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>