我正在使用下面的代码。它在Android Studio中出错。你能帮忙吗？根据我的理解，args [0]没有填充某些值。这是为什么？如果args [0]没有为此选择任何其他任何值。
import android.app.Activity;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.provider.DocumentsContract;
import android.renderscript.Element;
import android.util.Log;
import android.widget.TextView;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
import java.io.IOException;
import java.io.InputStream;
import java.lang.annotation.ElementType;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
public class StockInfoActivity extends Activity{
private static final String TAG="StockQoute";
static final String KEY_ITEM="quote";
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_CHANGE="Change";
static final String KEY_LAST_TRADE="LastTradePriceOnly";
static final String KEY_DAYS_CHANGE="DaysRange";
TextView companyNameView;
TextView yearLowView ;
TextView yearHighView ;
TextView daysLowView ;
TextView daysHighView ;
TextView LastPriceView ;
TextView changeView ;
TextView dailyPriceRangeView;
String name="";
String yearLow="";
String yearHigh="";
String daysLow="";
String daysHigh="";
String lastTradePrice="";
String change="";
String daysRange="";
String yahooURLFirst="https://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20yahoo.finance.quote%20where%20symbol%20in%20(%22";
String yahooURLSecond="%22)&diagnostics=true&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys";
protected void onCreate (Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.get_stock_qoute);
Intent intent=getIntent();
String stockSymbol=intent.getStringExtra(MainActivity.STOCK_SYMBOL);
companyNameView =(TextView)findViewById(R.id.companyNameView);
yearLowView =(TextView)findViewById(R.id.yearLow);
yearHighView =(TextView)findViewById(R.id.yearHigh);
daysLowView =(TextView)findViewById(R.id.daysLow);
daysHighView =(TextView)findViewById(R.id.daysHigh);
LastPriceView =(TextView)findViewById(R.id.lastPrice);
changeView =(TextView)findViewById(R.id.change);
dailyPriceRangeView =(TextView)findViewById(R.id.dailyPriceRange);
//Log.d(TAG, "Before URL creation" + stockSymbol);
final String yqlURL=yahooURLFirst+stockSymbol+yahooURLSecond;
//Log.d(TAG, "Before URL creation" + yqlURL);
new MyAsyncTask().execute();
}
private class MyAsyncTask extends AsyncTask<String,String,String>{
protected String doInBackground(String... args) {
try{
String newstr=args[0];
Log.d("Sync",newstr);
URL url= new URL(args[0]);
//Log.d("Sync1","We are here");
URLConnection conn=url.openConnection();
HttpURLConnection httpconn=(HttpURLConnection)conn;
int responseCode=httpconn.getResponseCode();
if(responseCode==HttpURLConnection.HTTP_OK){
InputStream in=httpconn.getInputStream();
DocumentBuilderFactory dbf= DocumentBuilderFactory.newInstance();
DocumentBuilder db=dbf.newDocumentBuilder();
Document dom=db.parse(in);
org.w3c.dom.Element docEl= (org.w3c.dom.Element) dom.getDocumentElement();
NodeList nl = docEl.getElementsByTagName("qoute");
Log.d("Sync3","We are here");
if(nl!=null && nl.getLength() > 0){
for(int i=0;i<=nl.getLength();i++){
StockInfo theStock=getStockInfo(docEl);
name=theStock.getName();
yearLow=theStock.getYearLow();
yearHigh=theStock.getYearHigh();
daysLow=theStock.getDaysLow();
daysHigh=theStock.getDaysHigh();
lastTradePrice=theStock.getLastTradePriceonly();
change=theStock.getChange();
daysRange=theStock.getDaysRange();
}
}
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ParserConfigurationException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
}
finally { }
return null;
}
protected void onPostExecute(String result){
companyNameView.setText(name);
yearHighView.setText("Year High: " +yearHigh);
yearLowView.setText("Year Low: "+yearLow);
daysHighView.setText("Days High: "+daysHigh);
daysLowView.setText("Days Low:"+ daysLow );
LastPriceView.setText("Last Price"+ lastTradePrice);
changeView.setText("Change: "+change);
dailyPriceRangeView.setText("Daily Price Range: "+daysRange) ;
}
private StockInfo getStockInfo(org.w3c.dom.Element entry){
String stockName=getTextValue(entry,"Name");
String stockYearLow=getTextValue(entry,"YearLow");
String stockYearHigh=getTextValue(entry,"YearHigh");
String stockDaysLow=getTextValue(entry,"DaysLow");
String stockDaysHigh=getTextValue(entry,"DaysHigh");
String stockLastTradePrice=getTextValue(entry,"LastTradePriceOnly");
String stockChange=getTextValue(entry,"Change");
String stockDaysRange=getTextValue(entry,"DaysRange");
StockInfo theStock=new StockInfo(stockDaysLow
,stockDaysHigh ,stockYearLow ,stockYearHigh ,stockName,stockLastTradePrice ,stockChange ,stockDaysRange);
return theStock;
}
private String getTextValue(org.w3c.dom.Element Entry, String tagName)
{
String tagValueToReturn=null;
NodeList nl=Entry.getElementsByTagName(tagName);
if(nl!=null && nl.getLength() > 0){
org.w3c.dom.Element ele=(org.w3c.dom.Element)nl.item(0);
tagValueToReturn=ele.getFirstChild().getNodeValue();
}
return tagValueToReturn;
}
}
}
低于错误
FATAL EXCEPTION: AsyncTask #1
Process: com.shravan.stockinfo, PID: 2188
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:304)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
at java.util.concurrent.FutureTask.run(FutureTask.java:242)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
Caused by: java.lang.ArrayIndexOutOfBoundsException: length=0; index=1
at com.shravan.stockinfo.StockInfoActivity$MyAsyncTask.doInBackground(StockInfoActivity.java:89)
at com.shravan.stockinfo.StockInfoActivity$MyAsyncTask.doInBackground(StockInfoActivity.java:85)
at android.os.AsyncTask$2.call(AsyncTask.java:292)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:818)
答案 0 :(得分：3)
您正在运行AsyncTask new MyAsyncTask().execute();，这意味着您没有向其传递任何参数。
但在doInBackground方法中，您尝试获取String newstr=args[0];的值，但args数组的长度为0。
你需要启动AsycTask这样的东西
new MyAsyncTask().execute(yqlURL);
答案 1 :(得分：1)
您没有将参数发送到异步任务，因此当您执行args[0]时它找不到任何内容，请记住发送这样的参数mytask.execute(params);
答案 2 :(得分：0)
new MyAsyncTask().execute();
protected String doInBackground(String... args) {
try{
String newstr=args[0];
Log.d("Sync",newstr);
URL url= new URL(args[0]);
....
}
仍在尝试阅读String newstr=args[0];，直接通过
new MyAsyncTask(yourString).execute();
答案 3 :(得分：0)