Question

我知道这个问题可能很奇怪，但是请在按下大拇指按钮之前先听我说。

我有TabLayout个带有自定义视图的两个标签，并且我做了一切正确的操作，直到我想更改自定义标签视图（无论是否被选中）为止，基本上，我希望它使所选视图的alpha = 1且未选中= 0.3f。

我找到了一种方法，并且只有在应用程序语言为英语时，它才可以正常运行。但是。当我将其更改为阿拉伯语这样的RTL语言时，当我使用NullPointerException时，获取自定义标签视图。

代码 （检查注释）

private void initTabs() {

    adapter = new TabsPagerAdapter(getFragmentManager());
    viewpager.setAdapter(adapter);
    tabs.setupWithViewPager(viewpager);

    for (int i = 0; i < tabs.getTabCount(); i++) {
        TabLayout.Tab tab = tabs.getTabAt(i);
        tab.setCustomView(adapter.getTabView(i));
    }

    adapter.SetOnSelectView(tabs, 0); // this makes the first tab as selected 

    tabs.addOnTabSelectedListener(new TabLayout.BaseOnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {
            int c = tab.getPosition();
            adapter.SetOnSelectView(tabs, c);
        }

        @Override
        public void onTabUnselected(TabLayout.Tab tab) {
            int c = tab.getPosition();
            adapter.SetUnSelectView(tabs, c);
        }

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

        }
    });

}



public class TabsPagerAdapter extends FragmentPagerAdapter {

    private String tabTitles[] = new String[]{getString(R.string.tab1), getString(R.string.tab2)};
    LinearLayout main;

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

    public View getTabView(int position) {
        View v = LayoutInflater.from(getActivity()).inflate(R.layout.tab_custom, null);
        main = v.findViewById(R.id.main_view);
        TextView title_tv = v.findViewById(R.id.tab_title_tv);
        TextView services_tv = v.findViewById(R.id.services_num);
        TextView products_tv = v.findViewById(R.id.products_num);
        title_tv.setText(tabTitles[position]);
        services_tv.setText("3 " + getString(R.string.services));
        products_tv.setText("4 " + getString(R.string.products));

        return v;
    }

    public void SetOnSelectView(TabLayout tabLayout, int position) {

        try {
            TabLayout.Tab tab = tabLayout.getTabAt(position);
            // NPE here due getCustomView == null only when locale == ar 
            View selected = tab.getCustomView();
            LinearLayout main = selected.findViewById(R.id.main_view);
            main.setAlpha(1);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    public void SetUnSelectView(TabLayout tabLayout, int position) {
        try {
            TabLayout.Tab tab = tabLayout.getTabAt(position);
            View selected = tab.getCustomView();
            LinearLayout main = selected.findViewById(R.id.main_view);
            main.setAlpha(0.3f);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    @Override
    public Fragment getItem(int i) {
        return new TabDeatilsFragment();
    }

    @Override
    public int getCount() {
        return tabTitles.length;
    }
}

Logcat

java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
    at com._Fragment$TabsPagerAdapter.SetOnSelectView(_Fragment.java:156)
    at com._Fragment$1.onTabSelected(OrderDetails_Fragment.java:88)
    at android.support.design.widget.TabLayout.dispatchTabSelected(TabLayout.java:1608)
    at android.support.design.widget.TabLayout.selectTab(TabLayout.java:1601)
    at android.support.design.widget.TabLayout.selectTab(TabLayout.java:1569)
    at android.support.design.widget.TabLayout.populateFromPagerAdapter(TabLayout.java:1330)
    at android.support.design.widget.TabLayout$PagerAdapterObserver.onChanged(TabLayout.java:2850)
    at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:37)
    at android.support.v4.view.PagerAdapter.notifyDataSetChanged(PagerAdapter.java:294)
    at com.duolingo.open.rtlviewpager.DelegatingPagerAdapter.notifyDataSetChanged(DelegatingPagerAdapter.java:106)
    at com.duolingo.open.rtlviewpager.RtlViewPager.onRtlPropertiesChanged(RtlViewPager.java:67)

Answer 1

我遇到了同样的问题，就解决了。

您的问题是，当调用notifyDataSetChanged时，所有以前的CustomViews都被重置了

您需要检查SetOnSelectView（）中的自定义视图是否为空，然后在notifyDataSetChanged之后重新分配customViews。

希望这会有所帮助

语言更改后，自定义选项卡布局为null

1 个答案: