在没有 ViewPager 的情况下将点击的片段保存在 TabLayout 中

Question

我有一个 viewpager，里面有 4 个碎片。在其中一个片段中，我还有其他 4 个片段，它们位于 TabLayout 中，没有 ViewPager。如何保留对 TabLayout 中最后显示的片段的引用，并在重新创建整个 TabLayout 时显示该特定片段？我还需要具有以下功能，因为每次单击它们时我都会刷新片段。

    public class HistoryTabFragment extends BaseFragment {

    private static final String ARG_PARAM1 = "param1";
    public static final String GET_MY_HISTORY = HistoryTabFragment.class.getName() + ".my_history";

    FragmentTabHistoryBinding mBinder;
    Shop mShop;
    MyHistoryFragment myHistoryFragment;
    StandardHistoryFragment standardHistoryFragment;
    OpenAccountFragment openAccountFragment;
    BacklogFragment backlogFragment;

    public HistoryTabFragment() {
        // Required empty public constructor
    }

    /**
     * Use this factory method to create a new instance of
     * this fragment using the provided parameters.
     *
     * @return A new instance of fragment HistoryTabFragment.
     */
    public static HistoryTabFragment newInstance(Shop shop) {
        HistoryTabFragment fragment = new HistoryTabFragment();
        Bundle args = new Bundle();
        args.putParcelable(ARG_PARAM1, Parcels.wrap(shop));
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            Parcelable parcelable;
            parcelable = getArguments().getParcelable(ARG_PARAM1);
            mShop = Parcels.unwrap(parcelable);
        }
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        mBinder = DataBindingUtil.inflate(inflater, R.layout.fragment_tab_history, container, false);
        setUpTabLayout();
        bindWidgetWithEvent();
        return mBinder.getRoot();
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        //sendActionToActivity(GET_MY_HISTORY, mShop);
        replaceFragment(myHistoryFragment);
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
    }

    private void setUpTabLayout() {
        myHistoryFragment = MyHistoryFragment.newInstance(mShop);
        standardHistoryFragment = StandardHistoryFragment.newInstance(mShop);
        backlogFragment = BacklogFragment.newInstance(mShop);
        openAccountFragment = OpenAccountFragment.newInstance(mShop);

        mBinder.tabs.addTab(mBinder.tabs.newTab().setText(R.string.my_offers), true);
        mBinder.tabs.addTab(mBinder.tabs.newTab().setText(R.string.standard_offers));
        mBinder.tabs.addTab(mBinder.tabs.newTab().setText(R.string.backlog));
        mBinder.tabs.addTab(mBinder.tabs.newTab().setText(R.string.open_account));
    }

    private void bindWidgetWithEvent() {
        mBinder.tabs.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                setCurrentTabFragment(tab.getPosition());
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {
                setCurrentTabFragment(tab.getPosition());
            }
        });
    }

    private void setCurrentTabFragment(int tabPosition) {
        switch (tabPosition) {
            case 0:
                replaceFragment(myHistoryFragment);
                break;
            case 1:
                replaceFragment(standardHistoryFragment);
                break;
            case 2:
                replaceFragment(backlogFragment);
                break;
            case 3:
                replaceFragment(openAccountFragment);
                break;
        }
    }

    private void replaceFragment(Fragment fragment) {
        FragmentManager fm = getChildFragmentManager();
        FragmentTransaction ft = fm.beginTransaction();
        ft.replace(R.id.frame_container, fragment);
        ft.addToBackStack(null);
        ft.commit();
    }

    @Override
    protected void setTypeface() {

    }

    private void sendActionToActivity(String action, Shop shop) {
        if (mListener == null) {
            return;
        }
        Bundle bundle = new Bundle();
        bundle.putString(Constants.ACTION_KEY, action);
        bundle.putParcelable(Constants.DATA_KEY_1, Parcels.wrap(shop));
        mListener.onFragmentInteraction(bundle);
    }
}

Answer 1

我做到了。我将上次单击的选项卡的位置保存在 SharedPreferences 中，然后在 onViewCreated 中我得到了位置并使用 switch 语句并替换了正确的 fragment.

public class HistoryTabFragment extends BaseFragment {

private static final String ARG_PARAM1 = "param1";
private static final String CURRENT_FRAGMENT = ".current_fragment";
private static final String CURRENT_TAB = ".current_tab";

