X-Git-Url: http://source.jalview.org/gitweb/?a=blobdiff_plain;ds=sidebyside;f=src%2Fjalview%2Futil%2FLinkedIdentityHashSet.java;h=bce540fee65364fff058eaf5fd039d506f907ace;hb=b71ca98d05f8848fa3170d606b7b8a8ef6d274f4;hp=5cdbeb10b8364eeb8b9d0f26047748ffb0a128f3;hpb=86f6122c4537264ac1a6203aaf589f08d725e648;p=jalview.git

diff --git a/src/jalview/util/LinkedIdentityHashSet.java b/src/jalview/util/LinkedIdentityHashSet.java
index 5cdbeb1..bce540f 100644
--- a/src/jalview/util/LinkedIdentityHashSet.java
+++ b/src/jalview/util/LinkedIdentityHashSet.java
@@ -65,7 +65,34 @@ public class LinkedIdentityHashSet<E> extends AbstractSet<E>
   public boolean add(E e)
   {
     IdentityWrapper el = (new IdentityWrapper(e, set.size()));
-    return set.putIfAbsent(el, el) == null;
+    // Map.putIfAbsent() from Java 8
+    // return set.putIfAbsent(el, el) == null;
+    return putIfAbsent(el, el) == null;
+  }
+
+  /**
+   * If the specified key is not already associated with a value (or is mapped
+   * to null) associates it with the given value and returns null, else returns
+   * the current value.
+   * 
+   * Method added for Java 7 (can remove for Java 8)
+   * 
+   * @param key
+   * @param value
+   * @return
+   * @see https
+   *      ://docs.oracle.com/javase/8/docs/api/java/util/Map.html#putIfAbsent
+   *      -K-V-
+   */
+  private IdentityWrapper putIfAbsent(IdentityWrapper key,
+          IdentityWrapper value)
+  {
+    IdentityWrapper v = set.get(key);
+    if (v == null)
+    {
+      v = set.put(key, value);
+    }
+    return v;
   }
 
   @Override
@@ -87,6 +114,13 @@ public class LinkedIdentityHashSet<E> extends AbstractSet<E>
       {
         return (E) se.next().obj;
       }
+
+      @Override
+      public void remove()
+      {
+        // Java 8 default behaviour
+        throw new UnsupportedOperationException();
+      }
     };
   }