Java 应用程序仅适用于第一个输入，如果插入第二个输入，应用程序将崩溃

该应用程序按预期工作。输入股票符号，按下enter按钮，数据从yahoo webservice中提取并显示在屏幕上。但是，在显示第一个股票符号后，如果输入新的股票符号，应用程序将崩溃

MainActivity.java

package com.example.quickstockinfo;


import java.io.IOException; 
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URI;
import java.net.URISyntaxException;

 import org.apache.http.HttpResponse;
 import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParserFactory;



import android.app.Activity;  
import android.app.AlertDialog;
import android.content.Context;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.inputmethod.InputMethodManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TableRow;
import android.widget.TextView;

public class MainActivity extends Activity {

EditText stocksymbol;
String stocksymbolstring;

Button enterbutton;

TextView CompanyName;
TextView YearLow;
TextView YearHigh;
TextView DaysLow;
TextView DaysHigh;
TextView LastPrice;
TextView Change;
TextView DailyPriceRange;

// XML node keys
    static final String KEY_ITEM = "quote"; // parent node
    static final String KEY_NAME = "Name";
    static final String KEY_YEAR_LOW = "YearLow";
    static final String KEY_YEAR_HIGH = "YearHigh";
    static final String KEY_DAYS_LOW = "DaysLow";
    static final String KEY_DAYS_HIGH = "DaysHigh";
    static final String KEY_LAST_TRADE_PRICE = "LastTradePriceOnly";
    static final String KEY_CHANGE = "Change";
    static final String KEY_DAYS_RANGE = "DaysRange";

    // XML Data to Retrieve
    String name = "";
    String yearLow = "";
    String yearHigh = "";
    String daysLow = "";
    String daysHigh = "";
    String lastTradePriceOnly = "";
    String change = "";
    String daysRange = "";

    // Used to make the URL to call for XML data
    String yahooURLFirst = "http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20yahoo.finance.quote%20where%20symbol%20in%20(%22";
    String yahooURLSecond = "%22)&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys";

    // NEW STUFF

    // Holds values pulled from the XML document using XmlPullParser
    String[][] xmlPullParserArray = {{"AverageDailyVolume", "0"}, {"Change", "0"}, {"DaysLow", "0"},
            {"DaysHigh", "0"}, {"YearLow", "0"}, {"YearHigh", "0"},
            {"MarketCapitalization", "0"}, {"LastTradePriceOnly", "0"}, {"DaysRange", "0"},
            {"Name", "0"}, {"Symbol", "0"}, {"Volume", "0"},
            {"StockExchange", "0"}};

    int parserArrayIncrement = 0;

    // END OF NEW STUFF

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    stocksymbol = (EditText)findViewById(R.id.stocksymbol);

    enterbutton = (Button)findViewById(R.id.enterbutton);

    CompanyName = (TextView)findViewById(R.id.stockName);
    YearLow = (TextView)findViewById(R.id.YearLow);
    YearHigh = (TextView)findViewById(R.id.YearHigh);
    DaysLow = (TextView)findViewById(R.id.DaysLow);
    DaysHigh = (TextView)findViewById(R.id.DaysHigh);
    LastPrice = (TextView)findViewById(R.id.LastPrice);
    Change = (TextView)findViewById(R.id.Change);
    DailyPriceRange = (TextView)findViewById(R.id.DailyPriceRange);

    enterbutton.setOnClickListener(enterbuttonlistener);


}

public OnClickListener enterbuttonlistener = new OnClickListener(){

    public void onClick(View v) {

        if(stocksymbol.getText().length() > 0){


            stocksymbolstring = stocksymbol.getText().toString();

            stocksymbol.setText(""); // Clear EditText box

            // Force the keyboard to close
            InputMethodManager imm = (InputMethodManager)getSystemService(
                      Context.INPUT_METHOD_SERVICE);
                imm.hideSoftInputFromWindow(stocksymbol.getWindowToken(), 0);
        } else {

            // Create an alert dialog box
            AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);

            // Set alert title 
            builder.setTitle("invalid stock symbol");

            // Set the value for the positive reaction from the user
            // You can also set a listener to call when it is pressed
            builder.setPositiveButton("ok", null);

            // The message
            builder.setMessage("missing stock symbol");

            // Create the alert dialog and display it
            AlertDialog theAlertDialog = builder.create();
            theAlertDialog.show();



        }// end else


        // Create the YQL query
        final String yqlURL = yahooURLFirst + stocksymbolstring + yahooURLSecond;

        new MyAsyncTask().execute(yqlURL);

    } //end onClick view v


}; //end button click event



private class MyAsyncTask extends AsyncTask<String, String, String>{

    // String... arg0 is the same as String[] args
    protected String doInBackground(String... args) {

        // NEW STUFF

        try{

            Log.d("test","In XmlPullParser");

            // It is recommended to use the XmlPullParser because
            // it is faster and requires less memory then the DOM API

