Develop Reference

How to make an android app remember my username?

I made a chat room app which asks the user to enter its username every time i open it. How can i make it remember me? I am using fire-base for the back end.
See Code Here

Create Shared Preference class where first time when user enter his/her username store it.
You can read more about Shared Preference here
The for you as follows
public class SharePref {
public static final String PREF_NAME = "chatroom.shared.pref";
public static final String PREF_KEY = "chatroom.shared.username";
public SharePref() {
}
public void save(Context context, String text) {
SharedPreferences sharePref;
SharedPreferences.Editor editor;
sharePref = context.getSharedPreferences(PREF_NAME,Context.MODE_PRIVATE);
editor = sharePref.edit();
editor.putString(PREF_KEY,text);
editor.apply();
}
public String getData(Context context) {
SharedPreferences sharePref;
String text;
sharePref = context.getSharedPreferences(PREF_NAME,Context.MODE_PRIVATE);
text = sharePref.getString(PREF_KEY,null);
return text;
}
}
Now in your MainActivity you can check if you have already stored the username for user
inside your onCreate()
SharePref sharePref = new SharePref();
String UserName = sharePref.getData(mContext);
if(UserName == null) {
String value = //username value;
SharePref sharePref = new SharePref();
sharePref.save(context,value);
}
else {
// you already have username do your stuff
}
Hope this will help

You can use shared preference. Say you are saving username in String called User. To save username:
SharedPreferences shareit = getSharedPreferences("KEY",Context.MODE_PRIVATE);
SharedPreferences.Editor eddy = shareit.edit();
eddy.putString("AKEY", User);
eddy.commit();
And everytime user login:
SharedPreferences sharedPreferences = getContext().getSharedPreferences("KEY", Context.MODE_PRIVATE);
String getName = sharedPreferences.getString("AKEY", "");
String getName will have the value of your username. The "KEY" and "AKEY" used above are to give special id to different values saved via shared preference.

SharedPreferencec prefs = getSharedPreferences("username",Context.MODE_PRIVATE);
SharedPreference.Editor editor = prefs.edit();
if (!prefs.getString("username",null)
//do the chatting
else {
//show dialog to get username
//now save it in shared preferences
editor.putString("username",username);
editor.commit();
}

Android Preference old and new value compare

I have got NewValue from activity1 and store on preference and compare with OldValue from activity2: my problem it dose not store oldValue..
on activity 1:
int i = 5;
SharedPreferences prefs1 = getPreferences(0);
SharedPreferences.Editor editor = getPreferences(0).edit();
editor.putInt("new", i);
editor.commit();
on activity 2:
SharedPreferences prefs1 = getPreferences(0);
int oldValue = prefs1.getInt("old", 0);
int newValue = prefs1.getInt("new", 0);
/* Should Activity Check for Updates Now? */
if (oldValue < newValue) {
/* Save current newValue for next Check */
SharedPreferences.Editor editor = getPreferences(0).edit();
editor.putInt("old", newValue);
editor.commit();
do something....
}

Well, if you want share preferences with activities then you need to use getSharedPreferences(String, int) but you are using getSharedPreferences(int)
getSharedPreferences(int) Retrieve a SharedPreferences object for accessing preferences that are private to this activity. This simply calls the underlying getSharedPreferences(String, int) method by passing in this activity's class name as the preferences name.
get SharedPreference object like this
SharedPreferences prefs1 =getSharedPreferences ("app_prefs", Context.MODE_PRIVATE);

is the key of newValue is "new" or "newValue" ? you saved it with key and retrieving with the other
So it won't find the newValue so it will be always equals zero
editor.putInt("newValue", 5);
int newValue = prefs1.getInt("new", 0);
So you newValue will equal 0 because no key "new" in prefrences

How to save value in SharedPeference in the actitvity and access it all other classes

I want to save totalBalance in this activity to SharedPreferances and the retrive it in another class.
so i want totalbalance to be displayed in another activities in same application...
if possible also edit it in other activites...
please help... thanks
button1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Do something in response to button click
// Genrating random number Random number
Random rn = new Random();
randomNumber = (int) rn.nextInt(9) + 1;
// changes textView1 equals to random number
textView1.setText("Random Number is "
+ Integer.toString(randomNumber));
button1.setText("Play Again");
// Matching random number to ArrayList
if (positive_IDs.contains(randomNumber)) {
// if matched then changes textView2 to Matched Number
textView2.setText("Number: "
+ Integer.toString(randomNumber) + " Matched");
totalBalance = totalBalance + winingPrize;
textView5.setText("Total Balance = Rs: "
+ String.format("%.2f", totalBalance));
}
}

try this,
public void saveValue(String lock, Context context) {
Editor editor = context
.getSharedPreferences(KEY, Activity.MODE_PRIVATE).edit();
editor.putString("Value", lock);
editor.commit();
}
public String getValue(Context context) {
SharedPreferences savedvalue = context.getSharedPreferences(KEY,
Activity.MODE_PRIVATE);
return savedvalue.getString("Value", "");
}

Save Value as Following
int Value;
private void saveValues(){
SharedPreferences readSP = getSharedPreferences("String", MODE_PRIVATE);
SharedPreferences.Editor editor = readSP.edit();
editor.putString("String", Value);
editor.commit();
}
Retrive value in any of your Class As following
int value;
private void getSavedValue()
{
SharedPreferences settings = getSharedPreferences("String", MODE_PRIVATE);
value=settings.getString("String", "");
}

// try this
SharedPreferences sharedPreferences = getSharedPreferences("yourSharePreferenceName", MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putBoolean("balance", String.format("%.2f", totalBalance));
editor.commit();
SharedPreferences sharedPreferences = getSharedPreferences("yourSharePreferenceName", MODE_PRIVATE);
String total = sharedPreferences.getString("balance");

Use following code to retrive your value from SharedPreference,write this in other class where you want to retrive value of total balance
SharedPreferences pref = PreferenceManager.getDefaultSharedPreferences(YourActivityName.this);
Editor edit1 = remembermepref.edit();
edit1.putInt("totalbalance_key",totalBalance);
edit1.commit();
and to store total balance into ShardPreference use in your activity:
SharedPreferences pref = PreferenceManager.getDefaultSharedPreferences(YourActivityName.this);
int totalbalance = pref.getInt("totalbalance_key");
Now use totalbalance way you want.
Most important thing is to check whether you have used same key to restore as well as tostore the value in SharedPreference
Hope this helps..

