FragmentPagerAdapter 动态更新标题

Question

I have a ViewPager with FragmentPagerAdapter, which has 3 Fragments. Now, I have a number of items as part of the title of the fragment:

So user can add or remove those items, and title should update accordingly. However, this title seems static.

How can one recall this method to update FragmentPagerAdapter's titles?

@Override
    public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0: return items + " (" + notFoundItems + ")";
            case 1: return found;
            case 2: return review;
        }
        return "";
    }

I found a couple of similar questions on SO, but I need to update title , not only the fragment itself.

Answer 1

Finally, I solved it by simply re-setting the pager.

private OrdersTabsAdapter tabsAdapter;
@InjectView(R.id.tabs_orders) SlidingTabLayout ordersTabs;
@InjectView(R.id.pager) ViewPager pager;

public void update() {
  tabsAdapter.updateFragments(productId, status);
  ordersTabs.setViewPager(pager); //this helped with the titles
}

Answer 2

As one of the comments beneath it suggests, the accepted answer looks a bit overkill to me.

Based on Frank's answer , this is what I have done:

public void myUpdatePageTitle(int pagePosition, int numItems) {
    TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
    TabLayout.Tab tab = tabLayout.getTabAt(pagePosition);
    if (tab != null) {
        tab.setText(myCalcTabTitle(pagePosition, numItems));
    }
}

private String myCalcTabTitle(int pagePosition, int numItems) {
    //TODO - For this page, return whatever title string you like, including the numItems value. (The best way to do this is using a string resource that accepts a decimal parameter.)
}

Answer 3

Okay. So you can have a method in FragmentPagerAdapter that will update the count for notFoundItems , foundItems , itemsForReview . After you update them, call the notifyDataSetChanged() .

 @Override
 public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0: return items + " (" + notFoundItems + ")";
            case 1: return found + " (" + foundItems + ")";
            case 2: return review + " (" + itemsForReview + ")";
        }
        return "";
 }

Also, add this to the your implementation of FragmentPagerAdapter class. So whenever you have a new data count and want to update the title, call this method.

 public void updateTitleData(int notFoundItems, int foundItems, int itemsForReview) {
      this.notFoundItems = notFoundItems;
      this.foundItems = foundItems;
      this.itemsForReview = itemsForReview;
      notifyDataSetChanged();
 }

Answer 4

you have 3 fragments so you will use 3 tabs(first tab hav index 0,second 1,third 2). get your tab using index and set her text as title. May this help you bro

Example:

TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
tabLayout.getTabAt(index).setText("");

Answer 5

I don't think reset ViewPager and notifyDataSetChange is a good idea. Because it will cause the view in ViewPager to recreate. It's unnecessary.

And i found another way to solve the problem.

    List<OrderListResult.TradeStatusVOsEntity> tradeStatusVOs = updateTitleEvent.getTradeStatusVOs();
    for (int i = 0; i < tradeStatusVOs.size(); i++) {
        OrderListResult.TradeStatusVOsEntity tradeStatusVOsEntity = tradeStatusVOs.get(i);
        int num = tradeStatusVOsEntity.getNum();
        String text = mAdapter.getPageTitle(i).toString();
        if (num > 0) {
            text = text + "(" + num + ")";
        }
        mButterTabs.getTabAt(i).setText(text);
    }

    mButterTabs.setTabTextColors(getResources().getColor(android.R.color.darker_gray),
            getResources().getColor(R.color.yellow));

First, you need to use getTabAt method of TabLayout to change the model of tab. Then call setTabTextColors to update view. Because from the source code of TabLayout, setTabTextColors will update all tabs one by one.

Answer 6

There is no point in your re setting your pager each time.
You've already got getPageTitle() overridden and you are just missing to track when your pages are changed and when is the time to update the title.
So you can easily do this:

viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
    @Override
    public void onPageSelected(int position) {
        // your tite is: mAdapter.getPageTitle(position));
        // TODO: update title
    }
});

Also you will have to set initial title in onCreate()

Answer 7

TabLayout.OnTabSelectedListener will be triggered when re-setup with the ViewPager , so I recommend update the title by self.

viewPager.adapter?.apply {
    for (p in 0..count) {
        tabLayout.getTabAt(p)?.text = getPageTitle(p) ?: break
    }
}