Android的下拉式

package android.demo.spinner;import android.app.Activity;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.*;import android.widget.AdapterView.OnItemClickListener;import android.os.Bundle;public class Spinner_Activity extends Activity {    /** Called when the activity is first created. */private static final String[] m_Countries ={"111","222","333"};private TextView m_TextView;private Spinner m_Spinner;private String TAG;private ArrayAdapter<String> adapter;    @Override    public void onCreate(Bundle savedInstanceState)     {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);                m_Spinner = (Spinner) findViewById(R.id.Spinner1);        m_TextView= (TextView)findViewById(R.id.TextView1);        adapter= new ArrayAdapter<String>( this,android.R.layout.simple_spinner_item,m_Countries);        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);                m_Spinner.setAdapter(adapter);        try{                m_Spinner.setOnItemSelectedListener (On_ItemSelected_Click);        }catch(Exception err)        {        Log.e(TAG, "error: " + err.toString());Toast.makeText(Spinner_Activity.this,err.toString(),Toast.LENGTH_LONG).show();        };            }    public Spinner.OnItemSelectedListener On_ItemSelected_Click=new Spinner.OnItemSelectedListener()    {@Overridepublic void onItemSelected(AdapterView<?> arg0, View arg1, int arg2,long arg3){// TODO Auto-generated method stubToast.makeText(Spinner_Activity.this, "您"+arg0.getSelectedItem().toString(), Toast.LENGTH_LONG).show(); }@Overridepublic void onNothingSelected(AdapterView<?> arg0){// TODO Auto-generated method stub}    };}