Question

Is there a way to save everything so you don’t lose all data after a restart?

    bCalculate.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {
            // TODO Auto-generated method stub

            InputMethodManager inputManager = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);

            inputManager.hideSoftInputFromWindow(getCurrentFocus()
                    .getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);

            int error = 0;
            int anzahlGraden = 0;
            double d1 = 0.0, d2 = 0.0, d3 = 0.0, d4 = 0.0, d5 = 0.0, d6 = 0.0, d7 = 0.0, d8 = 0.0, d9 = 0.0, d10 = 0.0;

            EditText Grade1r = (EditText) findViewById(R.id.Grade1r);
            String Grade1 = Grade1r.getText().toString();

            EditText Grade2r = (EditText) findViewById(R.id.Grade2r);
            String Grade2 = Grade2r.getText().toString();

            EditText Grade3r = (EditText) findViewById(R.id.Grade3r);
            String Grade3 = Grade3r.getText().toString();

            EditText Grade4r = (EditText) findViewById(R.id.Grade4r);
            String Grade4 = Grade4r.getText().toString();

            EditText Grade5r = (EditText) findViewById(R.id.Grade5r);
            String Grade5 = Grade5r.getText().toString();

            EditText Grade6r = (EditText) findViewById(R.id.Grade6r);
            String Grade6 = Grade6r.getText().toString();

            EditText Grade7r = (EditText) findViewById(R.id.Grade7r);
            String Grade7 = Grade7r.getText().toString();

            EditText Grade8r = (EditText) findViewById(R.id.Grade8r);
            String Grade8 = Grade8r.getText().toString();

            EditText Grade9r = (EditText) findViewById(R.id.Grade9r);
            String Grade9 = Grade9r.getText().toString();

            EditText Grade10r = (EditText) findViewById(R.id.Grade10r);
            String Grade10 = Grade10r.getText().toString();

            if (Grade1.equals("")) {
                error++;
            } else {
                d1 = Double.parseDouble(Grade1);
                anzahlGraden++;
            }

            if (Grade2.equals("")) {
                error++;
            } else {
                d2 = Double.parseDouble(Grade2);
                anzahlGraden++;
            }

            if (Grade3.equals("")) {
                error++;
            } else {
                d3 = Double.parseDouble(Grade3);
                anzahlGraden++;
            }

            if (Grade4.equals("")) {
                error++;
            } else {
                d4 = Double.parseDouble(Grade4);
                anzahlGraden++;
            }

            if (Grade5.equals("")) {
                error++;
            } else {
                d5 = Double.parseDouble(Grade5);
                anzahlGraden++;
            }

            if (Grade6.equals("")) {
                error++;
            } else {
                d6 = Double.parseDouble(Grade6);
                anzahlGraden++;
            }

            if (Grade7.equals("")) {
                error++;
            } else {
                d7 = Double.parseDouble(Grade7);
                anzahlGraden++;
            }

            if (Grade8.equals("")) {
                error++;
            } else {
                d8 = Double.parseDouble(Grade8);
                anzahlGraden++;
            }

            if (Grade9.equals("")) {
                error++;
            } else {
                d9 = Double.parseDouble(Grade9);
                anzahlGraden++;
            }

            if (Grade10.equals("")) {
                error++;
            } else {
                d10 = Double.parseDouble(Grade10);
                anzahlGraden++;
            }

            if (error > 8) {
                display.setText("Please enter more then 2 grades.");
            } else {

                double gesamt = d1 + d2 + d3 + d4 + d5 + d6 + d7 + d8 + d9
                        + d10;

                double resultat = gesamt / anzahlGraden;

                display.setText("Your average is " + resultat);


            }





        }

    });

}

this app calculates your average for schoolgrades…

I want to keep all edittext inputs… so the user can evertime come back and add new data…

Answer 1

A combination of onPause, onCreate, and SharedPreferences is what you want:

 private SharedPreferences mPrefs;
 private EditText grade1r;

 protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);

     mPrefs = getSharedPreferences();

     String rememberedText1 = mPrefs.getString("grade1r", "");
     grade1r = (EditText) findViewById(R.id.Grade1r);
     grade1r.setText(rememberedText1);
 }

 protected void onPause() {
     super.onPause();

     SharedPreferences.Editor ed = mPrefs.edit();
     ed.putString("grade1r", grade1r.getText().toString());
     ed.commit();
 }

This is using the Activity lifecycle to populate and save your edittexts view information.

You may want to clear the preference at some point but thats up to you.

References:

Activity lifecycle

Saving State