sketch a few more classpath classes

classpath/java/util/WeakHashMap.java

@@ -0,0 +1,95 @@
+package java.util;
+
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.Reference;
+import java.lang.ref.WeakReference;
+
+public class WeakHashMap<K, V> implements Map<K, V> {
+  private final HashMap<K, V> map;
+  private final ReferenceQueue queue;
+
+  public WeakHashMap(int capacity) {
+    map = new HashMap(capacity, new MyCellFactory());
+    queue = new ReferenceQueue();
+  }
+
+  public WeakHashMap() {
+    this(0);
+  }
+
+  private void poll() {
+    for (MyCell<K, V> c = (MyCell<K, V>) queue.poll();
+         c != null;
+         c = (MyCell<K, V>) queue.poll())
+    {
+      map.remove(c);
+    }
+  }
+
+  public int size() {
+    return map.size();
+  }
+
+  public V get(K key) {
+    poll();
+    return map.get(key);
+  }
+
+  public V put(K key, V value) {
+    poll();
+    return map.put(key, value);
+  }
+
+  public V remove(K key) {
+    poll();
+    return map.remove(key);
+  }
+
+  private static class MyCell<K, V>
+    extends WeakReference<K>
+    implements HashMap.Cell<K, V>
+  {
+    public V value;
+    public HashMap.Cell<K, V> next;
+    public int hashCode;
+
+    public MyCell(K key, V value, HashMap.Cell<K, V> next) {
+      super(key);
+      this.value = value;
+      this.next = next;
+      this.hashCode = key.hashCode();
+    }
+
+    public K getKey() {
+      return get();
+    }
+
+    public V getValue() {
+      return value;
+    }
+
+    public void setValue(V value) {
+      this.value = value;
+    }
+
+    public HashMap.Cell<K, V> next() {
+      return next;
+    }
+
+    public void setNext(HashMap.Cell<K, V> next) {
+      this.next = next;
+    }
+
+    public int hashCode() {
+      return hashCode;
+    }
+  }
+
+  private static class MyCellFactory<K, V>
+    implements HashMap.CellFactory<K, V>
+  {
+    public HashMap.Cell<K, V> make(K key, V value, HashMap.Cell<K, V> next) {
+      return new MyCell(key, value, next);
+    }
+  }
+}