Android studio problem continue increasing counter

Question

I am tring to make the part of a game where when you press the fab icon, a TextView, increase numbers. It starts from zero and increased by one. I tried to save the number, in order to find it the next time, start the app and continue to increase it. I am new at saving and I searched it a little bit.

I wrote a code, where keeps the number when I close it and reopen it, but when I push the fab icon, it starts from the beginning and not from the number I have saved. Perhaps I didn't understand very well the save code how it works. Can anyone help me? Thank you!!

My code in MainActivity is:

int newAge;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        final TextView age  = (TextView) findViewById(R.id.age);

        FloatingActionButton fab = findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                newAge++;
                age.setText(String.valueOf(newAge));
            }
        });

        //getting preferences
        SharedPreferences prefs = this.getSharedPreferences("myPrefsKey", Context.MODE_PRIVATE);
        int savedAge = prefs.getInt("key", 0); //0 is the default value
        age.setText(String.valueOf(savedAge));

    }
    @Override
    protected void onStop(){
        super.onStop();
        SharedPreferences prefs = this.getSharedPreferences("myPrefsKey", Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = prefs.edit();
        editor.putInt("key", newAge);
        editor.commit();
    }

Answer 1

You have to apply savedAge to newAge, because once you load your age from the SharedPreferences, you only apply the laoded age to the TextView and if you click on the button, the TextView will display 1 instead of your saved value.

int newAge;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    final TextView age  = (TextView) findViewById(R.id.age);

    //getting preferences
    SharedPreferences prefs = this.getSharedPreferences("myPrefsKey", Context.MODE_PRIVATE);
    int savedAge = prefs.getInt("key", 0); //0 is the default value
    age.setText(String.valueOf(savedAge));
    newAge = savedAge; //set the age value, to further increase it by a button click

    FloatingActionButton fab = findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            newAge++;
            age.setText(String.valueOf(newAge));
        }
    });



}
@Override
protected void onStop(){
    super.onStop();
    SharedPreferences prefs = this.getSharedPreferences("myPrefsKey", Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = prefs.edit();
    editor.putInt("key", newAge);
    editor.commit();
}

Try to read through this, to get a better understanding of SharedPreferences in Android.