FragmentTabHistoryBinding mBinder;
Shop mShop;
Fragment mFragment;
PreferenceAdapter mPreferenceAdapter;
int tabPosition;

public HistoryTabFragment() {
    // Required empty public constructor
}

/**
 * Use this factory method to create a new instance of
 * this fragment using the provided parameters.
 *
 * @return A new instance of fragment HistoryTabFragment.
 */
public static HistoryTabFragment newInstance(Shop shop) {
    HistoryTabFragment fragment = new HistoryTabFragment();
    Bundle args = new Bundle();
    args.putParcelable(ARG_PARAM1, Parcels.wrap(shop));
    fragment.setArguments(args);
    return fragment;
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (getArguments() != null) {
        Parcelable parcelable;
        parcelable = getArguments().getParcelable(ARG_PARAM1);
        mShop = Parcels.unwrap(parcelable);
    }
}

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    mBinder = DataBindingUtil.inflate(inflater, R.layout.fragment_tab_history, container, false);
    mPreferenceAdapter = new PreferenceAdapter(getContext());
    setUpTabLayout();
    bindWidgetWithEvent();
    return mBinder.getRoot();
}

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    tabPosition = mPreferenceAdapter.readLastHistoryTabPosition();
    switch (tabPosition) {
        case 0:
            mFragment = MyHistoryFragment.newInstance(mShop);
            mBinder.tabs.getTabAt(tabPosition).select();
            replaceFragment(mFragment);
            break;
        case 1:
            mFragment = StandardHistoryFragment.newInstance(mShop);
            replaceFragment(mFragment);
            mBinder.tabs.getTabAt(tabPosition).select();
            break;
        case 2:
            mFragment = BacklogFragment.newInstance(mShop);
            replaceFragment(mFragment);
            mBinder.tabs.getTabAt(tabPosition).select();
            break;
        case 3:
            mFragment = OpenAccountFragment.newInstance(mShop);
            replaceFragment(mFragment);
            mBinder.tabs.getTabAt(tabPosition).select();
            break;
    }
}

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    getChildFragmentManager().putFragment(outState, CURRENT_FRAGMENT, mFragment);
    outState.putInt(CURRENT_TAB, mBinder.tabs.getSelectedTabPosition());
}

private void setUpTabLayout() {
    mBinder.tabs.addTab(mBinder.tabs.newTab().setText(R.string.my_offers));
    mBinder.tabs.addTab(mBinder.tabs.newTab().setText(R.string.standard_offers));
    mBinder.tabs.addTab(mBinder.tabs.newTab().setText(R.string.backlog));
    mBinder.tabs.addTab(mBinder.tabs.newTab().setText(R.string.open_account));
}

private void bindWidgetWithEvent() {
    mBinder.tabs.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {
            setCurrentTabFragment(tab.getPosition());
        }

        @Override
        public void onTabUnselected(TabLayout.Tab tab) {

        }

        @Override
        public void onTabReselected(TabLayout.Tab tab) {
            setCurrentTabFragment(tab.getPosition());
        }
    });
}

private void setCurrentTabFragment(int tabPosition) {
    switch (tabPosition) {
        case 0:
            mFragment = MyHistoryFragment.newInstance(mShop);
            replaceFragment(mFragment);
            break;
        case 1:
            mFragment = StandardHistoryFragment.newInstance(mShop);
            replaceFragment(mFragment);
            break;
        case 2:
            mFragment = BacklogFragment.newInstance(mShop);
            replaceFragment(mFragment);
            break;
        case 3:
            mFragment = OpenAccountFragment.newInstance(mShop);
            replaceFragment(mFragment);
            break;
    }
    mPreferenceAdapter.writeLastHistoryTabPosition(mBinder.tabs.getSelectedTabPosition());
    mPreferenceAdapter.apply();
}

private void replaceFragment(Fragment fragment) {
    FragmentManager fm = getChildFragmentManager();
    FragmentTransaction ft = fm.beginTransaction();
    ft.replace(R.id.frame_container, fragment);
    ft.addToBackStack(null);
    ft.commit();
}
}

在没有 ViewPager 的情况下将点击的片段保存在 TabLayout 中

Saving the clicked fragment in TabLayout without ViewPager

android

android-fragments

android-viewpager

android-tablayout