Spinner

2017.10.03晚上
这次学了Spinner下拉条，
arrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
这是下拉菜单条的默认样式，
setOnItemSelectedListener
这是需要添加的每一项的监听

public class MainActivity extends AppCompatActivity {
        private Spinner spinner;
        private TextView textView;
        private ArrayAdapter arrayAdapter;
        private List<String>data_list;


    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        spinner=(Spinner)findViewById(R.id.spinner);
        textView=(TextView) findViewById(R.id.textView);
        textView.setText("您选择的城市是：");
        data_list=new ArrayList<String>();
        data_list.add("北京");
        data_list.add("上海");
        data_list.add("广州");
        data_list.add("深圳");
        arrayAdapter=new ArrayAdapter(this,android.R.layout.simple_list_item_1,data_list);
        arrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(arrayAdapter);
        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
                String cityName=data_list.get(i);
                textView.setText("您选择的城市是："+cityName);
            }

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

            }
        });
    }
}