从另一个类Android Studio访问变量

Question

I'm new to android development and I'm wondering how this can be done. I have a class named ListDeadlines with variables such as

public ArrayList<String> arrayList;
public ArrayAdapter<String> adapter;
public EditText txtInput;

I want to be able to access these variables in a different class. I have tried it like this, however I get the fallowing error on my lst.txtInput lst.arrayList lst.adapter saying Variable 'lst' is accessed from within inner class, needs to be declared final. Anyone got any ideas on how to access variables in another class.

    ListDeadlines lst= new ListDeadlines();
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

    lst.txtInput=(EditText)findViewById(R.id.txtinput);
    Button btAdd=(Button)findViewById(R.id.btnAdd);
    btAdd.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String newItem = lst.txtInput.getText().toString();
           lst.arrayList.add(newItem);
            lst.adapter.notifyDataSetChanged();
            ;
        }
    });

Answer 1

What you're trying to do here is access the variable lst from within an anonymous inner class in the same scope as lst. The anonymous inner class is your new View.OnClickListener . The rules for doing this in Java require that you declare lst as final so that the inner class can be certain that lst will not change when it eventually executes. So, you can declare your lst like this:

final ListDeadlines lst= new ListDeadlines();

Or you can make lst a member of the enclosing class that contains the method where it's currently defined.