每次我在android中单击选项卡时，都会以片段形式重新加载数据

我已经创建了一个应用程序的布局有三个标签在安卓2.3。每个选项卡都有一个片段，每个片段中都有一个列表视图。列表视图中显示的所有数据都来自互联网，数据总是会发生变化，所以每次我看到那个片段时，我都想重新加载数据。例如，我现在正在观看“tab1”，当我单击“tab2”时，“tab2”中的数据将重新加载，“tab1”中的数据也将重新加载。我试过了

ft.detach（frg）；
固定支架（frg）；
ft.commit（）

但总有错误

这是我的密码

main活动

public class MainActivity extends ActionBarActivity {

    private ViewPager pager;
    private TabsAdapter mTabsAdapter;

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

        pager = new ViewPager(this);
        pager.setId(R.id.pager);
        setContentView(pager);

        final ActionBar bar = getSupportActionBar();  
        bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        mTabsAdapter = new TabsAdapter(this, getSupportActionBar(), pager);
        mTabsAdapter.addTab(bar.newTab().setText("tab1"), Tab1.class, null);
        mTabsAdapter.addTab(bar.newTab().setText("tab2"), Tab2.class, null);
        mTabsAdapter.addTab(bar.newTab().setText("tab3"), Tab3.class, null);
    }
}

public class Tab1 extends ListFragment{
    private String result;
    protected ArrayAdapter listAdapter;
    private ArrayList<String> items = new ArrayList<String>();
    final String uri = "http://localhost/sample.php";

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
        View rootView = inflater.inflate(R.layout.list, container, false);
        items.clear();
        Thread t = new Thread(new sendPostRunnable());
        t.start();
        listAdapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, items);
        setListAdapter(listAdapter);
        return rootView;
    }

    class sendPostRunnable implements Runnable{
        @Override
        public void run(){
            result = sendPostDataToInternet();
            String temp = "Not result.";
            try {
                JSONTokener jsonTokener = new JSONTokener(result); 
                JSONObject jsonObject = (JSONObject) jsonTokener.nextValue(); 
                JSONArray jarray = jsonObject.getJSONArray("response");
                for (int i = 0; i < jarray.length(); i++) { 
                    temp = "";
                    JSONObject jobject = jarray.getJSONObject(i); 
                    temp += "Name: "+jobject.getString("name")+"\n"; 
                    temp += "Email: "+jobject.getString("email"); 
                    items.add(temp);
                    temp = "";
                } 
                if(jarray.length() < 1){
                    items.add(temp);
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            getActivity().runOnUiThread(new Runnable() {
                public void run() {
                    listAdapter.notifyDataSetChanged();
                }
            });

        }
    }

    private String sendPostDataToInternet(){
        HttpPost httpRequest = new HttpPost(uri);
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        try{
            httpRequest.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
            HttpResponse httpResponse = new DefaultHttpClient().execute(httpRequest);
            if (httpResponse.getStatusLine().getStatusCode() == 200){
                String strResult = EntityUtils.toString(httpResponse.getEntity());
                return strResult;
            }
        } catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }
}

public class TabsAdapter extends FragmentPagerAdapter implements TabListener, OnPageChangeListener{
    private final Context mContext;
    private final ActionBar mActionBar;
    private final ViewPager mViewPager;
    private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
    private final String TAG = "";

    static final class TabInfo{
        private final Class<?> clss;
        private final Bundle args;

        TabInfo(Class<?> _class, Bundle _args){
            clss = _class;
            args = _args;
        }
    }

    public TabsAdapter(FragmentActivity activity, ActionBar bar, ViewPager pager) {
        super(activity.getSupportFragmentManager());
        mContext = activity;
        mActionBar = bar;
        mViewPager = pager;
        mViewPager.setAdapter(this);
        mViewPager.setOnPageChangeListener(this);

    }

    public void addTab(Tab tab, Class<?> clss, Bundle args){
        TabInfo info = new TabInfo(clss, args);
        tab.setTag(info);
        tab.setTabListener(this);
        mTabs.add(info);
        mActionBar.addTab(tab);
        notifyDataSetChanged();
    }

