viewpager中有多个片段。片段A，片段B，片段C和片段D。片段C用另一个扩展列表片段的片段替换自己。我只想看到片段C时要替换片段。因为有一些后台AsyncTask正在执行，当选择片段C时应该执行该任务。我已经替换了工作正常的片段。但是问题在于它的状态正在保存。因为每当调用Fragment C的邻居时，也会自动调用Fragment C内部替换的片段
我已经实现了所有代码。当片段C的邻居片段被调用时，我只是不想调用替换片段
public class VendorsListFragment extends Fragment {
private static final String TAG = VendorsActivity.class.getSimpleName();
@BindView(R.id.layoutAdViewBottomVendorActivity)
AdView mAdView;
View view;
boolean isLaunched= false;
boolean isRejected= false;
public VendorsListFragment() {
}
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
view = inflater.inflate(R.layout.activity_vendors, container, false);
ButterKnife.bind(this, view);
return view;
}
public void callNewFragment() {
FragmentManager manager = getChildFragmentManager();
FragmentTransaction ft = manager.beginTransaction();
VendorFragment vendorFragment = new VendorFragment();
ft.remove(vendorFragment);
ft.replace(R.id.vendorFragmentContainer, new VendorFragment());
//container is the ViewGroup of current fragment
ft.addToBackStack(null);
ft.commit();
ft.commitAllowingStateLoss();
}
}
具有ViewPager的活动具有以下代码
public class NetworkToolsActivity extends AppCompatActivity {
TabLayout tabHost;
public ViewPager pager;
ViewPagerAdapter adapter;
private Resources res;
int tabPosition;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
initializeMainContext(this);
setContentView(R.layout.activity_network_tools);
res = this.getResources();
Intent mIntent = getIntent();
int selectedTab = mIntent.getIntExtra("tabPosition", 0);
Toolbar toolbar = (Toolbar) this.findViewById(R.id.toolbar);
toolbar.setTitleTextColor(Color.WHITE);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowHomeEnabled(true);
this.setSupportActionBar(toolbar);
tabHost = findViewById(R.id.tabHost);
pager = (ViewPager) this.findViewById(R.id.pager );
adapter = new ViewPagerAdapter(getSupportFragmentManager());
pager.setAdapter(adapter);
final int pageMargin = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 4, getResources()
.getDisplayMetrics());
pager.setPageMargin(pageMargin);
tabHost.setupWithViewPager(pager);
pager.setCurrentItem(selectedTab);
pager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
if (position==6){
VendorsListFragment frag = (VendorsListFragment)adapter.getItem(position);
frag.callNewFragment();
}
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
}
}
ViewPager适配器类
public class ViewPagerAdapter extends FragmentStatePagerAdapter {
public ViewPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
Fragment frag = null;
switch (position) {
case 0:
frag = new SpeedTestFragment();
break;
case 1:
frag = new LanScanFragment();
break;
case 2:
frag = new IpToolFragment();
break;
case 3:
frag = new RouterFinderFragment();
break;
case 4:
frag = new NetworkInformationFragment();
break;
case 5:
frag = new ChannelRatingFragment();
break;
case 6:
frag = new VendorsListFragment();
break;
case 7:
frag = new AccessPointsFragment();
break;
case 8:
frag = new ChannelRatingFragment();
break;
case 9:
frag = new ChannelGraphFragment();
break;
case 10:
frag = new TimeGraphFragment();
break;
}
return frag;
}
@Override
public int getCount() {
return 11;
}
@Nullable
@Override
public CharSequence getPageTitle(int position) {
CharSequence sequence = null;
switch (position) {
case 0:
sequence = "Speed Test";
break;
case 1:
sequence = "Lan Scan";
break;
case 2:
sequence = "Ip Tools";
break;
case 3:
sequence = "Router Finder";
break;
case 4:
sequence = "Network Information";
break;
case 5:
sequence = "Available Channels";
break;
case 6:
sequence = "Vendors";
break;
case 7:
sequence = "Access Point";
break;
case 8:
sequence = "Channel Rating";
break;
case 9:
sequence = "Channel Graph";
break;
case 10:
sequence = "Time Graph";
break;
}
return sequence;
}
}
答案 0 :(得分：0)
您需要获取 ViewPager 的CurrentItem，以查看它是否位于第三位置。
if (getActivity() != null && ((YourActivity)getActivity()).viewPager.getCurrentItem() == 2){
// Call ReplaceFragment here
}
内部活动，您需要实施ViewPager OnPageChangeListener。它具有 onPageSelected 方法，可为您提供页面的位置。每当您更改片段时，它将始终被调用。
编辑
在onPageSelected内部
if (position == 2){
YourFragment frag = (YourFragment)adapter.getItem(position)
frag.callNewFragment()
}
编辑2
import android.os.Parcelable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import java.util.ArrayList;
import java.util.List;
public class ViewPagerAdapter extends FragmentStatePagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public ViewPagerAdapter(FragmentManager fm) {
super(fm);
mFragmentList.clear();
mFragmentTitleList.clear();
}
@Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
@Override
public int getCount() {
return mFragmentList.size();
}
public void addFragment(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
@Override
public Parcelable saveState() {
return null;
}
@Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
，然后添加如下片段：
adapter.addFragment(new SpeedTestFragment(), "Speed Test");
// add all 11 like above
adapter.notifyDataSetChanged();