Calling hashCode()"); + return id; + } + + @Override + public String toString() { + return "MyKey [name=" + name + ", id=" + id + "]"; + } + + @Override + public boolean equals(Object obj) { + System.out.println("Calling equals() for key: " + obj); + if (this == obj) + return true; + if (obj == null) + return false; + if (getClass() != obj.getClass()) + return false; + MyKey other = (MyKey) obj; + if (id != other.id) + return false; + if (name == null) { + if (other.name != null) + return false; + } else if (!name.equals(other.name)) + return false; + return true; + } + +} diff --git a/core-java/src/main/java/com/baeldung/java/map/MyLinkedHashMap.java b/core-java/src/main/java/com/baeldung/java/map/MyLinkedHashMap.java new file mode 100644 index 0000000000..e1c0071ed3 --- /dev/null +++ b/core-java/src/main/java/com/baeldung/java/map/MyLinkedHashMap.java @@ -0,0 +1,25 @@ +package com.baeldung.java.map; + +import java.util.LinkedHashMap; +import java.util.Map; + +public class MyLinkedHashMap extends LinkedHashMap { + + /** + * + */ + private static final long serialVersionUID = 1L; + private static final int MAX_ENTRIES = 5; + + + public MyLinkedHashMap(int initialCapacity, float loadFactor, boolean accessOrder) { + super(initialCapacity, loadFactor, accessOrder); + } + + + @Override + protected boolean removeEldestEntry(Map.Entry eldest) { + return size() > MAX_ENTRIES; + } + +} diff --git a/core-java/src/test/java/com/baeldung/java/map/MapTest.java b/core-java/src/test/java/com/baeldung/java/map/MapTest.java new file mode 100644 index 0000000000..a348869a5c --- /dev/null +++ b/core-java/src/test/java/com/baeldung/java/map/MapTest.java @@ -0,0 +1,350 @@ +package com.baeldung.java.map; + +import static org.junit.Assert.assertEquals; +import static org.junit.Assert.assertFalse; +import static org.junit.Assert.assertNull; +import static org.junit.Assert.assertTrue; + +import java.util.Collection; +import java.util.Comparator; +import java.util.ConcurrentModificationException; +import java.util.HashMap; +import java.util.Iterator; +import java.util.LinkedHashMap; +import java.util.Map; +import java.util.Map.Entry; +import java.util.Set; +import java.util.TreeMap; + +import org.junit.Test; + +public class MapTest { + @Test + public void givenHashMap_whenRetrievesKeyset_thenCorrect() { + Map map = new HashMap<>(); + map.put("name", "baeldung"); + map.put("type", "blog"); + + Set keys = map.keySet(); + + assertEquals(2, keys.size()); + assertTrue(keys.contains("name")); + assertTrue(keys.contains("type")); + } + + @Test + public void givenHashMap_whenRetrievesValues_thenCorrect() { + Map map = new HashMap<>(); + map.put("name", "baeldung"); + map.put("type", "blog"); + + Collection values = map.values(); + + assertEquals(2, values.size()); + assertTrue(values.contains("baeldung")); + assertTrue(values.contains("blog")); + } + + @Test + public void givenHashMap_whenRetrievesEntries_thenCorrect() { + Map map = new HashMap<>(); + map.put("name", "baeldung"); + map.put("type", "blog"); + + Set> entries = map.entrySet(); + + assertEquals(2, entries.size()); + for (Entry e : entries) { + String key = e.getKey(); + String val = e.getValue(); + assertTrue(key.equals("name") || key.equals("type")); + assertTrue(val.equals("baeldung") || val.equals("blog")); + } + } + + @Test + public void