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当我试图运行我的程序应用程序崩溃时，我做错了什么我无法理解，我不知道该怎么办，请帮助我。

这是我到目前为止所做的代码，

MainActivity.java

public class MainActivity extends ListActivity {

// All static variables
static final String URL = "http://www.androidpeople.com/wp-content/uploads/2010/06/example.xml";
// XML node keys
static final String KEY_ITEM = "item"; // parent node
//static final String KEY_ID = "id";
static final String KEY_NAME = "name";
static final String KEY_WEBSITE_CATEGORY = "website";
//static final String KEY_DESC = "description";

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    ArrayList<HashMap<String, String>> menuItems = new ArrayList<HashMap<String, String>>();

    XMLParser parser = new XMLParser();
    String xml = parser.getXmlFromUrl(URL); // getting XML
    Document doc = parser.getDomElement(xml); // getting DOM element

    NodeList nl = doc.getElementsByTagName(KEY_ITEM);
    // looping through all item nodes <item>
    for (int i = 0; i < nl.getLength(); i++) {
        // creating new HashMap
        HashMap<String, String> map = new HashMap<String, String>();
        Element e = (Element) nl.item(i);
        // adding each child node to HashMap key => value
        //map.put(KEY_ID, parser.getValue(e, KEY_ID));
        map.put(KEY_NAME, parser.getValue(e, KEY_NAME));
        map.put(KEY_WEBSITE_CATEGORY, "Rs." + parser.getValue(e,KEY_WEBSITE_CATEGORY));
        //map.put(KEY_DESC, parser.getValue(e, KEY_DESC));

        // adding HashList to ArrayList
        menuItems.add(map);
    }
}
}

XMLParser.java

public class XMLParser {

// constructor
public XMLParser() {

}

/**
 * Getting XML from URL making HTTP request
 * @param url string
 * */
public String getXmlFromUrl(String url) {
    String xml = null;

    try {
        // defaultHttpClient
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url);

        HttpResponse httpResponse = httpClient.execute(httpPost);
        HttpEntity httpEntity = httpResponse.getEntity();
        xml = EntityUtils.toString(httpEntity);

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    // return XML
    return xml;
}

/**
 * Getting XML DOM element
 * @param XML string
 * */
public Document getDomElement(String xml){
    Document doc = null;
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    try {

        DocumentBuilder db = dbf.newDocumentBuilder();

        InputSource is = new InputSource();
        is.setCharacterStream(new StringReader(xml));
        doc = db.parse(is);

    } catch (ParserConfigurationException e) {
        Log.e("Error: ", e.getMessage());
        return null;
    } catch (SAXException e) {
        Log.e("Error: ", e.getMessage());
        return null;
    } catch (IOException e) {
        Log.e("Error: ", e.getMessage());
        return null;
    }

    return doc;
}

public final String getElementValue( Node elem ) {
    Node child;
    if( elem != null){
        if (elem.hasChildNodes()){
            for( child = elem.getFirstChild(); child != null; child = child.getNextSibling() ){
                if( child.getNodeType() == Node.TEXT_NODE  ){
                    return child.getNodeValue();
                }
            }
        }
    }
    return "";
}

public String getValue(Element item, String str) {
    NodeList n = item.getElementsByTagName(str);
    return this.getElementValue(n.item(0));
}

}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.jszala.xmldemo"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="7"
    android:targetSdkVersion="16" />

<uses-permission android:name="android.permission.INTERNET" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.jszala.xmldemo.MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"
          android:orientation="vertical">

<ListView
    android:id="@android:id/list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/>

</LinearLayout>

LogCat 错误

FATAL EXCEPTION: main Unable to start activity ComponentInfo{com.jszala.xmldemo/com.jszala.xmldemo.MainActivity}: java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list'
4

1 回答 1

2

从文档中引用

ListActivity具有默认布局，由屏幕中央的单个全屏列表组成。但是，如果您愿意，您可以通过在 onCreate() 中使用 setContentView() 设置您自己的视图布局来自定义屏幕布局。为此，您自己的视图必须包含一个 ID 为“@android:id/list”的 ListView 对象（如果它在代码中，则为列表）

http://developer.android.com/reference/android/app/ListActivity.html

确保你有下面的列表

 android:id="@android:id/list"

你也有这个String xml = parser.getXmlFromUrl(URL)。您可能正在 ui 线程上运行与网络相关的操作。因此，如果您从服务器获取 xml，请使用thread或Asynctask

你需要把它 HttpResponse httpResponse = httpClient.execute(httpPost)放在一个threador里面Asynctask。

编辑：

public class MainActivity extends ListActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

}
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"
          android:orientation="vertical">

<ListView
    android:id="@android:id/list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/>

</LinearLayout>
于 2013-10-08T11:44:43.803 回答