            // XmlPullParserFactory provides you with the ability to 
            // create pull parsers that parse XML documents

            XmlPullParserFactory factory = XmlPullParserFactory.newInstance();

            // Parser supports XML namespaces
              factory.setNamespaceAware(true);

              // Provides the methods needed to parse XML documents
              XmlPullParser parser = factory.newPullParser(); 

              // InputStreamReader converts bytes of data into a stream
              // of characters

              parser.setInput(new InputStreamReader(getUrlData(args[0])));  

              // Passes the parser and the first tag in the XML document
              // for processing

              beginDocument(parser,"query");

              // Get the currently targeted event type, which starts
              // as START_DOCUMENT

              int eventType = parser.getEventType();

              do{

                // Cycles through elements in the XML document while
                // neither a start or end tag are found

                  nextElement(parser);

                  // Switch to the next element

                  parser.next();

                  // Get the current event type

                  eventType = parser.getEventType();

                  // Check if a value was found between 2 tags

                  if(eventType == XmlPullParser.TEXT){

                      // Get the text from between the tags

                      String valueFromXML = parser.getText();

                      // Store it in an array with the corresponding tag
                      // value

                      xmlPullParserArray[parserArrayIncrement++][1] = valueFromXML;

                  }

              } while (eventType != XmlPullParser.END_DOCUMENT) ;  

        }

        catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (XmlPullParserException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (URISyntaxException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }  

        finally {
        }

        // END OF NEW STUFF

        return null;
    }

    // NEW STUFF

    public InputStream getUrlData(String url) throws URISyntaxException, 
    ClientProtocolException, IOException {

        // Used to get access to HTTP resources

        DefaultHttpClient client = new DefaultHttpClient();

        // Retrieves information from the URL

        HttpGet method = new HttpGet(new URI(url));

        // Gets a response from the client on whether the 
        // connection is stable

        HttpResponse res = client.execute(method);

        // An HTTPEntity may be returned using getEntity() which tells 
        // the system where the content is coming from

        return res.getEntity().getContent();
    }

    public final void beginDocument(XmlPullParser parser, String firstElementName) throws XmlPullParserException, IOException
    {
        int type;

        // next() advances to the next element in the XML
        // document being a starting or ending tag, or a value
        // or the END_DOCUMENT

        while ((type=parser.next()) != parser.START_TAG
                       && type != parser.END_DOCUMENT) {
                ;
        }

        // Throw an error if a start tag isn't found

        if (type != parser.START_TAG) {
            throw new XmlPullParserException("No start tag found");
        }

        // Verify that the tag passed in is the first tag in the XML
        // document

        if (!parser.getName().equals(firstElementName)) {
                throw new XmlPullParserException("Unexpected start tag: found " + parser.getName() +
                        ", expected " + firstElementName);
        }
    }

    public final void nextElement(XmlPullParser parser) throws XmlPullParserException, IOException
    {
        int type;

        // Cycles through elements in the XML document while
        // neither a start or end tag are found

        while ((type=parser.next()) != parser.START_TAG
                       && type != parser.END_DOCUMENT) {
                ;
        }
    }

    // END OF NEW STUFF

    // Changes the values for a bunch of TextViews on the GUI
    protected void onPostExecute(String result){

        CompanyName.setText(xmlPullParserArray[9][1]);
        YearLow.setText("Year Low: " + xmlPullParserArray[4][1]);
        YearHigh.setText("Year High: " + xmlPullParserArray[5][1]);
        DaysLow.setText("Days Low: " + xmlPullParserArray[2][1]);
        DaysHigh.setText("Days High: " + xmlPullParserArray[3][1]);
        LastPrice.setText("Last Price: " + xmlPullParserArray[7][1]);
        Change.setText("Change: " + xmlPullParserArray[1][1]);
        DailyPriceRange.setText("Daily Price Range: " + xmlPullParserArray[8][1]);