    @Override
    public void onPageSelected(int position) {
        mActionBar.setSelectedNavigationItem(position); 
    }

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        mViewPager.setCurrentItem(tab.getPosition());
        Log.v(TAG, "clicked");
        Object tag = tab.getTag();
        for (int i = 0; i<mTabs.size(); i++){
            if (mTabs.get(i) == tag){
                mViewPager.setCurrentItem(i);
            }
        }
    }

    @Override
    public Fragment getItem(int position) {
        TabInfo info = mTabs.get(position);
        return Fragment.instantiate(mContext, info.clss.getName(), info.args);
    }

    @Override
    public int getCount() {
        return mTabs.size();
    }
}

Tab1

public class MainActivity extends ActionBarActivity {

    private ViewPager pager;
    private TabsAdapter mTabsAdapter;

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

        pager = new ViewPager(this);
        pager.setId(R.id.pager);
        setContentView(pager);

        final ActionBar bar = getSupportActionBar();  
        bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        mTabsAdapter = new TabsAdapter(this, getSupportActionBar(), pager);
        mTabsAdapter.addTab(bar.newTab().setText("tab1"), Tab1.class, null);
        mTabsAdapter.addTab(bar.newTab().setText("tab2"), Tab2.class, null);
        mTabsAdapter.addTab(bar.newTab().setText("tab3"), Tab3.class, null);
    }
}

public class Tab1 extends ListFragment{
    private String result;
    protected ArrayAdapter listAdapter;
    private ArrayList<String> items = new ArrayList<String>();
    final String uri = "http://localhost/sample.php";

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
        View rootView = inflater.inflate(R.layout.list, container, false);
        items.clear();
        Thread t = new Thread(new sendPostRunnable());
        t.start();
        listAdapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, items);
        setListAdapter(listAdapter);
        return rootView;
    }

    class sendPostRunnable implements Runnable{
        @Override
        public void run(){
            result = sendPostDataToInternet();
            String temp = "Not result.";
            try {
                JSONTokener jsonTokener = new JSONTokener(result); 
                JSONObject jsonObject = (JSONObject) jsonTokener.nextValue(); 
                JSONArray jarray = jsonObject.getJSONArray("response");
                for (int i = 0; i < jarray.length(); i++) { 
                    temp = "";
                    JSONObject jobject = jarray.getJSONObject(i); 
                    temp += "Name: "+jobject.getString("name")+"\n"; 
                    temp += "Email: "+jobject.getString("email"); 
                    items.add(temp);
                    temp = "";
                } 
                if(jarray.length() < 1){
                    items.add(temp);
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            getActivity().runOnUiThread(new Runnable() {
                public void run() {
                    listAdapter.notifyDataSetChanged();
                }
            });

        }
    }

    private String sendPostDataToInternet(){
        HttpPost httpRequest = new HttpPost(uri);
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        try{
            httpRequest.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
            HttpResponse httpResponse = new DefaultHttpClient().execute(httpRequest);
            if (httpResponse.getStatusLine().getStatusCode() == 200){
                String strResult = EntityUtils.toString(httpResponse.getEntity());
                return strResult;
            }
        } catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }
}

public class TabsAdapter extends FragmentPagerAdapter implements TabListener, OnPageChangeListener{
    private final Context mContext;
    private final ActionBar mActionBar;
    private final ViewPager mViewPager;
    private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
    private final String TAG = "";

    static final class TabInfo{
        private final Class<?> clss;
        private final Bundle args;

        TabInfo(Class<?> _class, Bundle _args){
            clss = _class;
            args = _args;
        }
    }

    public TabsAdapter(FragmentActivity activity, ActionBar bar, ViewPager pager) {
        super(activity.getSupportFragmentManager());
        mContext = activity;
        mActionBar = bar;
        mViewPager = pager;
        mViewPager.setAdapter(this);
        mViewPager.setOnPageChangeListener(this);

