Question

screen shot

喜这是我在照片中的项目。我的项目在每个页面都有自定义listView，listViews用json数据填充。

我写了每个标签的onCreateView事件Toast消息，以澄清问题，看看发生了什么。

例如，当我点击第2个标签时，我得到“2个工作”，然后“3个工作”作为吐司消息。也一遍又一遍地向listview添加相同的数据btw。

抱歉，如果我无法解释我的问题。

这是我的代码。

public class TabsPagerAdapter extends FragmentPagerAdapter {

public TabsPagerAdapter(FragmentManager fm) {
    super(fm);
}

@Override
public Fragment getItem(int index) {

    switch (index) {
    case 0:
        return new VasitaTurFragment();
         .
         .
         .
    return null;
}
@Override
public int getCount() {
    // get item count - equal to number of tabs
    return 6;
}

MainActivity：

public class MainActivity extends FragmentActivity implements
    ActionBar.TabListener {
private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
private String[] tabs = { "1", "2", "3","4","5","6" };
ModelFragment mF= new ModelFragment();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    viewPager = (ViewPager) findViewById(R.id.pager);
    actionBar = getActionBar();
    mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
    viewPager.setAdapter(mAdapter);
    actionBar.setHomeButtonEnabled(false);

    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

    for (String tab_name : tabs) {
        actionBar.addTab(actionBar.newTab().setText(tab_name)
                .setTabListener(this));
    }
    viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {

            actionBar.setSelectedNavigationItem(position);
        }
        @Override
        public void onPageScrolled(int arg0, float arg1, int arg2) {
        }
        @Override
        public void onPageScrollStateChanged(int arg0) {
        }
    });
}
@Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
}
@Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
    viewPager.setCurrentItem(tab.getPosition());
}
@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
}
}

片段：

public class MenseiFragment extends Fragment {
private static final String TAG = MainActivity.class.getSimpleName();    
private ProgressDialog pDialog;
private List<Mensei> menseiList = new ArrayList<Mensei>();
private ListView listView;
private menseiCLA adapter;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    final View rootView = inflater.inflate(R.layout.mensei, container, false);
    listView = (ListView) rootView.findViewById(R.id.listView1);
    adapter = new menseiCLA(getActivity(), menseiList);
    listView.setAdapter(adapter);
    Toast.makeText(getActivity(),"2 worked",
            Toast.LENGTH_LONG).show();

    JsonArrayRequest commonReq = new JsonArrayRequest(url,
            new Response.Listener<JSONArray>() {
                @Override
                public void onResponse(JSONArray response) {
                    Log.d(TAG, response.toString());

                    for (int i = 0; i < response.length(); i++) {
                        try {

                            JSONObject objAna = response.getJSONObject(i);
                            Mensei mensei = new Mensei();
                            .
                            .

                            menseiList.add(mensei);

                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                    adapter.notifyDataSetChanged();
                }
            }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            VolleyLog.d(TAG, "Error: " + error.getMessage());
        }
    });
    AppController.getInstance().addToRequestQueue(commonReq);
    return rootView;
}

@Override
public void onDestroy() {
    super.onDestroy();
    hidePDialog();
}}

Answer 1

这是viewpager的默认行为，因此如果您单击每个选项卡，则会自动创建它的两个邻居，并且都在onResume中运行。如果你真的希望他们只在可见时才做某事，请在每个标签片段的函数下面使用：

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    if(isVisible()){
        if(isVisibleToUser){
            Log.d("MyTag","My Fragment is visible");
        }else{
            Log.d("MyTag","My Fragment is not visible");
        }
    }
}

ViewPager选项卡在选定之前运行并连续重新加载选项卡

1 个答案: