BAEL-5686: Implementing a Map with Multiple Keys (#12531)

core-java-modules/core-java-collections-maps-5/src/main/java/com/baeldung/map/multikey/BaseClassUserCache.java

@@ -0,0 +1,24 @@
+package com.baeldung.map.multikey;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class BaseClassUserCache {
+    private final Map<Object, User> cache = new HashMap<>();
+
+    public User getById(String id) {
+        return cache.get(id);
+    }
+
+    public User getById(Long id) {
+        return cache.get(id);
+    }
+
+    public void storeById(String id, User user) {
+        cache.put(id, user);
+    }
+
+    public void storeById(Long id, User user) {
+        cache.put(id, user);
+    }
+}

core-java-modules/core-java-collections-maps-5/src/main/java/com/baeldung/map/multikey/MultipleMapsUserCache.java

@@ -0,0 +1,25 @@
+package com.baeldung.map.multikey;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class MultipleMapsUserCache {
+    private final Map<String, User> stringCache = new HashMap<>();
+    private final Map<Long, User> longCache = new HashMap<>();
+
+    public User getById(String id) {
+        return stringCache.get(id);
+    }
+
+    public User getById(Long id) {
+        return longCache.get(id);
+    }
+
+    public void storeById(String id, User user) {
+        stringCache.put(id, user);
+    }
+
+    public void storeById(Long id, User user) {
+        longCache.put(id, user);
+    }
+}

core-java-modules/core-java-collections-maps-5/src/main/java/com/baeldung/map/multikey/User.java

@@ -0,0 +1,13 @@
+package com.baeldung.map.multikey;
+
+public class User {
+    private final String name;
+
+    public User(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+}

core-java-modules/core-java-collections-maps-5/src/main/java/com/baeldung/map/multikey/WrapperClassUserCache.java

@@ -0,0 +1,42 @@
+package com.baeldung.map.multikey;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+
+public class WrapperClassUserCache {
+    private Map<CacheKey, User> cache = new HashMap<>();
+
+    public User getById(CacheKey key) {
+        return cache.get(key);
+    }
+
+    public void storeById(CacheKey key, User user) {
+        cache.put(key, user);
+    }
+
+    public static class CacheKey {
+        private final Object value;
+
+        public CacheKey(String value) {
+            this.value = value;
+        }
+
+        public CacheKey(Long value) {
+            this.value = value;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            CacheKey cacheKey = (CacheKey) o;
+            return value.equals(cacheKey.value);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(value);
+        }
+    }
+}

core-java-modules/core-java-collections-maps-5/src/main/java/com/baeldung/map/multikey/WrapperInterfaceUserCache.java

@@ -0,0 +1,62 @@
+package com.baeldung.map.multikey;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+
+public class WrapperInterfaceUserCache {
+    private Map<CacheKey, User> cache = new HashMap<>();
+
+    public User getById(CacheKey key) {
+        return cache.get(key);
+    }
+
+    public void storeById(CacheKey key, User user) {
+        cache.put(key, user);
+    }
+
+    public interface CacheKey {
+    }
+
+    public static class StringCacheKey implements CacheKey{
+        private final String value;
+
+        public StringCacheKey(String value) {
+            this.value = value;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            StringCacheKey that = (StringCacheKey) o;
+            return value.equals(that.value);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(value);
+        }
+    }
+
+    public static class LongCacheKey implements CacheKey {
+        private final Long value;
+
+        public LongCacheKey(Long value) {
+            this.value = value;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            LongCacheKey that = (LongCacheKey) o;
+            return value.equals(that.value);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(value);
+        }
+    }
+}

core-java-modules/core-java-collections-maps-5/src/test/java/com/baeldung/map/multikey/BaseClassUserCacheUnitTest.java

