diff --git a/src/com/android/calculator2/AlertDialogFragment.java b/src/com/android/calculator2/AlertDialogFragment.java
new file mode 100644
index 0000000..bb7a50b
--- /dev/null
+++ b/src/com/android/calculator2/AlertDialogFragment.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * 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
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * 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.android.calculator2;
+
+import android.app.Activity;
+import android.app.AlertDialog;
+import android.app.Dialog;
+import android.app.DialogFragment;
+import android.content.Context;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.widget.TextView;
+
+public class AlertDialogFragment extends DialogFragment {
+
+    private static final String NAME = AlertDialogFragment.class.getName();
+    private static final String KEY_MESSAGE = NAME + "_message";
+    private static final String KEY_BUTTON_NEGATIVE = NAME + "_button_negative";
+
+    public static void showMessageDialog(Activity activity, CharSequence message) {
+        final Bundle args = new Bundle();
+        args.putCharSequence(KEY_MESSAGE, message);
+        args.putCharSequence(KEY_BUTTON_NEGATIVE, activity.getString(R.string.dismiss));
+
+        final AlertDialogFragment dialogFragment = new AlertDialogFragment();
+        dialogFragment.setArguments(args);
+        dialogFragment.show(activity.getFragmentManager(), null /* tag */);
+    }
+
+    public AlertDialogFragment() {
+        setStyle(STYLE_NO_TITLE, android.R.attr.alertDialogTheme);
+    }
+
+    @Override
+    public Dialog onCreateDialog(Bundle savedInstanceState) {
+        final Bundle args = getArguments() == null ? Bundle.EMPTY : getArguments();
+        final Context context = getContext();
+        final LayoutInflater inflater = LayoutInflater.from(context);
+        final TextView textView = (TextView) inflater.inflate(R.layout.dialog_message,
+                null /* root */);
+        textView.setText(args.getCharSequence(KEY_MESSAGE));
+        return new AlertDialog.Builder(context)
+                .setView(textView)
+                .setNegativeButton(args.getCharSequence(KEY_BUTTON_NEGATIVE), null /* listener */)
+                .create();
+    }
+}