Add hint to search bar

app/src/main/java/com/hippo/util/Messenger.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2015 Hippo Seven
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.hippo.util;
+
+import android.util.SparseArray;
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class Messenger {
+
+    private IntIdGenerator mIdGenerator;
+
+    private SparseArray<Set<Receiver>> mReceiverSetMap;
+
+    private static Messenger sInstance;
+
+    public static Messenger getInstance() {
+        if (sInstance == null) {
+            sInstance = new Messenger();
+        }
+        return sInstance;
+    }
+
+    private Messenger() {
+        mIdGenerator = IntIdGenerator.create();
+        mReceiverSetMap = new SparseArray<>();
+    }
+
+    public int newId() {
+        return mIdGenerator.nextId();
+    }
+
+    public void notify(final int id, final Object obj) {
+        // Make sure do it in UI thread
+        AppHandler.getInstance().post(new Runnable() {
+            @Override
+            public void run() {
+                Set<Receiver> receiverSet = mReceiverSetMap.get(id);
+                if (receiverSet != null) {
+                    for (Receiver receiver : receiverSet) {
+                        receiver.onReceive(id, obj);
+                    }
+                }
+            }
+        });
+    }
+
+    public void register(int id, Receiver receiver) {
+        Set<Receiver> receiverSet = mReceiverSetMap.get(id);
+        if (receiverSet == null) {
+            receiverSet = new HashSet<>();
+            mReceiverSetMap.put(id, receiverSet);
+        }
+
+        receiverSet.add(receiver);
+    }
+
+    public void unregister(int id, Receiver receiver) {
+        Set<Receiver> receiverSet = mReceiverSetMap.get(id);
+        if (receiverSet != null) {
+            receiverSet.remove(receiver);
+            if (receiverSet.isEmpty()) {
+                mReceiverSetMap.remove(id);
+            }
+        }
+    }
+
+    public interface Receiver {
+        void onReceive(final int id, final Object obj);
+    }
+}