android Spinner的使用

package com.example.spinnertest;import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.TextView;import com.example.spinnertest.R;public class MainActivity extends Activity {
private Spinner myS;
private List<String> datas=new ArrayList<String>();
private MySpinnerAdapter sAdapter;
private String value;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myS = (Spinner)findViewById(R.id.spinnerS);
initData();
sAdapter = new MySpinnerAdapter(this,datas);
myS.setAdapter(sAdapter);
refreshShowView();
myS.setOnItemSelectedListener(new OnItemSelectedListener() { @Override
public void onItemSelected(AdapterView<?> arg0, View arg1,
int arg2, long arg3) {
// TODO Auto-generated method stub
value = sAdapter.getItem(arg2);
} @Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub }
});
} private void initData() {
// TODO Auto-generated method stub
datas.add("a");
datas.add("b");
datas.add("c");
datas.add("d");
datas.add("e");
datas.add("f");
value = datas.get(4);
} @Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
} class MySpinnerAdapter extends ArrayAdapter<String> { private List<String> mList;
private Context mContext;
class ViewHolder {
public TextView spinnerTv;
public ViewHolder(View v){
spinnerTv = (TextView)v.findViewById(R.id.spinner_tv);
}
}
public MySpinnerAdapter(Context context, List<String> list) {
super(context,R.layout.spinner_item,R.id.spinner_tv, list);
// TODO Auto-generated constructor stub
setData(list);
mContext = context;
}
public void setData(List<String> list){
mList = list;
notifyDataSetChanged();
} @Override
public int getCount() {
// TODO Auto-generated method stub
if(mList==null){
return 0;
}
return mList.size();
} @Override
public String getItem(int position) {
// TODO Auto-generated method stub
if(mList==null){
return null;
}
return mList.get(position);
} @Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
} @Override
public View getDropDownView(int position, View convertView, ViewGroup parent)
{
ViewHolder holder = null;
if(convertView==null){
convertView = LayoutInflater.from(mContext).inflate(
R.layout.spinner_item, null);
holder= new ViewHolder(convertView);
convertView.setTag(holder);
}else{
holder = (ViewHolder)convertView.getTag();
}
String myListItem = mList.get(position);
holder.spinnerTv.setText(myListItem);
return convertView;
} } private void refreshShowView(){
if(!TextUtils.isEmpty(value)){
int i = 0;
for(String item:datas){
if(value.equals(item)){
break;
}
i++;
}
if(i==datas.size()){
i = datas.size()-1;
}
myS.setSelection(i);
}
};}

<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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:orientation="horizontal"
android:gravity="center_vertical"
tools:context=".MainActivity" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="标题"/>
<Spinner
android:id="@+id/spinnerS"
android:layout_width="0dp"
android:layout_weight="1"
android:layout_height="wrap_content"/></LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:paddingTop="10dp"
android:paddingBottom="10dp"
android:id="@+id/spinner_tv"/>
</RelativeLayout>