2

我对 android 有点陌生,我正在尝试使用 Jsoup 从网站检索一些数据。这是我在 Java 项目中使用的确切代码,它有效。但是当我将它转移到 Android 并将“println”更改为“setText()”时,应用程序“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);}}

这是 LogCat 跟踪:

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

我还不知道如何使用 AsyncTask,但从我在 Jsoup 食谱中看到的内容来看,我不需要任何 thred 来使其工作。

4

2 回答 2

0

试试这个代码:

Document doc = Jsoup.connect("http://example.com/").get();
Elements divs = doc.select("div#test");
for(Element div : divs)
    System.out.println(div.text());
于 2012-11-17T08:39:07.863 回答
0

你的代码对我有用,我可以在 TextView 中打印数据。

你得到 NullPointer 因为你的 findViewById 返回 null 因为你没有正确设置 setContentView ..,。

setContentView(R.layout.your_activity_xml);
于 2012-11-17T17:54:24.240 回答