如何为Viewpager片段设置标签? [英] How can i set a tag for viewpager fragments?

问题描述

I，m使用带有4个选项卡的slideTabLayout以及每个选项卡的viewpager和4个片段类.

I,m using slidingTabLayout with 4 tabs and a viewpager and 4 fragment class for every tab.

当用户单击某个按钮时，我需要在我的项目中重新加载一个片段(第一个选项卡)，为此，我需要为该片段添加一个标签

i need to reload one of my fragments (first tab) in my project when user click some button, and for this i need to have a tag for that fragment

我的问题是:如何为viewpagers片段之一设置标签?

my question is : how can i set a tag for one of viewpagers fragment???

我的MainActivity"标签和Viewpager代码:

My MainActivity tab and viewpager codes:

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {



Toolbar toolbar;
ViewPager pager;
ViewPagerAdapter adapter;
SlidingTabLayout tabs;
CharSequence Titles[]={"نوع","قیمت","برند","همه"};
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, "درج آگهی رایگان", 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

推荐答案

有两种解决方案.

1).当FragmentPagerAdapter在FragmentManager上添加Fragment时，它会根据放置Fragment的特定位置使用特殊标记.因此，您只需使用这些代码行即可在ViewPager中获得当前可见的Fragment

1). When the FragmentPagerAdapter adds a Fragment to the FragmentManager, it uses a special tag based on the particular position that the Fragment will be placed. So you can simply get the current visible Fragment in your ViewPager using these lines of code

 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FragmentStatePagerAdapter中的所有活动片段.对于演示示例，您可以参考第二种方法此处

2). You should keep track of all the active fragments in the FragmentStatePagerAdapter. For demo sample you can refer to second approach here

3).您可以使用EventBus从任何地方将事件发布到Fragment中.您要做的就是为该特定事件注册您的Fragment.有关官方文档，请参见此

3). You can make use of EventBus to post events to your Fragment from anywhere. All you have to do is to register your Fragment for that specific event. For official documentation refer this

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