Keep a Changed Textview even after closing the app

Question

Guys I’m making an application for financial management, spending control for college, is my first experience with android studio and the java language, but I’m already evolving enough, I need to keep changed Textview user balance, the same in Oncreate has a Method that brings from another Activity a value to be treated according to what the user informs in the case spent or won, works perfectly, but when recreates the solution I end up losing the balance, I would like help to keep the value of Textview even after it is closed. follows down the onCreate of my Acitivity where has the method and the Textview that I wish to maintain. protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_home); Toolbar Toolbar = (Toolbar) findViewById(R.id.Toolbar); txtSaldo=(TextView)findViewById(R.id.txtSaldo); setSupportActionBar(Toolbar); Intent Intent = getIntent(); Bundle Bundle = Intent.getExtras(); if(Bundle!=null) { String txt = Bundle.getString("txt"); String test=Bundle.getString("test");

           if(teste!=null) {
               if (teste.contains("+")) {
                   v2 = txt;
                   double vb = Double.parseDouble(v2);
                   v1 = txtSaldo.getText().toString();
                   double va = Double.parseDouble(v1);
                   double total = vb + va;
                   resultado = Double.toString(total);

                   txtSaldo.setText(resultado);

               } else {
                   v2 = txt;
                   double vb = Double.parseDouble(v2);
                   v1 = txtSaldo.getText().toString();
                   double va = Double.parseDouble(v1);
                   double total = va - vb;
                   resultado = Double.toString(total);
                   txtSaldo.setText(resultado);
               }
           }


    }


    smartTabLayout = findViewById(R.id.smartTabLayout);
    viewPager = findViewById(R.id.viewpager);
    FragmentPagerItemAdapter adapter = new FragmentPagerItemAdapter(
            getSupportFragmentManager(),
            FragmentPagerItems.with(this)
                    .add("Últimos lançamentos", ListaFragment.class)
                    .add("Histórico Mês", HistoricoFragment.class)
                    .add("Gráficos", GraficoFragment.class)
                    .create()
    );
    viewPager.setAdapter(adapter);
    smartTabLayout.setViewPager(viewPager);


} 

Answer 1

You can do this in various ways, the most viable is to create a Sqlite database, or save it in a Sharedpreferences type variable, which is widely used for session. As the Sqlite method is more complex and long you will do a search, to start can go on this link: https://www.devmedia.com.br/criando-um-crud-com-android-studio-e-sqlite/32815

And here I will demonstrate how to use sharedPrefs:

It is stated in the second way:

SharedPreferences pref = getSharedPreferences("info", MODE_PRIVATE);
SharedPreferences.Editor editor = pref.edit();
editor.putString("VALOR_TXT", seuedittext.getText().toString());
editor.commit();

And to rescue her just do the following:

SharedPreferences pref = getSharedPreferences("info", MODE_PRIVATE);
String algumaString = pref.getString("VALOR_TXT", "");