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
最佳答案
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。
关于Android 标签 fragment ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12738447/