<Spinner         android:id="@+id/mySpinner"         android:layout_height="wrap_content"         android:layout_width="fill_parent"         />

package com.example.spinner; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.widget.AdapterView; import android.widget.AdapterView.OnItemSelectedListener; import android.widget.ArrayAdapter; import android.widget.Spinner; import android.widget.Toast; public class MainActivity extends Activity {  private Spinner spinner;    @Override  protected void onCreate(Bundle savedInstanceState) {   super.onCreate(savedInstanceState);   setContentView(R.layout.activity_main);   spinner = (Spinner)this.findViewById(R.id.mySpinner);   //设置数据源   String[] mydata = {"北京", "上海","广东","广西"};   //声明一个ArrayAdapter，并将数据源与之关联起来   ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item,mydata);   //设置弹出下拉列表的风格   adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);   //将arrayAdapter对象添加进Spinner去   spinner.setAdapter(adapter);   //添加监听器   spinner.setOnItemSelectedListener(new OnItemSelectedListener() {    @Override    public void onItemSelected(AdapterView<?> arg0, View arg1,      int arg2, long arg3) {     Toast.makeText(MainActivity.this, "选择了：" + arg2, Toast.LENGTH_SHORT).show();    }    @Override    public void onNothingSelected(AdapterView<?> arg0) {     // TODO Auto-generated method stub    }   });  } }