    }

}

}

package com.example.quickstockinfo；
导入java.io.IOException；
导入java.io.InputStream；
导入java.io.InputStreamReader；
导入java.net.URI；
导入java.net.URISyntaxException；
导入org.apache.http.HttpResponse；
导入org.apache.http.client.ClientProtocolException；
导入org.apache.http.client.methods.HttpGet；
导入org.apache.http.impl.client.DefaultHttpClient；
导入org.xmlpull.v1.XmlPullParser；
导入org.xmlpull.v1.XmlPullParserException；
导入org.xmlpull.v1.XmlPullParserFactory；
导入android.app.Activity；
导入android.app.AlertDialog；
导入android.content.Context；
导入android.content.Intent；
导入android.os.AsyncTask；
导入android.os.Bundle；
导入android.util.Log；
导入android.view.Menu；
导入android.view.MenuItem；
导入android.view.view；
导入android.view.view.OnClickListener；
导入android.view.inputmethod.InputMethodManager；
导入android.widget.Button；
导入android.widget.EditText；
导入android.widget.TableRow；
导入android.widget.TextView；
公共类MainActivity扩展了活动{
编辑文本符号；
字符串stocksymbolstring；
按钮输入按钮；
TextView公司名称；
TextView YearLow；
文本视图年高；
TextView DaysLow；
TextView DaysHigh；
TextView最新价格；
文本视图更改；
文本视图每日价格范围；
//XML节点密钥
静态最终字符串KEY\u ITEM=“quote”；//父节点
静态最终字符串键\u NAME=“NAME”；
静态最终字符串键\u YEAR\u LOW=“YearLow”；
静态最终字符串键\u YEAR\u HIGH=“YearHigh”；
静态最终字符串键\u DAYS\u LOW=“DaysLow”；
静态最终字符串键\u DAYS\u HIGH=“DaysHigh”；
静态最终字符串键\u LAST\u TRADE\u PRICE=“LastTradePriceOnly”；
静态最终字符串键\u CHANGE=“CHANGE”；
静态最终字符串键\u DAYS\u RANGE=“DaysRange”；
//要检索的XML数据
字符串名称=”；
字符串yearLow=“”；
字符串yearHigh=“”；
字符串daysLow=“”；
字符串daysHigh=“”；
字符串lastTradePriceOnly=“”；
字符串更改=”；
字符串daysRange=“”；
//用于生成用于调用XML数据的URL
字符串yahooURLFirst=”http://query.yahooapis.com/v1/public/yql?q=select%20*%20来自%20yahoo.finance.quote%20，其中%20symbol%20位于%20（%22）；
字符串yahooURLSecond=“%22）&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys”；
//新东西
//保存使用XmlPullParser从XML文档中提取的值
字符串[][]XmlPullParseRaray={{“AverageDailyVolume”，“0”}，{“Change”，“0”}，{“DaysLow”，“0”}，
{“DaysHigh”，“0”}，{“YearLow”，“0”}，{“YearHigh”，“0”}，
{“市值”、“0”}、{“LastTradePriceOnly”、“0”}、{“DaysRange”、“0”}，
{“名称”，“0”}，{“符号”，“0”}，{“卷”，“0”}，
{“证券交易所”，“0”}；
int parserayrayincrement=0；
//新事物的终结
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_main）；
stocksymbol=（EditText）findViewById（R.id.stocksymbol）；
enterbutton=（按钮）findViewById（R.id.enterbutton）；
CompanyName=（TextView）findViewById（R.id.stockName）；
YearLow=（TextView）findViewById（R.id.YearLow）；
YearHigh=（TextView）findViewById（R.id.YearHigh）；
DaysLow=（TextView）findViewById（R.id.DaysLow）；
DaysHigh=（TextView）findViewById（R.id.DaysHigh）；
LastPrice=（TextView）findViewById（R.id.LastPrice）；
Change=（TextView）findViewById（R.id.Change）；
DailyPriceRange=（TextView）findViewById（R.id.DailyPriceRange）；
setOnClickListener（enterbuttonlistener）；
}
public OnClickListener enterbuttonlistener=new OnClickListener（）{
公共void onClick（视图v）{
如果（stocksymbol.getText（）.length（）>0）{
stocksymbolstring=stocksymbol.getText（）.toString（）；
stocksymbol.setText（“”；//清除编辑文本框
//强制关闭键盘
InputMethodManager imm=（InputMethodManager）getSystemService(
上下文。输入方法（服务）；
imm.hideSoftInputFromWindow（stocksymbol.getWindowToken（），0）；
}否则{
//创建警报对话框
AlertDialog.Builder=新建AlertDialog.Builder（MainActivity.this）；
//设置警报标题
builder.setTitle（“无效库存符号”）；
//为用户的积极反应设置值
//您还可以将侦听器设置为在按下时调用
builder.setPositiveButton（“确定”，null）；
//信息
builder.setMessage（“缺少库存符号”）；
//创建警报对话框并显示它
AlertDialog theAlertDialog=builder.create（）；
theAlertDialog.show（）；
}//结束其他
//创建YQL查询
最后一个字符串YQURL=yahooURLFirst+stocksymbolstring+yahooURLSecond；
新建MyAsyncTask（）.execute（yqlURL）；
}//结束onClick视图v
}；//结束按钮单击事件
私有类MyAsyncTask扩展了AsyncTask{
//字符串…arg0与字符串[]args相同
受保护的字符串doInBackground（字符串…args）{
//新东西
试一试{
Log.d（“test”，“在XmlPullParser中”）；
//建议使用XmlPullParser，因为
//与domapi相比，它速度更快，所需内存更少
//XmlPullParserFactory为您提供了
//创建解析XML文档的拉式解析器
XmlPullParserFactory工厂=XmlPullParserFactory.newInstance（）；
//解析器支持XML名称空间
factory.setNamespaceAw
int parserArrayIncrement = 0;

protected String doInBackground(
    int parserArrayIncrement = 0;