Question

解释，我使用viewpager类进行2个活动。当您单击ActivityMainTab列表中的某个项目时，它将被带到另一个活动（ActivityAtTab），它还使用与前一个相同的viewpager类来生成其选项卡和片段。

我需要知道Conduit片段是否在屏幕上，所以在我将在下面显示的条件下，我可以转到正确的方法并继续流程。

代码下方：

ActivityAtTab，此方法检查屏幕上的哪个片段，以便匹配变量转到正确的showResults。在mFragmentConduit的情况下，我无法判断它是否在屏幕上，因为它来自viewPager。 ActivityAtTab

@Override
public void onResults(Bundle results) {

    //inicializando as variáveis de fragments
    av = (FragmentAv) getSupportFragmentManager().findFragmentByTag(getString(R.string.tag_fragment_av));
    rec = (FragmentRec) getSupportFragmentManager().findFragmentByTag(getString(R.string.tag_fragment_rec));
    ex = (FragmentEx) getSupportFragmentManager().findFragmentByTag(getString(R.string.tag_fragment_ex));
    enc = (FragmentEnc) getSupportFragmentManager().findFragmentByTag(getString(R.string.tag_fragment_enc));
    atest = (FragmentAtest) getSupportFragmentManager().findFragmentByTag(getString(R.string.tag_fragment_atest));
    dig = (FragmentDiag) getSupportFragmentManager().findFragmentByTag(getString(R.string.tag_fragment_diag));
    mFragmentConduit = (FragmentConduit) getSupportFragmentManager().findFragmentByTag(getString(R.string.tag_fragment_conduit));

    //pegando a lista de comandos
    ArrayList<String> matches = results
            .getStringArrayList(SpeechRecognizer.RESULTS_RECOGNITION);

    //Verifica qual fragment está chamando a interface
    //e passa o valor da string para que seja implementada nos respectivos campos.
    try {
        if (av != null && av instanceof ResultFragmentsConduit) {
            resultFragmentsConduit = av;
            resultFragmentsConduit.showCondutaResults(matches);
        } else if (rec != null && rec instanceof ResultFragmentsConduit) {
            ResultFragmentsConduit = rec;
            ResultFragmentsConduit.showCondutaResults(matches);
        } else if (ex != null && ex instanceof ResultFragmentsConduit) {
            ResultFragmentsConduit = ex;
            ResultFragmentsConduit.showCondutaResults(matches);
        } else if (enc != null && enc instanceof ResultFragmentsConduit) {
            ResultFragmentsConduit = enc;
            ResultFragmentsConduit.showCondutaResults(matches);
        } else if (at != null && at instanceof ResultFragmentsConduit) {
            ResultFragmentsConduit = at;
            ResultFragmentsConduit.showCondutaResults(matches);
        } else if (dig != null && dig instanceof ResultFragmentsConduit) {
            ResultFragmentsConduit = dig;
            ResultFragmentsConduit.showCondutaResults(matches);
        } else if (mFragmentConduit != null && mFragmentConduit.isVisible() ){ //ALWAYS NULL!!!!!!!!!
            showResultsConduit(matches);
        }
    } catch (Exception e) {
        e.getStackTrace();
        Log.e(TAG_TABATENDIMENTO, e.getMessage());
    }
}

ActivityAtTab的onCreate方法，其中片段在viewPager中提交构造：

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_atendimento_tab);

        //TODO FRAGMENTOS
        mFragmentsArrayList = new ArrayList<>();
        mFragmentsArrayList.add(mFragmentConduit = new FragmentConduit());
        mFragmentsArrayList.add(new FragmentHistorico());

        stringArrayListTitleFragment = new ArrayList<>();
        stringArrayListTitleFragment.add(getString(R.string.fragment_conduit));
        stringArrayListTitleFragment.add(getString(R.string.fragment_historico));

        mCustomTabLayout = new CustomTabLayout(this, mFragmentsArrayList, stringArrayListTitleFragment);

        requestPermission();
    }

ViewPager：

public class CustomTabLayout {

    public AppCompatActivity mAppCompatActivity;
    private TabLayout tabLayout;
    private ViewPager viewPager;
    private PagerAdapter adapter;
    private ArrayList<Fragment> mFragmentArrayList;
    private ArrayList<String> mFragmentArrayListTitle;

    public CustomTabLayout(AppCompatActivity appCompatActivity, ArrayList<Fragment> fragments, ArrayList<String> stringArrayListFragments) {

