Saving and restoring text when rotating

Question

I have seen a few examples on how to achieve this but still I can't get it working.

I followed this example, but the TextView is empty in OnCreate and when I rotate the screen. Here is how I implemented it:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.activity_image_viewer);

    displayFileName = (TextView) findViewById(R.id.displayFileName);

    //Getting the fileName
    Bundle extras = getIntent().getExtras();
    uri = extras.getString("uriAsString");
    Uri myUri = Uri.parse(uri);
    filename = uri.substring(uri.lastIndexOf("/") + 1);
    nameWitoutExtention = filename.substring(0, filename.lastIndexOf('.'));

    //Checking if Text was stored
    if (savedInstanceState != null) {
        CharSequence savedText = savedInstanceState.getCharSequence(KEY_TEXT_VALUE);
        displayFileName.setText(savedText);
    }

}

@Override
protected void onSaveInstanceState (Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putCharSequence(KEY_TEXT_VALUE, displayFileName.getText());
}

What I'm trying to achieve is to set nameWitoutExtention to displayFileName and when the device is rotated to let the text remain.

I got a null pointer on the text and that is why I'm trying this, any help on what I'm doing wrong?

EDIT:

This is how my implementation looks like at the moment:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.activity_image_viewer);

    displayFileName = (TextView) findViewById(R.id.displayFileName);

    if(savedInstanceState != null){
        CharSequence savedText = savedInstanceState.getCharSequence(KEY_TEXT_VALUE);

        //When displaying this toast the correct filename gets displayed
        //Toast.makeText(getApplicationContext(), savedText, Toast.LENGTH_LONG).show();

        displayFileName.setText(savedText+"");
    }
    else{
        //Getting the fileName
        Bundle extrsas = getIntent().getExtras();
        uri = extrsas.getString("selectedStudentVid");
        Uri mUri = Uri.parse(uri);
        filename = uri.substring(uri.lastIndexOf("/") + 1);
        nameWitoutExtention = filename.substring(0, filename.lastIndexOf('.'));
        displayFileName.setText(nameWitoutExtention);
    }

@Override
protected void onSaveInstanceState (Bundle outState) {
    super.onSaveInstanceState(outState);      
    outState.putCharSequence(KEY_TEXT_VALUE, displayFileName.getText());
}

I have also tried onRestoreInstanceState() as suggested by @PorasBhardwaj

The exception I'm getting is:

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference

Poras Bhardwaj · Answer 1 · 2017-11-17T07:52:56.673

2

Try using onRestoreInstanceState() callback method to get saved data.

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
 // TODO Auto-generated method stub
 super.onRestoreInstanceState(savedInstanceState);
 CharSequence savedText = savedInstanceState.getCharSequence(KEY_TEXT_VALUE);
 displayFileName.setText(savedText);
}

As per official documentation.

Most implementations will simply use onCreate(Bundle) to restore their state, but it is sometimes convenient to do it here after all of the initialization has been done or to allow subclasses to decide whether to use your default implementation.

So for best practice, keep your view hierarchy in onCreate and restore the previous state in onRestoreInstanceState.

edited Nov 17 '17 at 07:52

answered Nov 17 '17 at 07:40

Poras Bhardwaj

1,073
1
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By the way onRestoreInstanceState is called after onCreate() of activity. So we can get the saved values in onCreate as well. he's doing right there :) – Umair Nov 17 '17 at 07:43
Yes I get `Bundle` in `OnCreate` as well. – ClassA Nov 17 '17 at 07:50
I have tried this as well but I still get null pointer at `displayFileName.setText(savedText);`, I'm sure that `nameWitoutExtention` is not empty, I have tested it. – ClassA Nov 17 '17 at 07:57
@ClassA Can you please update error log in your question. So we can know on which line you are getting the NullPointer. – Poras Bhardwaj Nov 17 '17 at 07:59

Umair · Accepted Answer · 2017-11-17T08:05:58.937

1

Try doing it this way:

//Checking if Text was stored
 if(savedInstanceState != null){
       CharSequence savedText = 
      savedInstanceState.getCharSequence(KEY_TEXT_VALUE);
      displayFileName.setText(savedText + "");
 }
else{
 //Getting the fileName
Bundle extras = getIntent().getExtras();
uri = extras.getString("uriAsString");
Uri myUri = Uri.parse(uri);
filename = uri.substring(uri.lastIndexOf("/") + 1);
nameWitoutExtention = filename.substring(0, filename.lastIndexOf('.'));
}

What you are doing wrong is. Whenever the orientation changes it gets the value again from extras which is null after the rotation change and it passes the same value to it. That's why you are getting the exception. try this hope it will help you.

edited Nov 17 '17 at 08:05

answered Nov 17 '17 at 07:38

Umair

6,366
15
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50

I get null pointer at `displayFileName.setText(savedText);` when doing this? – ClassA Nov 17 '17 at 07:46
@ClassA are you using this answer before or after this line ? displayFileName = (TextView) findViewById(R.id.displayFileName); – Umair Nov 17 '17 at 07:48
after `displayFileName = (TextView) findViewById(R.id.displayFileName);` – ClassA Nov 17 '17 at 07:49
Ok you are right there. Try debugging your code and see if the value is actually being saved in onSavedInstance state ? – Umair Nov 17 '17 at 07:50
How can I do that? I'm know that `nameWitoutExtention` is not empty and returns correct string. – ClassA Nov 17 '17 at 07:58
Ok I have tested by using a `Toast` inside `if(savedInstanceState != null){` and the file name gets toasted. – ClassA Nov 17 '17 at 08:01
Ok try this displayFileName.setText(savedText+""); – Umair Nov 17 '17 at 08:04
In your if(savedInstanceState) – Umair Nov 17 '17 at 08:04
Nope, still the same. – ClassA Nov 17 '17 at 08:07
@ClassA post your exception please. – Umair Nov 17 '17 at 08:11
@ClassA bro now there are two possibilities 1) you are passing wrong id to your textview. 2) your charSequence is null.or it is not taking the correct value. Try using String instead of CharSeq – Umair Nov 17 '17 at 08:25
OMW I was so stupid, I'm so sorry for wasting your time, the problem was that in my layout-land did not have the `TextView`, but still your answer helped me achieve this, thank you. – ClassA Nov 17 '17 at 08:38
Hahhahaha I am glad that I could be of help. happy coding ;-) – Umair Nov 17 '17 at 08:56

Saving and restoring text when rotating

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