Android 标签 fragment

Question

我的标签 fragment 似乎没有显示任何内容。我知道我的代码中一定缺少某些东西。有人可以帮我吗？以下是我的尝试。

根据UgglyNoodle的建议修改

问题:我的 fragment 选项卡没有显示任何内容。

主 Activity .java

  public class MainActivity extends SherlockFragmentActivity implements TabListener {
    private Fragment mFragment;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        ActionBar actionBar = getSupportActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        actionBar.setDisplayShowTitleEnabled(true);

        //mFragment = new AppleFragment();

        Tab tab = actionBar.newTab()
                .setText("Apple")
                .setTabListener(this)
                .setIcon(R.drawable.apple);

        actionBar.addTab(tab);


    }

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
         if (mFragment == null) {
                mFragment = new AppleFragment();
                ft.add(android.R.id.content, mFragment);
            } else {
                ft.attach(mFragment);
            }
    }

    @Override
    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
        ft.detach(mFragment);
    }

    @Override
    public void onTabReselected(Tab tab, FragmentTransaction ft) {
    }
}

苹果 fragment .java

    public class AppleFragment extends SherlockListFragment{


        static final String URL = "http://api.androidhive.info/pizza/?format=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_COST = "cost";
        static final String KEY_DESC = "description";



        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){

        return super.onCreateView(inflater, container, savedInstanceState);

        }


        public void onActivityCreated(Bundle savedInstanceState) {

            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_COST, "Rs." + parser.getValue(e, KEY_COST));
                map.put(KEY_DESC, parser.getValue(e, KEY_DESC));

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

            ListAdapter adapter = new SimpleAdapter(getActivity(), menuItems,
                    R.layout.list_item,
                    new String[] { KEY_NAME, KEY_DESC, KEY_COST }, new int[] {
                            R.id.name, R.id.desciption, R.id.cost });


            setListAdapter(adapter);    


        }
}

XML解析器.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;
    }

    /** Getting node value
      * @param elem element
      */
     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 "";
     }

     /**
      * Getting node value
      * @param Element node
      * @param key string
      * */
     public String getValue(Element item, String str) {     
            NodeList n = item.getElementsByTagName(str);        
            return this.getElementValue(n.item(0));
        }
}

日志:

10-05 16:24:30.031: E/AndroidRuntime(19244): FATAL EXCEPTION: main
10-05 16:24:30.031: E/AndroidRuntime(19244): java.lang.RuntimeException: Unable to start activity ComponentInfo{in.wptrafficanalyzer.actionbarsherlocknavtab/in.wptrafficanalyzer.actionbarsherlocknavtab.MainActivity}: android.os.NetworkOnMainThreadException
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1970)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1995)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.app.ActivityThread.access$600(ActivityThread.java:127)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1161)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.os.Handler.dispatchMessage(Handler.java:99)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.os.Looper.loop(Looper.java:137)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.app.ActivityThread.main(ActivityThread.java:4512)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at java.lang.reflect.Method.invokeNative(Native Method)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at java.lang.reflect.Method.invoke(Method.java:511)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:982)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:749)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at dalvik.system.NativeStart.main(Native Method)
10-05 16:24:30.031: E/AndroidRuntime(19244): Caused by: android.os.NetworkOnMainThreadException
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1099)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at java.net.InetAddress.lookupHostByName(InetAddress.java:391)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at java.net.InetAddress.getAllByName(InetAddress.java:220)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at in.wptrafficanalyzer.actionbarsherlocknavtab.XMLParser.getXmlFromUrl(XMLParser.java:45)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at in.wptrafficanalyzer.actionbarsherlocknavtab.AppleFragment.onCreate(AppleFragment.java:50)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:834)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1080)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:622)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1416)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:505)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1136)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.app.Activity.performStart(Activity.java:4475)
10-05 16:24:30.031: E/AndroidRuntime(19244):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1943)
10-05 16:24:30.031: E/AndroidRuntime(19244):    ... 11 more

Answer 1

您不需要 AppleFragment 类。相反，您可以让 MainActivity 实现 TabListener。这里有一些快速代码，可以为您提供基本概念，但我尚未对其进行测试，需要进行一些修复。

public class MainActivity extends SherlockFragmentActivity implements TabListener {
    private Fragment mFragment;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        ActionBar actionBar = getSupportActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        actionBar.setDisplayShowTitleEnabled(true);

        Tab tab = actionBar.newTab()
                .setText("Apple")
                .setTabListener(this)
                .setIcon(R.drawable.apple);

        actionBar.addTab(tab);
    }

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
    if (mFragment == null) {
        mFragment = new ArrayListFragment();
        ft.add(R.id.content, mFragment, "some_tag");
    } else {
        ft.attach(mFragment);
    }

    @Override
    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
        ft.detach(mFragment);
    }

    @Override
    public void onTabReselected(Tab tab, FragmentTransaction ft) {
    }
}

当您有多个选项卡时，您将需要跟踪多个 fragment ，并根据所选选项卡附加和分离正确的 fragment 。

最后，您的 ArrayListFragment 应该扩展 ListFragment，您仍然可以使用 setListAdapter() 等等。

This page有一个很好的例子，尽管它比我建议的要复杂一些。