从一个片段滑动到另一个片段时调用方法答案

【问题标题】：Call a method when sliding from one fragment to another从一个片段滑动到另一个片段时调用方法
【发布时间】：2018-01-31 14:44:05
【问题描述】：

我在ViewPager 和Activity 中有2 个标签为fragments

当我点击布局中的第二个选项卡时，OnTabUnselected 方法有效。

但是，当我将屏幕从一个选项卡滑动到另一个选项卡时，不会调用该方法。

我如何通过“点击以及滑动手势”两种方式实现这种方法调用

我的活动课程是：

public class OrderActivity extends AppCompatActivity {

    private Toolbar toolbar;
    private TabLayout tabLayout;
    private ViewPager viewPager;
    private FloatingActionButton printAction;
    ViewPagerAdapter adapter;
    private Boolean exit = false;

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

        TypefaceUtil.overrideFont(getApplicationContext(), "serif", "fonts/opensans.tff");
        //TypefaceUtil.overrideFont(getApplicationContext(), "arial", "fonts/opensans.tff");

        this.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        viewPager = (ViewPager) findViewById(R.id.viewpager);
        setupViewPager(viewPager);

        tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);
        //setupTabIcons();
        printAction = (FloatingActionButton) findViewById(R.id.float_print); 

        tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                Toast.makeText(getApplicationContext(),"onTabSelected",Toast.LENGTH_LONG).show();
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {
                String ac = null;
                int pos = viewPager.getCurrentItem();
                Fragment activeFragment = adapter.getItem(pos);
                if(pos==0){
                   ac=  ((PersonalDetailFragment)activeFragment).getXmlValue();
                }

                Toast.makeText(getApplicationContext(),ac,Toast.LENGTH_LONG).show();
            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {
                Toast.makeText(getApplicationContext(),"onTabReselected",Toast.LENGTH_LONG).show();
            }
        });


    }


    private void setupViewPager(ViewPager viewPager) {
        adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFrag(new PersonalDetailFragment(), "Personal");
        adapter.addFrag(new OrderItemsFragment(), "Invoice");
        viewPager.setAdapter(adapter);
    }



    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();

        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }

        @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);
        }
    }

}

片段 A：

 public class FragmentA extends Fragment {

        private EditText custName; 
        public PersonalDetailFragment() {
            // Required empty public constructor
        }

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            // Inflate the layout for this fragment

            View view = inflater.inflate(R.layout.personal_detail_fragment, container, false); 
            custName = (EditText) view.findViewById(R.id.customerContactEditText); 

            return view;
        }  


public String getXmlValue(){

        return custName.getText().toString();
    }

    }

片段 B：

public class FragmentB extends Fragment {

    private EditText contactNo; 
    public PersonalDetailFragment() {
        // Required empty public constructor
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment

        View view = inflater.inflate(R.layout.personal_detail_fragment, container, false); 
        contactNo = (EditText) view.findViewById(R.id.customerContactEditText); 

        return view;
    }  

}

【问题讨论】：

标签： android android-fragments android-viewpager android-tablayout

【解决方案1】：

您可以使用ViewPager.addOnPageChangeListener() 方法注册一个侦听器并获得有关通过寻呼机滑动更改当前选项卡的通知。

有一个非常好的教程here。

【讨论】：

【解决方案2】：

在您的片段中，您可以使用名为setVisibilityHint 的方法，每次更改片段的可见性时都会调用该方法。有一个布尔参数可以是true 或false，具体取决于片段是否可见

@Override
    public void setUserVisibleHint(boolean isVisibleToUser) {
        super.setUserVisibleHint(isVisibleToUser);
    }

【讨论】：