android Spinner的使用

首先是MainActivity

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);
        }
    };

}

然后是activity_main.xml

<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>

然后是spinner_item:

<?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>