使用Spinner实现下拉列表

一、实现下拉列表

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.AndroidCharacter;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener{

    private TextView textView;
    private Spinner spinner;
    private List<String>list;
    private ArrayAdapter<String>adapter;

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

        textView = (TextView) findViewById(R.id.textView);
        spinner = (Spinner) findViewById(R.id.spinner);
        //1、设置数据源
        list = new ArrayList<String>();
        list.add("上海");
        list.add("北京");
        list.add("广州");
        list.add("深圳");

        //2、新建ArrayAdapter（数组适配器）
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item,list);
        //3、adapter设置一个下拉列表样式
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        //4、spinner加载适配器
        spinner.setAdapter(adapter);
        //5、spinner设置监听器
        spinner.setOnItemSelectedListener(this);
    }

    @Override
    public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
        //通过adapter获取当前选择
        String cityName = adapter.getItem(i);
//        String cityName = list.get(i);
        textView.setText("您选择的城市是："+cityName);
    }

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

    }
}