Containers in Depth: Exercise 22 - simple implementation

kean0212 · May 17, 2017 · 097b0a2 · 097b0a2
1 parent 94ac641
commit 097b0a2
Show file tree

Hide file tree

Showing 2 changed files with 38 additions and 0 deletions.
diff --git a/ContainersInDepth/SimpleHashMap.java b/ContainersInDepth/SimpleHashMap.java
@@ -4,6 +4,7 @@
 import java.util.Set;
 import java.util.HashSet;
 import java.util.ListIterator;
+import java.util.Iterator;
 
 public class SimpleHashMap<K, V> extends AbstractMap<K, V> {
     static final int SIZE = 997;
@@ -88,4 +89,30 @@ public void putAll(Map<? extends K, ? extends V> map) {
             put((K) mapEntry.getKey(), (V) mapEntry.getValue());
         }
     }
+
+    public void clear() {
+        for (LinkedList<Map.Entry<K, V>> bucket : buckets) {
+            if (bucket != null) {
+                bucket.clear();
+            }
+        }
+    }
+
+    @SuppressWarnings("unchecked")
+    public V remove(Object key) {
+        V oldValue = null;
+        int bucketIndex = Math.abs(key.hashCode()) % SIZE;
+        LinkedList<Map.Entry<K, V>> bucket = buckets[bucketIndex];
+        if (bucket != null) {
+            Iterator iterator = bucket.iterator();
+            while (iterator.hasNext()) {
+                Map.Entry<K, V> entry = (Map.Entry<K, V>) iterator.next();
+                if (key != null && key.equals(entry.getKey())) {
+                    oldValue = entry.getValue();
+                    iterator.remove();
+                }
+            }
+        }
+        return oldValue;
+    }
 }
diff --git a/ContainersInDepth/SimpleHashMapDemo.java b/ContainersInDepth/SimpleHashMapDemo.java
@@ -12,5 +12,16 @@ public static void main(String[] args) {
         Util.println("size of collisions: " + simpleHashMap.size());
         Util.println("number of collisions: " + simpleHashMap.getNumberOfCollisions()); // size
         Util.println("number of probes: " + simpleHashMap.getNumberOfProbes()); // size
+
+        simpleHashMap.clear();
+        Util.println("after clear(): " + simpleHashMap);
+
+        simpleHashMap.putAll(capitals);
+
+        Util.println("simpleHashMap.remove(\"CAPE VERDE\"): " + simpleHashMap.remove("CAPE VERDE"));
+        Util.println(simpleHashMap);
+
+        Util.println("simpleHashMap.remove(\"hahaha\"): " + simpleHashMap.remove("hahaha"));
+        Util.println(simpleHashMap);
     }
 }