@@ -0,0 +1,32 @@
+package com.baeldung.map.multikey;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class BaseClassUserCacheUnitTest {
+    private BaseClassUserCache cache = new BaseClassUserCache();
+
+    @BeforeEach
+    public void setup() {
+        cache.storeById("a", new User("User A"));
+        cache.storeById("b", new User("User B"));
+        cache.storeById(3L, new User("User 3"));
+        cache.storeById(4L, new User("User 4"));
+    }
+
+    @Test
+    public void getByString() {
+        User user = cache.getById("b");
+        assertNotNull(user);
+        assertEquals("User B", user.getName());
+    }
+
+    @Test
+    public void getByLong() {
+        User user = cache.getById(4L);
+        assertNotNull(user);
+        assertEquals("User 4", user.getName());
+    }
+}

core-java-modules/core-java-collections-maps-5/src/test/java/com/baeldung/map/multikey/MultipleMapsUserCacheUnitTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.map.multikey;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+class MultipleMapsUserCacheUnitTest {
+    private MultipleMapsUserCache cache = new MultipleMapsUserCache();
+
+    @BeforeEach
+    public void setup() {
+        cache.storeById("a", new User("User A"));
+        cache.storeById("b", new User("User B"));
+        cache.storeById(3L, new User("User 3"));
+        cache.storeById(4L, new User("User 4"));
+    }
+
+    @Test
+    public void getByString() {
+        User user = cache.getById("b");
+        assertNotNull(user);
+        assertEquals("User B", user.getName());
+    }
+
+    @Test
+    public void getByLong() {
+        User user = cache.getById(4L);
+        assertNotNull(user);
+        assertEquals("User 4", user.getName());
+    }
+}

core-java-modules/core-java-collections-maps-5/src/test/java/com/baeldung/map/multikey/WrapperClassUserCacheUnitTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.map.multikey;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+class WrapperClassUserCacheUnitTest {
+    private WrapperClassUserCache cache = new WrapperClassUserCache();
+
+    @BeforeEach
+    public void setup() {
+        cache.storeById(new WrapperClassUserCache.CacheKey("a"), new User("User A"));
+        cache.storeById(new WrapperClassUserCache.CacheKey("b"), new User("User B"));
+        cache.storeById(new WrapperClassUserCache.CacheKey(3L), new User("User 3"));
+        cache.storeById(new WrapperClassUserCache.CacheKey(4L), new User("User 4"));
+    }
+
+    @Test
+    public void getByString() {
+        User user = cache.getById(new WrapperClassUserCache.CacheKey("b"));
+        assertNotNull(user);
+        assertEquals("User B", user.getName());
+    }
+
+    @Test
+    public void getByLong() {
+        User user = cache.getById(new WrapperClassUserCache.CacheKey(4L));
+        assertNotNull(user);
+        assertEquals("User 4", user.getName());
+    }
+}

core-java-modules/core-java-collections-maps-5/src/test/java/com/baeldung/map/multikey/WrapperInterfaceUserCacheUnitTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.map.multikey;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+class WrapperInterfaceUserCacheUnitTest {
+    private WrapperInterfaceUserCache cache = new WrapperInterfaceUserCache();
+
+    @BeforeEach
+    public void setup() {
+        cache.storeById(new WrapperInterfaceUserCache.StringCacheKey("a"), new User("User A"));
+        cache.storeById(new WrapperInterfaceUserCache.StringCacheKey("b"), new User("User B"));
+        cache.storeById(new WrapperInterfaceUserCache.LongCacheKey(3L), new User("User 3"));
+        cache.storeById(new WrapperInterfaceUserCache.LongCacheKey(4L), new User("User 4"));
+    }
+
+    @Test
+    public void getByString() {
+        User user = cache.getById(new WrapperInterfaceUserCache.StringCacheKey("b"));
+        assertNotNull(user);
+        assertEquals("User B", user.getName());
+    }
+
+    @Test
+    public void getByLong() {
+        User user = cache.getById(new WrapperInterfaceUserCache.LongCacheKey(4L));
+        assertNotNull(user);
+        assertEquals("User 4", user.getName());
+    }
+}