Adding new samples to browseable section of DAC

Change-Id: I58e10e787f5df668331fc04e97a6c2efcd75f76f

samples/browseable/CardEmulation/src/com.example.android.cardemulation/AccountStorage.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2013 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.example.android.cardemulation;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.preference.PreferenceManager;
+import android.util.Log;
+
+/**
+ * Utility class for persisting account numbers to disk.
+ *
+ * <p>The default SharedPreferences instance is used as the backing storage. Values are cached
+ * in memory for performance.
+ *
+ * <p>This class is thread-safe.
+ */
+public class AccountStorage {
+    private static final String PREF_ACCOUNT_NUMBER = "account_number";
+    private static final String DEFAULT_ACCOUNT_NUMBER = "00000000";
+    private static final String TAG = "AccountStorage";
+    private static String sAccount = null;
+    private static final Object sAccountLock = new Object();
+
+    public static void SetAccount(Context c, String s) {
+        synchronized(sAccountLock) {
+            Log.i(TAG, "Setting account number: " + s);
+            SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(c);
+            prefs.edit().putString(PREF_ACCOUNT_NUMBER, s).commit();
+            sAccount = s;
+        }
+    }
+
+    public static String GetAccount(Context c) {
+        synchronized (sAccountLock) {
+            if (sAccount == null) {
+                SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(c);
+                String account = prefs.getString(PREF_ACCOUNT_NUMBER, DEFAULT_ACCOUNT_NUMBER);
+                sAccount = account;
+            }
+            return sAccount;
+        }
+    }
+}