givenKeySet_whenChangeReflectsInMap_thenCorrect() { + Map map = new HashMap<>(); + map.put("name", "baeldung"); + map.put("type", "blog"); + + assertEquals(2, map.size()); + + Set keys = map.keySet(); + + keys.remove("name"); + assertEquals(1, map.size()); + } + + @Test(expected = ConcurrentModificationException.class) + public void givenIterator_whenFailsFastOnModification_thenCorrect() { + Map map = new HashMap<>(); + map.put("name", "baeldung"); + map.put("type", "blog"); + + Set keys = map.keySet(); + Iterator it = keys.iterator(); + map.remove("type"); + while (it.hasNext()) { + String key = it.next(); + } + } + + public void givenIterator_whenRemoveWorks_thenCorrect() { + Map map = new HashMap<>(); + map.put("name", "baeldung"); + map.put("type", "blog"); + + Set keys = map.keySet(); + Iterator it = keys.iterator(); + while (it.hasNext()) { + it.next(); + it.remove(); + } + assertEquals(0, map.size()); + } + + @Test + public void whenHashCodeIsCalledOnPut_thenCorrect() { + MyKey key = new MyKey(1, "name"); + Map map = new HashMap<>(); + map.put(key, "val"); + } + + @Test + public void whenHashCodeIsCalledOnGet_thenCorrect() { + MyKey key = new MyKey(1, "name"); + Map map = new HashMap<>(); + map.put(key, "val"); + map.get(key); + } + + @Test + public void whenGetWorks_thenCorrect() { + Map map = new HashMap<>(); + map.put("key", "val"); + + String val = map.get("key"); + + assertEquals("val", val); + } + + @Test + public void givenNewKey_whenPutReturnsNull_thenCorrect() { + Map map = new HashMap<>(); + + String rtnVal = map.put("key1", "val1"); + + assertNull(rtnVal); + } + + @Test + public void givenUnmappedKey_whenGetReturnsNull_thenCorrect() { + Map map = new HashMap<>(); + + String rtnVal = map.get("key1"); + + assertNull(rtnVal); + } + + @Test + public void givenNullVal_whenPutReturnsNull_thenCorrect() { + Map map = new HashMap<>(); + + String rtnVal = map.put("key1", null); + + assertNull(rtnVal); + } + + @Test + public void givenNullKeyAndVal_whenAccepts_thenCorrect() { + Map map = new HashMap<>(); + + map.put(null, null); + } + + @Test + public void givenNullVal_whenRetrieves_thenCorrect() { + Map map = new HashMap<>(); + map.put("key", null); + + String val = map.get("key"); + + assertNull(val); + } + + @Test + public void whenContainsDistinguishesNullValues_thenCorrect() { + Map map = new HashMap<>(); + + String val1 = map.get("key"); + boolean valPresent = map.containsKey("key"); + + assertNull(val1); + assertFalse(valPresent); + + map.put("key", null); + String val = map.get("key"); + valPresent = map.containsKey("key"); + + assertNull(val); + assertTrue(valPresent); + + } + + @Test + public void whenPutReturnsPrevValue_thenCorrect() { + Map map = new HashMap<>(); + map.put("key1", "val1"); + String rtnVal = map.put("key1", "val2"); + + assertEquals("val1", rtnVal); + } + + + + @Test + public void whenCallsEqualsOnCollision_thenCorrect() { + HashMap map = new HashMap<>(); + MyKey k1 = new MyKey(1, "firstKey"); + MyKey k2 = new MyKey(2, "secondKey"); + MyKey k3 = new MyKey(2, "thirdKey"); + + System.out.println("storing value for k1"); + map.put(k1, "firstValue"); + + System.out.println("storing value for k2"); + map.put(k2, "secondValue"); + + System.out.println("storing value for k3"); + map.put(k3, "thirdValue"); + + System.out.println("retrieving value