Access to SharedPreferences from different activity

In first (MainActivity) I save data trough SharedPreferences:
Editor editor = mGameSettings.edit();
editor.putString(GAME_PREFERENCES_SHOP, Shops.get(lv.getCheckedItemPosition()));
editor.commit();
And I can read this data from MainActivity after restart application:
if (mGameSettings.contains(GAME_PREFERENCES_SHOP))
Tv2.setText(mGameSettings.getString(GAME_PREFERENCES_SHOP, ""));
But how to read and edit this SharedPreferences from other activity?

Write the Below code in your another activity:
SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(this);
if (sp.contains(MainActivity.GAME_PREFERENCES_SHOP)) //hoping that GAME_PREFERENCES_SHOP is a static constant defined in MainActivity
Tv2.setText(sp.getString(MainActivity.GAME_PREFERENCES_SHOP, ""));

You can use below code for getting the preference value from different Application
Context launcherContext = null;
try {
final int flags = Context.CONTEXT_IGNORE_SECURITY | Context.CONTEXT_INCLUDE_CODE;
launcherContext = getApplicationContext().createPackageContext("com.another.package", flags);
} catch (final NameNotFoundException e) {
return ;
}
final SharedPreferences pref = launcherContext.getSharedPreferences(
"prefname",
Context.MODE_WORLD_READABLE | Context.MODE_MULTI_PROCESS);
final String prefValue = pref.getString("prefname", null);
Log.i("test", prefValue);

You can read and edit with the same code. You just have to use the same Prefs file name and key for the required value.
You can declare your Pref File name as public static final String PREFS_NAME = "MyPrefsFile"; in the main activity and then access it from anywhere in the application.
Example, in other Activity:
SharedPreferences mGameSettings = getSharedPreferences(MainActivity.PREFS_NAME, MODE_PRIVATE);
if (mGameSettings.contains(MainActivity.GAME_PREFERENCES_SHOP))
Tv2.setText(mGameSettings.getString(MainActivity.GAME_PREFERENCES_SHOP, ""));

SharedPreferences keep getting default value

I keep Getting the Default value either my UI will display null or if I use integers it displays that default value as well here it is in the string form plz help
//putting the information in shared preferences
TextView pScore1=(TextView)findViewById(R.id.pScore1f);
SharedPreferences peepsScores2= PreferenceManager.getDefaultSharedPreferences(GamePlayFirst.this);
SharedPreferences.Editor editor2 =peepsScores2.edit();
String userScore11 = pScore1.getText().toString();
editor2.putString("userScore11",userScore11);
editor2.commit();
//getting it and editing it
SharedPreferences peepsScores2 = PreferenceManager.getDefaultSharedPreferences(this);
int u;
int one =1;
int newUsrScore1=1;
String userScore11 = peepsScores2.getString("userScore11",null);
u=Integer.parseInt(userScore11);
newUsrScore1 = u+one;
String newUserScore1 = Integer.toString(newUsrScore1);
SharedPreferences.Editor editor = peepsScores2.edit();
editor.putString(newUserScore1, NewUserScore1);
editor.commit();
//getting it and displaying it on the UI
SharedPreferences peepsScores2 = PreferenceManager.getDefaultSharedPreferences(this);
String userScore11 = peepsScores2.getString("NewuserScore1",null);
pScore1.setText(" "+userScore11);

I have added some comment to you code please check:
//putting the information in shared preferences
TextView pScore1=(TextView)findViewById(R.id.pScore1f);
SharedPreferences peepsScores2=
PreferenceManager.getDefaultSharedPreferences(GamePlayFirst.this);
SharedPreferences.Editor editor2 =peepsScores2.edit();
String userScore11 = pScore1.getText().toString();
editor2.putString("userScore11",userScore11);
editor2.commit();
//getting it and editing it
SharedPreferences peepsScores2 = PreferenceManager.getDefaultSharedPreferences(this);
int u;
int one =1;
int newUsrScore1=1;
String userScore11 = peepsScores2.getString("userScore11",null);
u=Integer.parseInt(userScore11);
newUsrScore1 = u+one;
String newUserScore1 = Integer.toString(newUsrScore1);
SharedPreferences.Editor editor = peepsScores2.edit();
//#Praful: here newUserScore1 seems to be integer value and you are storing
//null here. I think it it should be
//`editor.putString("NewuserScore1", newUsrScore1);`
editor.putString(newUserScore1, null);
//#Praful: call commit here
editor.commit;
//getting it and displaying it on the UI
SharedPreferences peepsScores2 = PreferenceManager.getDefaultSharedPreferences(this);
String userScore11 = peepsScores2.getString("NewuserScore1",null);
pScore1.setText(" "+userScore11);

This line
editor.putString(newUserScore1, null);
should be
editor.putString("NewuserScore1",newUserScore1);
and also don't forget to commit your changes using editor.commit();

Whenever you working with SharedPreference never forget to call commit() to save your changes.
SharedPreferences.Editor editor = peepsScores2.edit();
editor.putString("NewuserScore1", newUserScore1);
editor.commit();