Develop Reference

Use of Shared Preferences and Intent - Setup and Settings application

I am currently developing an application that on the first time the application opens, shows the setup interface and the succeeding times the application is opened, it shows the settings interface. The way I achieved this is that once my application opens, it checks if the shared preferences is null. If the shared preferences is null, it means it was the first time that the application is opened and it will set a value in the shared preferences. Then the next time that the application is opened, when the shared preferences is checked, it isn't null anymore and will go to the settings interface. The problem is, When I run it the first time, it only shows a white screen with no status bar or anything. Below are code snippets of my application
private void saveSharedPref()
{
SharedPreferences preferences = getSharedPreferences(SHARED_PREFERENCES_FILE, 0);
SharedPreferences.Editor editor = preferences.edit();
//Save values from Edit Text Controls
editor.putString("firstTime", "1234");
editor.commit();
}
private void loadSharedPreferences()
{
SharedPreferences preferences = getSharedPreferences(SHARED_PREFERENCES_FILE, 0);
//Null check in case file does not exist
if(preferences != null) {
String checkFirst = preferences.getString("firstTime", "");
if (!checkFirst.equalsIgnoreCase("1234"))
{
Intent sendToSetup = new Intent (this, Setup.class);
startActivity(sendToSetup);
}
else
{
saveSharedPref();
}
}
}
I call loadSharedPreferences() in my onCreateMethod
public class Setup extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.setup_pg1);
}
This is where the app gets redirected when the user open it for the first time.
Any help would be greatly appreciated. Thanks in advance!
P.S. sorry if my english isnt good
EDIT:
here's the androidmanifest
<?xml version="1.0" encoding="utf-8"?>
<application
android:allowBackup="true"
android:icon="#drawable/icon1"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity
android:name=".SafeSwipe"
android:label="SafeSwipe-UI v.2"
android:theme="#style/AppTheme.NoActionBar">
</activity>
<activity
android:name=".MainActivity"
android:label=""
android:theme="#style/AppTheme.NoActionBar">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".Setup" />
</application>
setup_pg1
<TextView
android:text="Setup"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="102dp"
android:id="#+id/textView" />
<Button
android:text="Continue"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/textView"
android:layout_alignRight="#+id/textView"
android:layout_alignEnd="#+id/textView"
android:layout_marginTop="71dp"
android:id="#+id/button7" />
setup file
public class Setup extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.setup_pg1);
}
}

First, if(preferences != null) will never be true because you'll always get a non-null value from getSharedPreferences()
I call loadSharedPreferences() in my onCreate Method
No you don't... here's your code
public class Setup extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.setup_pg1);
}
}
Try again. But use a boolean value rather than some random string.
public class MainActivity extends AppCompatActivity {
public static final String PREFS_NAME = "MyPrefsFile";
public static final String KEY_FIRST_TIME = "firstTime";
#Override
protected void onCreate(Bundle b){
super.onCreate(b);
setContentView(R.layout.activity_main);
SharedPreferences prefs = getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
boolean firstTime = prefs.getBoolean(KEY_FIRST_TIME, false);
if (!firstTime) {
SharedPreferences.Editor editor = prefs.edit();
editor.putBoolean(KEY_FIRST_TIME, true);
editor.commit();
} else {
Intent sendToSetup = new Intent (this, Setup.class);
startActivity(sendToSetup);
finish();
}
}
}

Try this:
Instead of checking preferences != null try this..
if (preferences.getString("firstTime","").equals("1234"))
{
Intent sendToSetup = new Intent (this, Setup.class);
startActivity(sendToSetup);
}
else
saveSharedPref();

Your if(preferences != null)is not working here, cause preferences is not null. It's just an empty preference. You can try out the below code:
private void loadSharedPreferences()
{
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
String checkFirst = preferences.getString("firstTime", "");
if(!checkFirst.equals("")) {
Intent sendToSetup = new Intent (this, Setup.class);
startActivity(sendToSetup);
}
else
{
saveSharedPref();
}
}
saveSharedPref() method:
private void saveSharedPref()
{
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);
//Save values from Edit Text Controls
preferences.edit().putString("firstTime", "1234").apply();
}
Call loadSharedPreferences() in onCreate() of Setup Activity:
Hope this helps.

