Question

Ok so I am working on an android app and I have implanted spinners… I have a total of four spinners and I have learned that if the spinner reads the options from the strings it has a defined number for the selection(i.e the first option is “0” next is “1” and so on)

I have the following code for the spinner

        Spinner a = (Spinner) findViewById(R.id.spinner1);
    a.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

        @Override
        public void onItemSelected(AdapterView adapter, View v, int a,
                long lng) {
            // do something here
            Toast.makeText(adapter.getContext(), "You selected: " + a,
                    Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onNothingSelected(AdapterView arg0) {
            // do something else
        }
    });

and another one but with the int “b”

but later on in the same class I want to use some maths to get e=a,b (i.e if a=6 and b=5 e=65, or a=4 and b=3 e=43)
This is easily done by executing

int e=a*10+b;

The problem is I want to display this when you press a button, so I have the following code

public void Calc(View v) {
    int e = a * 10 + b;
    Toast.makeText(this, "Value: " + e, Toast.LENGTH_LONG).show();
}

but results in the error “”a” & “b” cannot be resolved to a variable”
why is this and how can I create a button that will be able to read these variables?

Answer 1

It’s a matter of scope, since you declared a in a method, it is not accesible outside of the method. Declare the spinner as class members, and only assign it in the method:

class scope:

Spinner a;

In the method:

a = (Spinner) findViewById(R.id.spinner1);

Then:

public void Calc(View v) {
    int itemA, itemB;
    itemA = a.getSelectedItemPosition();
    itemB = b.getSelectedItemPosition();
    int e = itemA * 10 + itemB;
    Toast.makeText(this, "Value: " + e, Toast.LENGTH_LONG).show();
}