如何为viewpager片段设置标记？

Question

我,使用带有4个选项卡的slidingTabLayout和每个选项卡的viewpager和4个片段类.

当用户点击某个按钮时,我需要在我的项目中重新加载我的一个片段(第一个标签),为此我需要为该片段添加一个标签

我的问题是:如何为其中一个viewpagers片段设置一个标签???

我的MainActivity选项卡和viewpager代码:

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {



Toolbar toolbar;
ViewPager pager;
ViewPagerAdapter adapter;
SlidingTabLayout tabs;
CharSequence Titles[]={"???","????","????","???"};
int Numboftabs = 4;




@Override
protected void attachBaseContext(Context newBase) {
    super.attachBaseContext(CalligraphyContextWrapper.wrap(newBase));
}



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);




    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "??? ???? ??????", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });



    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);

    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);




    // Creating The ViewPagerAdapter and Passing Fragment Manager, Titles fot the Tabs and Number Of Tabs.
    adapter =  new ViewPagerAdapter(getSupportFragmentManager(),Titles,Numboftabs);

    // Assigning ViewPager View and setting the adapter
    pager = (ViewPager) findViewById(R.id.pager);
    pager.setAdapter(adapter);

    // Assiging the Sliding Tab Layout View
    tabs = (SlidingTabLayout) findViewById(R.id.tabs);
    tabs.setDistributeEvenly(true); // To make the Tabs Fixed set this true, This makes the tabs Space Evenly in Available width

    // Setting Custom Color for the Scroll bar indicator of the Tab View
    tabs.setCustomTabColorizer(new SlidingTabLayout.TabColorizer() {
        @Override
        public int getIndicatorColor(int position) {
            return getResources().getColor(R.color.colorWhite);
        }
    });

    // Setting the ViewPager For the SlidingTabsLayout
    tabs.setViewPager(pager);
    pager.setCurrentItem(3);




} and ....

非常感谢

Answer 1

对此有几种解决方案.

1).当FragmentPagerAdapter添加a Fragment时FragmentManager,它Fragment会根据将要放置的特定位置使用特殊标记.所以,你可以简单地得到当前可见Fragment您在ViewPager使用这些代码

 Fragment fragment = getSupportFragmentManager().findFragmentByTag("android:switcher:" + R.id.pager + ":" + ViewPager.getCurrentItem());
 // based on the current position you can then cast the page to the correct Fragment class and call some method inside that fragment to reload the data:
 if (0 == ViewPager.getCurrentItem() && null != fragment) {
      ((TabFragment1)fragment).reloadFragmentData();     
 } 

2).您应该跟踪中的所有活动片段FragmentStatePagerAdapter.对于演示示例,您可以在此处参考第二种方法

3).您可以利用从任何EventBus地方向您发布活动Fragment.您所要做的就是注册您Fragment的特定活动.有关官方文档,请参阅此

Answer 2

以下是用于FragmentPagerAdapter创建Fragment标记名称的方法:

private static String makeFragmentName(int viewId, long id) {
    return "android:switcher:" + viewId + ":" + id;
}

viewId是的id ViewPager.
id是片段里面的位置ViewPager.

例:

String fragmentTag = makeFragmentName(myViewPager.getId(), 2);
Fragment fragment = getSupportFragmentManager().findFragmentByTag(fragmentTag);