    }

    public void addTab(Tab tab, Class<?> clss, Bundle args){
        TabInfo info = new TabInfo(clss, args);
        tab.setTag(info);
        tab.setTabListener(this);
        mTabs.add(info);
        mActionBar.addTab(tab);
        notifyDataSetChanged();
    }

    @Override
    public void onPageSelected(int position) {
        mActionBar.setSelectedNavigationItem(position); 
    }

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        mViewPager.setCurrentItem(tab.getPosition());
        Log.v(TAG, "clicked");
        Object tag = tab.getTag();
        for (int i = 0; i<mTabs.size(); i++){
            if (mTabs.get(i) == tag){
                mViewPager.setCurrentItem(i);
            }
        }
    }

    @Override
    public Fragment getItem(int position) {
        TabInfo info = mTabs.get(position);
        return Fragment.instantiate(mContext, info.clss.getName(), info.args);
    }

    @Override
    public int getCount() {
        return mTabs.size();
    }
}

public类Tab1扩展了ListFragment{
私有字符串结果；
受保护的阵列适配器列表适配器；
private ArrayList items=new ArrayList（）；
最终字符串uri=”http://localhost/sample.php";
CreateView上的公共视图（布局、充气机、视图组容器、捆绑包保存状态）{
视图根视图=充气机。充气（R.layout.list，容器，false）；
items.clear（）；
线程t=新线程（new sendPostRunnable（））；
t、 start（）；
listAdapter=new ArrayAdapter（getActivity（），android.R.layout.simple\u list\u item\u 1，items）；
setListAdapter（listAdapter）；
返回rootView；
}
类sendPostRunnable实现Runnable{
@凌驾
公开募捐{
结果=sendPostDataToInternet（）；
字符串temp=“非结果。”；
试一试{
JSONTokener JSONTokener=新的JSONTokener（结果）；
JSONObject JSONObject=（JSONObject）jsonTokener.nextValue（）；
JSONArray jarray=jsonObject.getJSONArray（“响应”）；
对于（inti=0；i

TabsAdapter

public class MainActivity extends ActionBarActivity {

    private ViewPager pager;
    private TabsAdapter mTabsAdapter;

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

        pager = new ViewPager(this);
        pager.setId(R.id.pager);
        setContentView(pager);

        final ActionBar bar = getSupportActionBar();  
        bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        mTabsAdapter = new TabsAdapter(this, getSupportActionBar(), pager);
        mTabsAdapter.addTab(bar.newTab().setText("tab1"), Tab1.class, null);
        mTabsAdapter.addTab(bar.newTab().setText("tab2"), Tab2.class, null);
        mTabsAdapter.addTab(bar.newTab().setText("tab3"), Tab3.class, null);
    }
}

public class Tab1 extends ListFragment{
    private String result;
    protected ArrayAdapter listAdapter;
    private ArrayList<String> items = new ArrayList<String>();
    final String uri = "http://localhost/sample.php";

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
        View rootView = inflater.inflate(R.layout.list, container, false);
        items.clear();
        Thread t = new Thread(new sendPostRunnable());
        t.start();
        listAdapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, items);
        setListAdapter(listAdapter);
        return rootView;
    }

    class sendPostRunnable implements Runnable{
        @Override
        public void run(){
            result = sendPostDataToInternet();
            String temp = "Not result.";
            try {
                JSONTokener jsonTokener = new JSONTokener(result); 
                JSONObject jsonObject = (JSONObject) jsonTokener.nextValue(); 
                JSONArray jarray = jsonObject.getJSONArray("response");
                for (int i = 0; i < jarray.length(); i++) { 
                    temp = "";
                    JSONObject jobject = jarray.getJSONObject(i); 
                    temp += "Name: "+jobject.getString("name")+"\n"; 
                    temp += "Email: "+jobject.getString("email"); 
                    items.add(temp);
                    temp = "";
                } 
                if(jarray.length() < 1){
                    items.add(temp);
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            getActivity().runOnUiThread(new Runnable() {
                public void run() {
                    listAdapter.notifyDataSetChanged();
                }
            });

