我对Android有点新,我试图从一个网站使用Jsoup检索一些数据。 这是我在Java项目中使用的确切代码,它工作正常。但是,当我将其转移到Android并将“println”更改为“setText()”时,应用程序“意外停止”。Android应用程序使用jsoup库意外停止
package com.ex.myschoolapp;
import java.io.IOException;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.select.Elements;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.widget.TextView;
public class MainActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Document doc = null;
try {
doc = Jsoup.connect("http://moisilonesti.licee.edu.ro/concursuri.php").get();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Elements sElem = doc.select("div#olimpiade table tbody tr th");
String str = sElem.text();
TextView stv = (TextView) findViewById(R.id.textView2);
stv.setText(str);}}
这里是logcat的痕迹:
11-17 17:37:59.145: E/AndroidRuntime(23601): FATAL EXCEPTION: main
11-17 17:37:59.145: E/AndroidRuntime(23601): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.ex.myschoolapp/com.ex.myschoolapp.MainActivity}: java.lang.NullPointerException
11-17 17:37:59.145: E/AndroidRuntime(23601): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1659)
11-17 17:37:59.145: E/AndroidRuntime(23601): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1675)
11-17 17:37:59.145: E/AndroidRuntime(23601): at android.app.ActivityThread.access$1500(ActivityThread.java:121)
11-17 17:37:59.145: E/AndroidRuntime(23601): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:943)
11-17 17:37:59.145: E/AndroidRuntime(23601): at android.os.Handler.dispatchMessage(Handler.java:99)
11-17 17:37:59.145: E/AndroidRuntime(23601): at android.os.Looper.loop(Looper.java:123)
11-17 17:37:59.145: E/AndroidRuntime(23601): at android.app.ActivityThread.main(ActivityThread.java:3701)
11-17 17:37:59.145: E/AndroidRuntime(23601): at java.lang.reflect.Method.invokeNative(Native Method)
11-17 17:37:59.145: E/AndroidRuntime(23601): at java.lang.reflect.Method.invoke(Method.java:507)
11-17 17:37:59.145: E/AndroidRuntime(23601): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:862)
11-17 17:37:59.145: E/AndroidRuntime(23601): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:620)
11-17 17:37:59.145: E/AndroidRuntime(23601): at dalvik.system.NativeStart.main(Native Method)
11-17 17:37:59.145: E/AndroidRuntime(23601): Caused by: java.lang.NullPointerException
11-17 17:37:59.145: E/AndroidRuntime(23601): at com.ex.myschoolapp.MainActivity.onCreate(MainActivity.java:67)
11-17 17:37:59.145: E/AndroidRuntime(23601): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
11-17 17:37:59.145: E/AndroidRuntime(23601): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1623)
11-17 17:37:59.145: E/AndroidRuntime(23601): ... 11 more
我不知道如何使用的AsyncTask尚未但是从我在Jsoup食谱看见我应该不需要任何thred使它工作。
你能从LogCat发布堆栈跟踪吗? – antew
考虑使用异步任务,Jsoup#connect将在UI线程上执行网络连接,这可以暂停您的应用程序。如果将try-catch放在“简单”线程中,由于TextView#setText调用,它可能会崩溃,因为您不应该篡改除UI线程以外的任何其他线程上的视图。 – Jens