for k1"); + String v1 = map.get(k1); + + System.out.println("retrieving value for k2"); + String v2 = map.get(k2); + + System.out.println("retrieving value for k3"); + String v3 = map.get(k3); + + assertEquals("firstValue", v1); + assertEquals("secondValue", v2); + assertEquals("thirdValue", v3); + + } + + @Test + public void givenLinkedHashMap_whenGetsOrderedKeyset_thenCorrect() { + LinkedHashMap map = new LinkedHashMap<>(); + map.put(1, null); + map.put(2, null); + map.put(3, null); + map.put(4, null); + map.put(5, null); + Set keys = map.keySet(); + Integer[] arr = keys.toArray(new Integer[0]); + for (int i = 0; i < arr.length; i++) { + assertEquals(new Integer(i + 1), arr[i]); + + } + } + + @Test + public void givenLinkedHashMap_whenAccessOrderWorks_thenCorrect() { + LinkedHashMap map = new LinkedHashMap<>(16, .75f, true); + map.put(1, null); + map.put(2, null); + map.put(3, null); + map.put(4, null); + map.put(5, null); + Set keys = map.keySet(); + assertEquals("[1, 2, 3, 4, 5]", keys.toString()); + map.get(4); + assertEquals("[1, 2, 3, 5, 4]", keys.toString()); + map.get(1); + assertEquals("[2, 3, 5, 4, 1]", keys.toString()); + map.get(3); + assertEquals("[2, 5, 4, 1, 3]", keys.toString()); + } + + @Test + public void givenLinkedHashMap_whenRemovesEldestEntry_thenCorrect() { + LinkedHashMap map = new MyLinkedHashMap<>(16, .75f, true); + map.put(1, null); + map.put(2, null); + map.put(3, null); + map.put(4, null); + map.put(5, null); + Set keys = map.keySet(); + assertEquals("[1, 2, 3, 4, 5]", keys.toString()); + map.put(6, null); + assertEquals("[2, 3, 4, 5, 6]", keys.toString()); + map.put(7, null); + assertEquals("[3, 4, 5, 6, 7]", keys.toString()); + map.put(8, null); + assertEquals("[4, 5, 6, 7, 8]", keys.toString()); + } + + @Test + public void givenTreeMap_whenOrdersEntriesNaturally_thenCorrect() { + TreeMap map = new TreeMap<>(); + map.put(3, "val"); + map.put(2, "val"); + map.put(1, "val"); + map.put(5, "val"); + map.put(4, "val"); + assertEquals("[1, 2, 3, 4, 5]", map.keySet().toString()); + } + + @Test + public void givenTreeMap_whenOrdersEntriesNaturally_thenCorrect2() { + TreeMap map = new TreeMap<>(); + map.put("c", "val"); + map.put("b", "val"); + map.put("a", "val"); + map.put("e", "val"); + map.put("d", "val"); + + assertEquals("[a, b, c, d, e]", map.keySet().toString()); + } + + @Test + public void givenTreeMap_whenOrdersEntriesByComparator_thenCorrect() { + TreeMap map = new TreeMap<>(new Comparator() { + + @Override + public int compare(Integer o1, Integer o2) { + return o2 - o1; + } + }); + map.put(3, "val"); + map.put(2, "val"); + map.put(1, "val"); + map.put(5, "val"); + map.put(4, "val"); + + assertEquals("[5, 4, 3, 2, 1]", map.keySet().toString()); + } + + @Test + public void givenTreeMap_whenPerformsQueries_thenCorrect() { + TreeMap map = new TreeMap<>(); + map.put(3, "val"); + map.put(2, "val"); + map.put(1, "val"); + map.put(5, "val"); + map.put(4, "val"); + + Integer highestKey = map.lastKey(); + Integer lowestKey = map.firstKey(); + Set keysLessThan3 = map.headMap(3).keySet(); + Set keysGreaterThanEqTo3 = map.tailMap(3).keySet(); + + assertEquals(new Integer(5), highestKey); + assertEquals(new Integer(1), lowestKey); + assertEquals("[1, 2]", keysLessThan3.toString()); + assertEquals("[3, 4, 5]", keysGreaterThanEqTo3.toString()); + } + +}