public class layout8 extends AppCompatActivity implements AdapterView.OnItemSelectedListener {
    private TextView tv7;
    private Spinner sp;
    private ArrayAdapter adapter;
    private List<String> list=new ArrayList<String>();
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout7);
        sp= (Spinner) findViewById(R.id.spinner_1);
        tv7= (TextView) findViewById(R.id.textview_7);
        adapter=new ArrayAdapter<String>(this,R.layout.support_simple_spinner_dropdown_item,list);
        adapter.setDropDownViewResource(R.layout.support_simple_spinner_dropdown_item);
        sp.setAdapter(adapter);
        list.add("北京");
        list.add("上海");
        sp.setOnItemSelectedListener(this);
    }

    @Override
    public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
        String city=(String) adapter.getItem(i);
        tv7.setText(city);
    }

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

    }
}