force close when editing TextView from different class

Question

I want to edit TextView in Class A with data from spinner from Class B

Class A

TextView tvv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.ClassA);
tvv = findViewById(R.id.tv_sel1);

public TextView getTextView() {    
        TextView tv = tvv;
            return tv;
       }
}

Class B

select1.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
                @Override

    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                Toast.makeText(getApplicationContext(),
"Select 1 - "    +parent.getSelectedItem().toString(),
Toast.LENGTH_LONG).show();

                ClassA txt = new ClassA();
                TextView tv = txt.getTextView();
                tv.setText(parent.getSelectedItem().toString());

            }

when I run "debug" whit prints, app force close on

tv.setText(parent.getSelectedItem().toString());

So I put the text in wrong format or is there some other mistake?

you will need to pass this data with a putextra from class b to class a, then get that value and simply put it inside your setText — Gastón Saillén, Apr 19 '18 at 15:04
yet another ... where `ClassA.onCreate` is called? nowhere ... which obviously will cause NPE when you would like to use `getTextView` ... please learn some android basics: do not create `Activity/Service/Application` derived class by yourself with operator `new` — Selvin, Apr 19 '18 at 15:05

Daan Seuntjens · Accepted Answer · 2018-04-19T19:48:02.253

0

In class A u should set a method to set the text on the textvieuw:

Class A:

public void setText(String text) {    
    tvv.setText(text);
   }

Class B:

ClassA.setText(parent.getSelectedItem().toString());

edited Apr 19 '18 at 19:48

answered Apr 19 '18 at 15:18

Daan Seuntjens

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this is working with some edit, I am using void now because i have nothing to return or should I? – Filip Barák Apr 19 '18 at 15:39
yeah you should, that's the right usage for void, edited my answer for that so other people don't get mistaken by that – Daan Seuntjens Apr 19 '18 at 19:47

force close when editing TextView from different class

1 Answers1