        }
    }

    private String sendPostDataToInternet(){
        HttpPost httpRequest = new HttpPost(uri);
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        try{
            httpRequest.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
            HttpResponse httpResponse = new DefaultHttpClient().execute(httpRequest);
            if (httpResponse.getStatusLine().getStatusCode() == 200){
                String strResult = EntityUtils.toString(httpResponse.getEntity());
                return strResult;
            }
        } catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }
}

public class TabsAdapter extends FragmentPagerAdapter implements TabListener, OnPageChangeListener{
    private final Context mContext;
    private final ActionBar mActionBar;
    private final ViewPager mViewPager;
    private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
    private final String TAG = "";

    static final class TabInfo{
        private final Class<?> clss;
        private final Bundle args;

        TabInfo(Class<?> _class, Bundle _args){
            clss = _class;
            args = _args;
        }
    }

    public TabsAdapter(FragmentActivity activity, ActionBar bar, ViewPager pager) {
        super(activity.getSupportFragmentManager());
        mContext = activity;
        mActionBar = bar;
        mViewPager = pager;
        mViewPager.setAdapter(this);
        mViewPager.setOnPageChangeListener(this);

    }

    public void addTab(Tab tab, Class<?> clss, Bundle args){
        TabInfo info = new TabInfo(clss, args);
        tab.setTag(info);
        tab.setTabListener(this);
        mTabs.add(info);
        mActionBar.addTab(tab);
        notifyDataSetChanged();
    }

    @Override
    public void onPageSelected(int position) {
        mActionBar.setSelectedNavigationItem(position); 
    }

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        mViewPager.setCurrentItem(tab.getPosition());
        Log.v(TAG, "clicked");
        Object tag = tab.getTag();
        for (int i = 0; i<mTabs.size(); i++){
            if (mTabs.get(i) == tag){
                mViewPager.setCurrentItem(i);
            }
        }
    }

    @Override
    public Fragment getItem(int position) {
        TabInfo info = mTabs.get(position);
        return Fragment.instantiate(mContext, info.clss.getName(), info.args);
    }

    @Override
    public int getCount() {
        return mTabs.size();
    }
}

公共类TabsAdapter扩展了FragmentPagerAdapter，实现了TabListener、OnPageChangeListener{
私有最终上下文mContext；
私人终审法院；
专用最终查看页面mViewPager；
private final ArrayList mtab=new ArrayList（）；
私有最终字符串标记=”；
静态最终类TabInfo{
私人期末班；
私有最终包args；
TabInfo（类_类，捆绑参数）{
clss=_类；
args=_args；
}
}
公共选项卡dapter（片段活动、操作栏、ViewPager寻呼机）{
super（activity.getSupportFragmentManager（））；
mContext=活动；
mActionBar=bar；
mViewPager=寻呼机；
mViewPager.setAdapter（此）；
mViewPager.setOnPageChangeListener（此）；
}
public void addTab（选项卡、类cls、Bundle args）{
TabInfo=新的TabInfo（clss，args）；
tab.setTag（信息）；
tab.setTableListener（此）；
添加（信息）；
mActionBar.addTab（tab）；
notifyDataSetChanged（）；
}
@凌驾
已选择页面上的公共无效（内部位置）{
mActionBar.setSelectedNavigationItem（位置）；
}
@凌驾
已选择的公共事务（选项卡，碎片事务ft）{
setCurrentItem（tab.getPosition（））；
Log.v（标记“点击”）；
Object tag=tab.getTag（）；
对于（int i=0；i在片段中推进一些接口，如
onmyrefreshlister
，然后：

public void onPageSelected(int position) { 
    ((OnMyRefreshListener)pagerViewAdapter.getItem()).onMyRefresh();
}

我在以前的应用程序中遇到了同样的问题

无需更多更改，只需在MainActivity.java中添加一行即可

public class MainActivity extends ActionBarActivity {

    private ViewPager pager;
    private TabsAdapter mTabsAdapter;