I don't see any crucial problem in this code. But I have some assumption that you have already called the saveSharedPref() method while testing your program and value of firstTime is already exist. Because SharedPreferences are not deleted after recompiling the program this statement:
if (!checkFirst.equalsIgnoreCase("1234"))
gives false.
The best way to check this is to set a breakpoint in loadSharedPreferences() method and verify it.
If it is so try to remove sharedPreferences (see the answer https://stackoverflow.com/a/3687333/7677939 )
or simply give another file name in SHARED_PREFERENCES_FILE variable.
Also it can be a problem in place where you call loadSharedPreferences(), but I cannot see it in your source.
Update:
Notice, that you should not call loadSharedPreferences() in Setup activity, you should call it in your Main activity!

BackUpAgentHelperClass is not getting called

I want to backup data in Android using MyBackUpAgent class which extends BackupAgentHelper. I am using SharedPreferences in order to store data.
My mainactivity code is:
public class MainActivity extends Activity {
EditText inputtext;
TextView outputtext;
Button submit;
public static SharedPreferences sharedprefs;
static final String File_Name_Of_Prefrences ="godplay_preferences";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main2);
init();
sharedprefs=getSharedPreferences(File_Name_Of_Prefrences,MODE_PRIVATE);
System.out.println("value="+sharedprefs.getString("Input",""));
outputtext.setText(sharedprefs.getString("Input",""));
submit.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
populateUI();
}
});
}
public void populateUI()
{
String savedinput=inputtext.getText().toString();
System.out.println("savedinput="+savedinput);
outputtext.setText(savedinput);
sharedprefs=getSharedPreferences(File_Name_Of_Prefrences,MODE_PRIVATE);
Editor editor=sharedprefs.edit();
editor.putString("Input",inputtext.getText().toString());
editor.commit();
requestBackup();
}
private void init() throws ClassCastException
{
inputtext=(EditText) findViewById(R.id.edtInputText);
outputtext=(TextView) findViewById(R.id.txtOutputText);
submit=(Button) findViewById(R.id.btnSubmit);
}
public void requestBackup() {
BackupManager bm = new BackupManager(getApplicationContext());
bm.dataChanged();
}
}
My MyBackUpAgent class:
public class MyBackUpAgent extends BackupAgentHelper{
static final String PREFS_BACKUP_KEY = "backup";
String key_string="Hello World";
#Override
public void onCreate() {
System.out.println("********************");
SharedPreferencesBackupHelper helper = new SharedPreferencesBackupHelper(this,MainActivity.File_Name_Of_Prefrences);
addHelper(PREFS_BACKUP_KEY, helper);
}
}
My mainfest.xml file:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.godplay"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:restoreAnyVersion="false"
android:backupAgent=".MyBackUpAgent"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.godplay.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<meta-data android:name="com.google.android.backup.api_key" android:value="AEdPqrEAAAAIhjloadYCTPUNo3yPsSX6LKmziiumZiQVlEEdBA" />
</application>
</manifest>
So far I have tried with bmgr tool to test, it is executing successfully with bmgr tool. However, on testing on Android device and emulator, back up is not happening, nor restoring.
Also, I have tested this on Android 5.1, Android 4.2, and Android 4.0 but still no luck.
It seems to me that my MyBackUpAgent class is never getting called, and I have tried breakpoints in MyBackUpAgent Class and validated it. Its never get hit.
What am I doing wrong?

Docs mention Conditions For Backup Schedule:
The user has enabled backup on the device in Settings > Backup & Reset.
At least 24 hours have elapsed since the last backup.
The device is idle and charging.
The device is connected to a Wi-Fi network. If the device is never connected to a wifi network, then Auto Backup never occurs.
If backup is working for you with bmgr tool but not on a real device / emulator, it's possible you are not meeting all those conditions, therefore backup never occur.

