我對Android有點新,我試圖從一個網站使用Jsoup檢索一些數據。 這是我在Java項目中使用的確切代碼,它工作正常。但是,當我將其轉移到Android並將「println」更改爲「setText()」時,應用程序「意外停止」。Android應用程序使用jsoup庫意外停止
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);}}
這裏是logcat的痕跡:
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尚未但是從我在Jsoup食譜看見我應該不需要任何thred使它工作。
你能從LogCat發佈堆棧跟蹤嗎? – antew
考慮使用異步任務,Jsoup#connect將在UI線程上執行網絡連接,這可以暫停您的應用程序。如果將try-catch放在「簡單」線程中,由於TextView#setText調用,它可能會崩潰,因爲您不應該篡改除UI線程以外的任何其他線程上的視圖。 – Jens