Solution

src/main/java/core/basesyntax/Application.java

@@ -0,0 +1,18 @@
+package core.basesyntax;
+
+import core.basesyntax.impl.StorageImpl;
+
+public class Application {
+    public static void main(String[] args) {
+        Storage<Integer, String> storage = new StorageImpl<>();
+        storage.put(1, "Value1");
+        storage.put(2, "Value2");
+        storage.put(3, "Value3");
+
+        System.out.println("Get value by key 2: " + storage.get(2));
+        System.out.println("Storage size: " + storage.size());
+
+        storage.put(1, "NewValue1");
+        System.out.println("Get updated value by key 1: " + storage.get(1));
+    }
+}

src/main/java/core/basesyntax/StorageImpl.java

@@ -0,0 +1,43 @@
+package core.basesyntax;
+
+public class StorageImpl<K, V> implements Storage<K, V> {
+    private static final int MAX_SIZE = 10;
+    private final K[] keys;
+    private final V[] values;
+    private int size;
+
+    public StorageImpl() {
+        keys = (K[]) new Object[MAX_SIZE];
+        values = (V[]) new Object[MAX_SIZE];
+    }
+
+    @Override
+    public void put(K key, V value) {
+        for (int i = 0; i < size; i++) {
+            if (key == null && keys[i] == null || key != null && key.equals(keys[i])) {
+                values[i] = value;
+                return;
+            }
+        }
+        if (size < MAX_SIZE) {
+            keys[size] = key;
+            values[size] = value;
+            size++;
+        }
+    }
+
+    @Override
+    public V get(K key) {
+        for (int i = 0; i < size; i++) {
+            if (key == null && keys[i] == null || key != null && key.equals(keys[i])) {
+                return values[i];
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public int size() {
+        return size;
+    }
+}

src/main/java/core/basesyntax/impl/StorageImpl.java

@@ -3,17 +3,44 @@
 import core.basesyntax.Storage;
 
 public class StorageImpl<K, V> implements Storage<K, V> {
+    private static final int MAX_SIZE = 10;
+    private final K[] keys;
+    private final V[] values;
+    private int size;
+
+    @SuppressWarnings("unchecked")
+    public StorageImpl() {
+        keys = (K[]) new Object[MAX_SIZE];
+        values = (V[]) new Object[MAX_SIZE];
+    }
+
     @Override
     public void put(K key, V value) {
+        for (int i = 0; i < size; i++) {
+            if (key == keys[i] || (key != null && key.equals(keys[i]))) {
+                values[i] = value;
+                return;
+            }
+        }
+        if (size < MAX_SIZE) {
+            keys[size] = key;
+            values[size] = value;
+            size++;
+        }
     }
 
     @Override
     public V get(K key) {
+        for (int i = 0; i < size; i++) {
+            if (key == keys[i] || (key != null && key.equals(keys[i]))) {
+                return values[i];
+            }
+        }
         return null;
     }
 
     @Override
     public int size() {
-        return -1;
+        return size;
     }
 }