Completed Homework 2

TaskManager/src/com/sudarmuthu/android/taskmanager/TaskManagerApplication.java

@@ -1,21 +1,41 @@
 package com.sudarmuthu.android.taskmanager;
 
+import java.io.IOException;
 import java.util.ArrayList;
 
 import android.app.Application;
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.content.SharedPreferences.Editor;
+import android.util.Log;
 
 import com.sudarmuthu.android.taskmanager.tasks.Task;
+import com.sudarmuthu.android.taskmanager.util.ObjectSerializer;
 
 public class TaskManagerApplication extends Application {
 
+	private static final String SHARED_PREFS_FILE = "shared_prefs_file";
+	private static final String TASKS = "tasks";
 	private ArrayList<Task> currentTasks;
 
+	@SuppressWarnings("unchecked")
 	@Override
 	public void onCreate() {
 		super.onCreate();
 		if (null == currentTasks) {
 			currentTasks = new ArrayList<Task>();
 		}
+
+		//		load tasks from preference		
+		SharedPreferences prefs = getSharedPreferences(SHARED_PREFS_FILE, Context.MODE_PRIVATE);
+
+		try {
+			currentTasks = (ArrayList<Task>) ObjectSerializer.deserialize(prefs.getString(TASKS, ObjectSerializer.serialize(new ArrayList<Task>())));
+		} catch (IOException e) {
+			e.printStackTrace();
+		} catch (ClassNotFoundException e) {
+			e.printStackTrace();
+		}		
 	}
 
 	public void setCurrentTasks(ArrayList<Task> currentTasks) {
@@ -32,5 +52,15 @@ public void addTask(Task t) {
 			currentTasks = new ArrayList<Task>();
 		}
 		currentTasks.add(t);
+
+		//save the task list to preference
+		SharedPreferences prefs = getSharedPreferences(SHARED_PREFS_FILE, Context.MODE_PRIVATE);		
+		Editor editor = prefs.edit();
+		try {
+			editor.putString(TASKS, ObjectSerializer.serialize(currentTasks));
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+		editor.commit();
 	}
 }

TaskManager/src/com/sudarmuthu/android/taskmanager/tasks/Task.java

@@ -1,6 +1,13 @@
 package com.sudarmuthu.android.taskmanager.tasks;
 
-public class Task {
+import java.io.Serializable;
+
+public class Task implements Serializable{
+	/**
+	 * 
+	 */
+	private static final long serialVersionUID = 1L;
+
 	private String name;
 
 	public Task(String taskName) {
@@ -17,6 +24,5 @@ public void setName(String name) {
 
 	public String toString() {
 		return name;
-	}
-
-}
+	}	
+}

TaskManager/src/com/sudarmuthu/android/taskmanager/util/ObjectSerializer.java

@@ -0,0 +1,70 @@
+package com.sudarmuthu.android.taskmanager.util;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ */
+
+//copied from http://github.com/apache/pig/blob/89c2e8e76c68d0d0abe6a36b4e08ddc56979796f/src/org/apache/pig/impl/util/ObjectSerializer.java 
+//package org.apache.pig.impl.util;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+
+public class ObjectSerializer {
+
+    public static String serialize(Serializable obj) throws IOException {
+        if (obj == null) return "";
+        ByteArrayOutputStream serialObj = new ByteArrayOutputStream();
+        ObjectOutputStream objStream = new ObjectOutputStream(serialObj);
+        objStream.writeObject(obj);
+        objStream.close();
+        return encodeBytes(serialObj.toByteArray());
+    }
+
+    public static Object deserialize(String str) throws IOException, ClassNotFoundException {
+        if (str == null || str.length() == 0) return null;
+        ByteArrayInputStream serialObj = new ByteArrayInputStream(decodeBytes(str));
+        ObjectInputStream objStream = new ObjectInputStream(serialObj);
+        return objStream.readObject();
+    }
+
+    public static String encodeBytes(byte[] bytes) {
+        StringBuffer strBuf = new StringBuffer();
+
+        for (int i = 0; i < bytes.length; i++) {
+            strBuf.append((char) (((bytes[i] >> 4) & 0xF) + ((int) 'a')));
+            strBuf.append((char) (((bytes[i]) & 0xF) + ((int) 'a')));
+        }
+
+        return strBuf.toString();
+    }
+
+    public static byte[] decodeBytes(String str) {
+        byte[] bytes = new byte[str.length() / 2];
+        for (int i = 0; i < str.length(); i+=2) {
+            char c = str.charAt(i);
+            bytes[i/2] = (byte) ((c - 'a') << 4);
+            c = str.charAt(i+1);
+            bytes[i/2] += (c - 'a');
+        }
+        return bytes;
+    }
+}