Android使用 Spinner控件实现下拉框功能

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:app="http://schemas.android.com/apk/res-auto"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 tools:context=".MainActivity">
 <TextView
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:id="@+id/spinner_textview"/>
 <Spinner
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:id="@+id/spinner1"></Spinner>
</LinearLayout>

public class MainActivity extends AppCompatActivity {
 private List<String> teamList;
 private TextView textView;
 private Spinner spinner1;
 private ArrayAdapter<String> arrayAdapter;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  initView();
  //设置下拉列表的风格
  arrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
  //将adapter 添加到spinner中
  spinner1.setAdapter(arrayAdapter);
  //设置点击事件
  spinner1.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
   @Override
   public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
    textView.setText(teamList.get(i));
   }
   @Override
   public void onNothingSelected(AdapterView<?> adapterView) {
   }
  });
 }
 public void initView(){
  teamList = new ArrayList<>();
  initList();
  textView = findViewById(R.id.spinner_textview);
  spinner1 = findViewById(R.id.spinner1);
  arrayAdapter = new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_spinner_item,teamList);
 }
 public void initList(){
  teamList.add("罗马");
  teamList.add("那不勒斯");
  teamList.add("国际米兰");
  teamList.add("AC米兰");
 }
}

<LinearLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical">
 <!--定义一个Spinner组件，指定显示该Spinner组件的数组-->
 <Spinner
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:entries="@array/books"
  android:popupBackground="#66ccff"
  android:dropDownWidth="230dp"
  ></Spinner>
 <Spinner
  android:id="@+id/spinner"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  ></Spinner>
</LinearLayout>
public class MainActivity extends AppCompatActivity {
 Spinner spinner;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  //获取界面布局文件的Spinner组件
  spinner= (Spinner) findViewById(R.id.spinner);
  String[] arr={"孙悟空","猪八戒","唐僧"};
  //创建ArrayAdapter对象
  ArrayAdapter<String> adapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_multiple_choice,arr);
  spinner.setAdapter(adapter);
 }
}