In your AndroidManifest.xml file, try changing
android:backupAgent=".MyBackUpAgent"
with the fully qualified class name, i.e.
android:backupAgent="com.abh.utils.MyBackUpAgent"
but of course changing "com.abh.utils" with the name of the package MyBackUpAgent.java is in.

I had a similar problem and have searched everywhere with no luck. Finally found the solution.
It seems that the BackupAgent needs to be in the top package with no preceding dot. So try changing:
android:backupAgent=".MyBackUpAgent"
to
android:backupAgent="MyBackUpAgent"

You can refer to developer document,
https://developer.android.com/guide/topics/data/backup.html#PerformingBackup
A backup request does not result in an immediate call to your onBackup() method. Instead, the Backup Manager waits for an appropriate time
you can use "bmgr tool" to initiate immediate backup whiling developing your app.

Make sure you call
adb shell bmgr run
to simulate the backup.
Also try using local transport to backup at any time:
adb shell bmgr transport android/com.android.internal.backup.LocalTransport

BackupAgentHelper never called in Android 2.2

I'm trying to implement Data Backup into my application. I build Android 2.2 project, and run in Galaxy s2 4.0.3.
I try to use: BackupManagerTest to save preferences to the cloud
This is my code :
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="net.amdroid.backuptest"
android:versionCode="1"
android:versionName="1.0" >
<uses-permission android:name="android.permission.INTERNET" />
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="8" />
<application
android:allowBackup="true"
android:backupAgent="net.amdroid.backuptest.MyBackupAgent"
android:icon="#drawable/icon"
android:label="#string/app_name" >
<activity
android:name=".BackupManagerTestActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<meta-data
android:name="com.google.android.backup.api_key"
android:value="AEdPqrEAAAAI7_yf1xqlpltWZPZiKMHVlDgn3nMfgotjUweSUg" />
</application>
</manifest>
MyBackupAgent.java
public class MyBackupAgent extends BackupAgentHelper {
// The names of the SharedPreferences groups that the application maintains. These
// are the same strings that are passed to getSharedPreferences(String, int).
static final String PREFS_TEST = "testprefs";
// An arbitrary string used within the BackupAgentHelper implementation to
// identify the SharedPreferenceBackupHelper's data.
static final String MY_PREFS_BACKUP_KEY = "myprefs";
// Simply allocate a helper and install it
#Override
public void onCreate() {
SharedPreferencesBackupHelper helper =
new SharedPreferencesBackupHelper(this, PREFS_TEST);
addHelper(MY_PREFS_BACKUP_KEY, helper);
Log.d("Test", "Adding backupagent...");
}
}
My Activity
public class BackupManagerTestActivity extends Activity {
private SharedPreferences prefs;
private Editor edit;
private BackupManager backupManager;
private EditText text;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
backupManager = new BackupManager(getBaseContext());
prefs = getSharedPreferences(MyBackupAgent.PREFS_TEST, Context.MODE_PRIVATE);
edit = prefs.edit();
text = (EditText) findViewById(R.id.editName);
String nome = prefs.getString("KEY_NAME", "");
text.setText(nome);
Button button = (Button) findViewById(R.id.buttonSave);
button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
edit.putString("KEY_NAME", text.getText().toString());
edit.commit();
Log.d("Test", "Calling backup...");
backupManager.dataChanged();
}
});
}
}
So MyBackupAgent never called. I don't know the reason.

When you call backupManager.dataChanged(), it merely schedules your app for backup. It does not mean your backup helper is called right away.
From http://developer.android.com/guide/topics/data/backup.html:
You can request a backup operation at any time by calling dataChanged(). This method notifies the Backup Manager that you'd like to backup your data using your backup agent. The Backup Manager then calls your backup agent's onBackup() method at an opportune time in the future. Typically, you should request a backup each time your data changes (such as when the user changes an application preference that you'd like to back up). If you call dataChanged() several times consecutively, before the Backup Manager requests a backup from your agent, your agent still receives just one call to onBackup().
Note: While developing your application, you can request a backup and initiate an immediate backup operation with the bmgr tool.
Instructions for the bmgr tool can be found at:
http://developer.android.com/tools/help/bmgr.html
To force all pending backup operations to run immediately, use:
adb shell bmgr run

