我有mainactivity和spinneractivity，我想从spinneractivity中获取选中的微调器项值到mainactivity中。我尝试将字符串声明为静态，也尝试使用getter，但没有成功。
我应该如何在@override方法之外获取值并将其放入另一个类中？获得价值的正确方法是什么？
主活动类

public class MainActivity extends AppCompatActivity {

    SpinnerActivity spinnerActivity = new SpinnerActivity();

    Spinner spinnerProvince;

    String selectedSpinnerProvince = spinnerActivity.inSpinnerSelectedProvince;
//    String selectedSpinnerProvince = SpinnerActivity.inSpinnerSelectedProvince;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        spinnerProvince = findViewById(R.id.spinnerProvince);

        populateSpinnerProvinces();

        spinnerProvince.setOnItemSelectedListener(spinnerActivity);

    }

    public void populateSpinnerProvinces() {
        ArrayAdapter<String> provincesAdapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_item, getResources().getStringArray(R.array.province));
        provincesAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinnerProvince.setAdapter(provincesAdapter);
    }
}

spinneractivity.class类

public class SpinnerActivity implements android.widget.AdapterView.OnItemSelectedListener {

    public String inSpinnerSelectedProvince;

//    public static String getInSpinnerSelectedProvince() {
//        return inSpinnerSelectedProvince;
//    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

        inSpinnerSelectedProvince = parent.getItemAtPosition(position).toString();

        Toast.makeText(parent.getContext(), parent.getItemAtPosition(position).toString(), Toast.LENGTH_SHORT).show();

    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {

    }
}

在spinner活动中，我还将使用if语句，我认为它应该是相同的，但是无论如何，我应该如何将“if语句”和“@override method”之外的值获取到另一个类中？

public class SpinnerActivity implements android.widget.AdapterView.OnItemSelectedListener {

    public String inSpinnerSelectedProvince;

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

        if (parent.getId() == R.id.spinnerProvince) {

            inSpinnerSelectedProvince = parent.getItemAtPosition(position).toString();
            Toast.makeText(parent.getContext(), parent.getItemAtPosition(position).toString(), Toast.LENGTH_SHORT).show();

        } else {// code here}

    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {

    }
}