        mAppCompatActivity = appCompatActivity;

        mFragmentArrayList = fragments;
        mFragmentArrayListTitle = stringArrayListFragments;

        viewPager = mAppCompatActivity.findViewById(R.id.viewpager);

        tabLayout = mAppCompatActivity.findViewById(R.id.tabs);

        createViewPager(viewPager);

        tabLayout.setupWithViewPager(viewPager);

        tabLayout.setOnTabSelectedListener(adapter);

        createTabIcons();
    }

    private void createViewPager(ViewPager viewPager) {

        adapter = new PagerAdapter(mAppCompatActivity.getSupportFragmentManager());

        for (int contador = 0; contador < mFragmentArrayList.size(); contador++) {

            adapter.addFrag(mFragmentArrayList.get(contador), mFragmentArrayListTitle.get(contador));
        }

        viewPager.setAdapter(adapter);
    }

    class PagerAdapter extends FragmentStatePagerAdapter implements TabLayout.OnTabSelectedListener {

        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();

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

        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }

        @Override
        public int getCount() {
            return mFragmentList.size();
        }

        public void addFrag(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
        }

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

            LinearLayout linearLayoutAnimation = (LinearLayout) tab.getCustomView().findViewById(R.id.custom_tab_linear_layout_animation);

            linearLayoutAnimation.setVisibility(View.VISIBLE);

            linearLayoutAnimation.setBackground(ContextCompat.getDrawable(mAppCompatActivity, R.drawable.aba_grande));

            Animation bottomUp = AnimationUtils.loadAnimation(mAppCompatActivity,
                    R.anim.bottom_up);

            linearLayoutAnimation.startAnimation(bottomUp);

            //TODO CHAMA ACTIVITY
        }


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

            final LinearLayout linearLayoutAnimation = (LinearLayout) tab.getCustomView().findViewById(R.id.custom_tab_linear_layout_animation);

            Animation bottomDown = AnimationUtils.loadAnimation(mAppCompatActivity,
                    R.anim.bottom_down);

            bottomDown.setAnimationListener(new Animation.AnimationListener() {
                @Override
                public void onAnimationStart(Animation animation) {

                }

                @Override
                public void onAnimationEnd(Animation animation) {
                    linearLayoutAnimation.setVisibility(View.GONE);
                }

                @Override
                public void onAnimationRepeat(Animation animation) {

                }
            });

            linearLayoutAnimation.startAnimation(bottomDown);

        }

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


        }
    }

    private void createTabIcons() {

        for (int contador = 0; contador < mFragmentArrayList.size(); contador++) {

            LinearLayout tabCustom = (LinearLayout) LayoutInflater.from(mAppCompatActivity).inflate(R.layout.custom_tab, null);
            TextView textViewTabCustom = tabCustom.findViewById(R.id.custom_tab_title);
            textViewTabCustom.setText(mFragmentArrayListTitle.get(contador));
            tabLayout.getTabAt(contador).setCustomView(tabCustom);
        }
    }

    /**
     *
     */
    public void selectTabInitialTab() {

        LinearLayout linearLayoutRoot = (LinearLayout) tabLayout.getTabAt(0).getCustomView().findViewById(R.id.custom_tab_linear_layout_animation);

        linearLayoutRoot.setBackground(ContextCompat.getDrawable(mAppCompatActivity, R.drawable.aba_grande));

        Animation bottomUp = AnimationUtils.loadAnimation(mAppCompatActivity,
                R.anim.bottom_up);

        linearLayoutRoot.startAnimation(bottomUp);
    }
}

在activityattab中，Conduit片段始终是第一个创建的，位置0。我不能用TAG来搜索这个片段。

Answer 1

在CustomTabLayout内添加

tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener()
            {
                @Override
                public void onTabSelected(TabLayout.Tab tab)
                {
                    int position = tab.getPosition();


                }

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

                }
            });

Answer 2

您可以使用以下方式获取当前可见片段。它会让你回到原位。

viewPager.getCurrentItem();

Answer 3

在您的活动中，您可以这样检查： -

PermissionRule

Answer 4

使用此：

Fragment f = getSupportFragmentManager().findFragmentByTag("android:switcher:" + R.id.viewPager + ":" + viewPager.getCurrentItem());
if (f instanceof FragmentA) {
} else {
}

如何在viewpager中获取当前片段名称？

4 个答案: