AsyncTask onPreExecute 未被调用
由于某种原因,onPreExecute 没有被调用。代码:
protected void onPreExcecute() {
hook.createDialog(ticker);
}
整个类:
package com.evandarwin.finance;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import android.content.Context;
import android.os.AsyncTask;
import android.widget.Toast;
public class GetTicker extends AsyncTask<String, Integer, String>{
private Context ctx;
private String ticker;
private SimpleFinanceActivity hook;
public GetTicker(Context ctx, String ticker, SimpleFinanceActivity hook) {
this.ctx = ctx;
this.ticker = ticker.toUpperCase();
this.hook = hook;
}
protected void onPreExcecute() {
hook.createDialog(ticker);
}
@SuppressWarnings("unused")
@Override
protected String doInBackground(String... params) {
try {
URL url = new URL("http://finance.yahoo.com/d/quotes.csv?s="+ticker+"&f=a");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
urlConnection.connect();
InputStream is = urlConnection.getInputStream();
StringBuffer str = new StringBuffer();
int bufferLength = 0; //used to store a temporary size of the buffer
byte[] stream = new byte[1024];
while ( (bufferLength = is.read(stream)) > 0 ) {
str.append(stream);
}
return str.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
}
return null;
}
protected void onPostExecute(String result) {
hook.destroyDialog();
Toast.makeText(ctx, result, Toast.LENGTH_LONG).show();
}
}
这给了我一个 NullPointerException,我知道我以前遇到过这个问题,但我不记得我做了什么来解决它。请帮忙! :P
For some reason the onPreExecute isn't being called. Code:
protected void onPreExcecute() {
hook.createDialog(ticker);
}
Entire class:
package com.evandarwin.finance;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import android.content.Context;
import android.os.AsyncTask;
import android.widget.Toast;
public class GetTicker extends AsyncTask<String, Integer, String>{
private Context ctx;
private String ticker;
private SimpleFinanceActivity hook;
public GetTicker(Context ctx, String ticker, SimpleFinanceActivity hook) {
this.ctx = ctx;
this.ticker = ticker.toUpperCase();
this.hook = hook;
}
protected void onPreExcecute() {
hook.createDialog(ticker);
}
@SuppressWarnings("unused")
@Override
protected String doInBackground(String... params) {
try {
URL url = new URL("http://finance.yahoo.com/d/quotes.csv?s="+ticker+"&f=a");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
urlConnection.connect();
InputStream is = urlConnection.getInputStream();
StringBuffer str = new StringBuffer();
int bufferLength = 0; //used to store a temporary size of the buffer
byte[] stream = new byte[1024];
while ( (bufferLength = is.read(stream)) > 0 ) {
str.append(stream);
}
return str.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
}
return null;
}
protected void onPostExecute(String result) {
hook.destroyDialog();
Toast.makeText(ctx, result, Toast.LENGTH_LONG).show();
}
}
This is giving me a NullPointerException, I know I've had this problem before but I don't remember what I did to fix it. Please help! :P
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@Override
在 Eclipse 中导致问题(以及该方法未被调用的原因)的原因是您输入了错误。您将其称为
onPreExcecute
(请注意“x”后面的“c”不应该出现)。将其更正为onPreExecute
并使用@Override
来实现。The reason the
@Override
is causing a problem in Eclipse (and the reason the method isn't being called) is that you have made a typing error.You are calling it
onPreExcecute
(note the 'c' after the 'x' shouldn't be there). Correct it to beonPreExecute
and use@Override
for that.