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

        pager = new ViewPager(this);
        pager.setId(R.id.pager);
        setContentView(pager);

        final ActionBar bar = getSupportActionBar();  
        bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        mTabsAdapter = new TabsAdapter(this, getSupportActionBar(), pager);
        mTabsAdapter.addTab(bar.newTab().setText("tab1"), Tab1.class, null);
        mTabsAdapter.addTab(bar.newTab().setText("tab2"), Tab2.class, null);
        mTabsAdapter.addTab(bar.newTab().setText("tab3"), Tab3.class, null);
    }
}

public class Tab1 extends ListFragment{
    private String result;
    protected ArrayAdapter listAdapter;
    private ArrayList<String> items = new ArrayList<String>();
    final String uri = "http://localhost/sample.php";

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
        View rootView = inflater.inflate(R.layout.list, container, false);
        items.clear();
        Thread t = new Thread(new sendPostRunnable());
        t.start();
        listAdapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, items);
        setListAdapter(listAdapter);
        return rootView;
    }

    class sendPostRunnable implements Runnable{
        @Override
        public void run(){
            result = sendPostDataToInternet();
            String temp = "Not result.";
            try {
                JSONTokener jsonTokener = new JSONTokener(result); 
                JSONObject jsonObject = (JSONObject) jsonTokener.nextValue(); 
                JSONArray jarray = jsonObject.getJSONArray("response");
                for (int i = 0; i < jarray.length(); i++) { 
                    temp = "";
                    JSONObject jobject = jarray.getJSONObject(i); 
                    temp += "Name: "+jobject.getString("name")+"\n"; 
                    temp += "Email: "+jobject.getString("email"); 
                    items.add(temp);
                    temp = "";
                } 
                if(jarray.length() < 1){
                    items.add(temp);
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            getActivity().runOnUiThread(new Runnable() {
                public void run() {
                    listAdapter.notifyDataSetChanged();
                }
            });

        }
    }

    private String sendPostDataToInternet(){
        HttpPost httpRequest = new HttpPost(uri);
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        try{
            httpRequest.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
            HttpResponse httpResponse = new DefaultHttpClient().execute(httpRequest);
            if (httpResponse.getStatusLine().getStatusCode() == 200){
                String strResult = EntityUtils.toString(httpResponse.getEntity());
                return strResult;
            }
        } catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }
}

public class TabsAdapter extends FragmentPagerAdapter implements TabListener, OnPageChangeListener{
    private final Context mContext;
    private final ActionBar mActionBar;
    private final ViewPager mViewPager;
    private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
    private final String TAG = "";

    static final class TabInfo{
        private final Class<?> clss;
        private final Bundle args;

        TabInfo(Class<?> _class, Bundle _args){
            clss = _class;
            args = _args;
        }
    }

    public TabsAdapter(FragmentActivity activity, ActionBar bar, ViewPager pager) {
        super(activity.getSupportFragmentManager());
        mContext = activity;
        mActionBar = bar;
        mViewPager = pager;
        mViewPager.setAdapter(this);
        mViewPager.setOnPageChangeListener(this);

    }

    public void addTab(Tab tab, Class<?> clss, Bundle args){
        TabInfo info = new TabInfo(clss, args);
        tab.setTag(info);
        tab.setTabListener(this);
        mTabs.add(info);
        mActionBar.addTab(tab);
        notifyDataSetChanged();
    }

    @Override
    public void onPageSelected(int position) {
        mActionBar.setSelectedNavigationItem(position); 
    }

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        mViewPager.setCurrentItem(tab.getPosition());
        Log.v(TAG, "clicked");
        Object tag = tab.getTag();
        for (int i = 0; i<mTabs.size(); i++){
            if (mTabs.get(i) == tag){
                mViewPager.setCurrentItem(i);
            }
        }
    }

    @Override
    public Fragment getItem(int position) {
        TabInfo info = mTabs.get(position);
        return Fragment.instantiate(mContext, info.clss.getName(), info.args);
    }

    @Override
    public int getCount() {
        return mTabs.size();
    }
}

viewPager.setOffscreenPageLimit（）；

如果有三个选项卡，则将viewPager.setOffscreenPageLimit（3）