Android preferences problem

I am following this tutorial: link text
Preferences.java:
public class Preferences extends PreferenceActivity{
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.preferences);
}
}
PreferencesTutorial.java:
public class PreferencesTutorial extends Activity{
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button prefBtn = (Button) findViewById(R.id.prefButton);
prefBtn.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Intent settingsActivity = new Intent(getBaseContext(),
Preferences.class);
startActivity(settingsActivity);
}
});
}
}
Preferences.xml:
When application starts, and i click the prefButton, an error occures: "The application PreferencesTutorial (process PreferencesTutorial.com.examples) has stopped unexpectedly. Please try again"
I haven't found any mistakes in the code.
I would also like to show my filestructure if that helps:
AndroidManifest.xml:
What is wrong with the code?
Even if i add (where the cursor is)
<activity
android:name=".Preferences"
android:label="#string/set_preferences">
</activity>
i still get the error.

Try removing this import, if you have it;
import java.util.prefs.Preferences;

You have to mention this in your androidManifest.xml file
<activity
android:name=".Preferences"
android:label="#string/set_preferences">
<intent-filter>
<category android:name="android.intent.category.DEFAULT"/>
</intent-filter>
</activity>

You probably do not have Preferences defined in your manifest.
However, as others have indicated, use adb logcat, DDMS, or the DDMS perspective in Eclipse to examine LogCat and see the stack trace associated with your crash.

Is the error raised in the OnClick in PreferencesTutorial Class or onCreate in the preferences Class? Stick a couple of Log.d("Debug","%ID") in various locations and see which one doesn't get called.

Data Backup into Google Servers using Android Backup Service in Android

Im trying to do the backing up of my application's data into the Google Servers..
For doing this I've implemented a BackupAgent in my code and I included this in the Android Manifest file and "Meta-data" ( Got after registered my Application's package with the Android Backup Service)
When I run the application to do the backup this is not performing the backup.. Im using Nexus one device (connected to WIFI also) .
Could any one please let me know why it is not calling my BackupAgent's onBackup() method?
Am I missing some thing, to include in the Android manifest file or some where in the program?
The below is my manifest file..
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="org.simpledatabackup"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="#drawable/icon" android:label="#string/app_name"
android:backupAgent="MyBackupAgent"
android:debuggable="true">
<activity android:name=".SimpleDatabackup"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<meta-data android:name="com.google.android.backup.api_key"
android:value="AEdPqrEAAAAIZn2ysSLR5wNbcq1uaoWQO0HuipMetQENVTsilw" />
</application>
<uses-sdk android:minSdkVersion="8" />
</manifest>
and the source file is
public class SimpleDatabackup extends Activity {
private SharedPreferences myPrefs ; // Shared Preferences
BackupManager mBackupManager;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
myPrefs = this.getSharedPreferences("shared_prefs", MODE_WORLD_READABLE);
SharedPreferences.Editor edit = myPrefs.edit();
edit.putString("firstname", "uday") ;
edit.putString("lastname", "kiran") ;
edit.commit() ;
mBackupManager.dataChanged();
}
}
My Backup Agent is some thing like this: I have not implemented the functionality inside is onBackup() and onRestore(). Once if it is called i will implement what ever i want..
public class MyBackupAgent extends BackupAgent {
#Override
public void onCreate() {
System.out.println("In MyBackuAgent's onCreate() method");
}
#Override
public void onBackup(ParcelFileDescriptor arg0, BackupDataOutput arg1,
ParcelFileDescriptor arg2) throws IOException {
System.out.println("In MyBackuAgent's onBackup()");
// TODO Auto-generated method stub
}
#Override
public void onRestore(BackupDataInput data, int appVersionCode,
ParcelFileDescriptor newState) throws IOException {
}
}

In the application tag in the manifest include
android:allowBackup="true"
android:restoreAnyVersion="true"
android:backupAgent="<package>.MyBackupAgent"
Please follow the "Testing your BackupAgent" section to invoke the backup instantly for testing.
BackupManagerService schedules the backup regularly in hour interval after the datachanged call to backupmanager. [grepcode]