【发布时间】：2018-06-14 23:09:23
【问题描述】：
我有一个使用 viewpager 和片段托管 tablayout 的活动。我已经成功地使用来自本地数据库的用户填充值设置了 tablayout 和 viewpager，如下面的代码（尽量简短，这里只显示一个选项卡）-
public void setUpTabs() {
setUpViewPager(viewPager);
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
tabLayout.setTabMode(TabLayout.MODE_SCROLLABLE);
tabLayout.setupWithViewPager(viewPager);
}
private void setUpViewPager(ViewPager viewPager) {
Customize customize = new Select()
.from(Customize.class)
.where("tabName = ? ", Constants.NATURE)
.executeSingle();
if (customize != null) {
String nature = customize.tabName;
Log.d(TAG, "Nature Tab Name:\t" + nature);
}
pagerAdapter = new TabsPagerAdapter(getSupportFragmentManager());
pagerAdapter.addTab(new Top30Fragment(), Constants.Top30); // default tab
if (nature != null) {
pagerAdapter.addTab(new NatureFragment(), Constants.NATURE); // dynamic tab from db
}
pagerAdapter.addTabAtLastPosition(new PrefsFragment(), Constants.PREFS);
viewPager.setAdapter(pagerAdapter);
}
Customize 是模型类，我使用 ActiveAndroid 库进行持久化。这是我的 tabsadapter 类代码：
public class TabsPagerAdapter extends FragmentPagerAdapter {
private static final String TAG = TabsPagerAdapter.class.getSimpleName();
private List<Fragment> fragmentList = new ArrayList<>();
private List<String> titlesList = new ArrayList<>();
private ViewPager viewPager;
private TabLayout tabLayout;
public TabsPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
return fragmentList.get(position);
}
@Override
public int getCount() {
return fragmentList.size();
}
public void addTab(Fragment fragment, String name){
fragmentList.add(fragment);
titlesList.add(name);
}
public void addTabAtLastPosition(Fragment fragment, String name){
fragmentList.add(fragmentList.size(), fragment);
titlesList.add(name);
}
public void removeTab(Fragment fragment, String name){ //Not working
for (int i = 0; i < fragmentList.size(); i++){
if (fragmentList.get(i).equals(fragment)){ // never enters/returns from this loop
Log.d(TAG, "Fragment at position:\t" + i);
fragmentList.remove(fragment);
titlesList.remove(name);
}
}
}
@Nullable
@Override
public CharSequence getPageTitle(int position) {
return titlesList.get(position);
}
}
在我的首选项片段（也是 tablayout 的一部分）中，我有一个带有复选框的 recyclerview，case1：如果选中，则在 db 中选中该选项卡，如果还没有，则仅添加到 tablayout。 case2：否则如果不勾选，则表示tab在layout和db中，必须从两者中移除。
我已经开始处理案例 2，但我只能从 db 中删除值，要删除的选项卡仍然存在于 tablayout 中。这是我删除标签的recyclerview适配器代码：
public class PrefsAdapter extends RecyclerView.Adapter<PrefsCustomizeViewHolder> {
private static final String TAG = PrefsAdapter.class.getSimpleName();
private final Context context;
private List<Customize> itemsList;
private long id_nature, id_space, id_seasons, id_art, id_scifi, id_misc;
private Customize cust; // Model class for saving and retrieving tabs
private TabsPagerAdapter pagerAdapter;
private String nature, space, seasons, art, scifi, misc;
private String tabNature, tabSpace, tabSeasons, tabArt, tabScifi, tabMisc;
public PrefsAdapter(Context context, List<Customize> itemsList) {
this.context = context;
this.itemsList = itemsList;
pagerAdapter = new TabsPagerAdapter(((AppCompatActivity)context).getSupportFragmentManager());
}
@Override
public PrefsCustomizeViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.prefs_customize_items_layout, parent, false);
return new PrefsCustomizeViewHolder(view);
}
@Override
public void onBindViewHolder(final PrefsCustomizeViewHolder viewholder, final int position) {
final Customize customize = itemsList.get(position);
Picasso.with(context)
.load(customize.getIcon())
.fit()
.into(viewholder.prefsSelImg);
// search db to find if checkbox is checked, i.e tab is present or not and update recyclerview
switch (position) {
case 0:
cust = new Select()
.from(Customize.class)
.where("tabName = ? ", Constants.SPACE)
.executeSingle();
if (cust != null) {
space = cust.tabName;
Log.d(TAG, "Space Tab From DB:\t" + space);
id_space = cust.getId();
Log.d(TAG, "Space Tab Id from DB:\t" + id_space);
viewholder.prefsCheckBox.setChecked(true);
} else {
viewholder.prefsCheckBox.setVisibility(View.INVISIBLE);
viewholder.prefsCheckBox.setChecked(false);
}
break;
}
viewholder.prefsSelImg.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
switch (position) {
case 0:
if (viewholder.prefsCheckBox.isChecked()){
viewholder.prefsCheckBox.setChecked(false);
Customize.delete(Customize.class, id_space);
Log.d(TAG, "Deleted Space id:\t" + id_space); // prints right log detail
pagerAdapter.removeTab(new SpaceFragment(), Constants.SPACE);
} else {
viewholder.prefsCheckBox.setChecked(true);
customize.setTabId(UUID.randomUUID().toString());
customize.setTabName(Constants.NATURE);
customize.save();
pagerAdapter.addTab(new SpaceFragment(), Constants.SPACE);
viewholder.prefsCheckBox.setVisibility(View.VISIBLE);
}
break;
}
}
});
}
@Override
public int getItemCount() {
if (itemsList == null) {
return 0;
}
return itemsList.size();
}
}
tabspagerAdapter.removeTab() 永远不会被调用，即使我已经在下面的构造函数中对其进行了初始化：
public PrefsAdapter(Context context, List<Customize> itemsList) {
this.context = context;
this.itemsList = itemsList;
pagerAdapter = new TabsPagerAdapter(((AppCompatActivity)context).getSupportFragmentManager());
}
有人可以帮我删除片段，以及为什么永远不会调用 pagerAdapter.removeTab(fragment, title) 方法以及如何更新选项卡布局。谢谢。
【问题讨论】：
标签： android android-fragments android-viewpager android-recyclerview android-tablayout