如何使用回调接口从Mainactivity到Fragment进行通信? [英] How to communicate from Mainactivity to Fragment using callback interface?
本文介绍了如何使用回调接口从Mainactivity到Fragment进行通信?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有一个带有四个菜单的导航抽屉，每个菜单都有自己的片段 ，第一个片段内有带有2个片段的View pager滑动标签，
I'm having navigation drawer with four menu's and each menu has own fragments , Inside first fragment has view pager sliding tab with 2 fragments,
Activity_main.xml
Activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/drawer_layout"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:fitsSystemWindows="true">
<android.support.design.widget.CoordinatorLayout
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/main_content"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.design.widget.AppBarLayout
android:id="@+id/appbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:animateLayoutChanges="true"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />
<android.support.design.widget.TabLayout
android:id="@+id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabIndicatorColor="@color/white"
app:tabIndicatorHeight="4dp" />
</android.support.design.widget.AppBarLayout>
////////////// Here I'm replacing each fragments ////////////////
<FrameLayout
android:id="@+id/main_content_framelayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior" />
<android.support.design.widget.FloatingActionButton
android:id="@+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="end|bottom"
android:layout_margin="@dimen/fab_margin"
android:src="@drawable/ic_done"
android:visibility="gone"/>
</android.support.design.widget.CoordinatorLayout>
<android.support.design.widget.NavigationView
android:id="@+id/nav_view"
android:layout_height="match_parent"
android:layout_width="wrap_content"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="@layout/nav_header"
app:menu="@menu/drawer_view"/>
</android.support.v4.widget.DrawerLayout>
ManinActivity- DrawerSelection
ManinActivity- DrawerSelection
public void selectDrawerItem(MenuItem menuItem) {
// Create a new fragment and specify the fragment to show based on nav item clicked
Fragment fragment = null;
Class fragmentClass = null;
switch (menuItem.getItemId()) {
case R.id.nav_home:
fragmentClass = Home_Tab_Fragment.class;
break;
case R.id.nav_myorders:
fragmentClass = SecondFragment.class;
break;
case R.id.nav_myoffers:
fragmentClass = ThirdFragment.class;
break;
case R.id.nav_notification:
fragmentClass = FourthFragment.class;
break;
}
fragment = (Fragment) fragmentClass.newInstance();
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.main_content_framelayout, fragment).commit();
mDrawerLayout.closeDrawers();
}
HomeTabFragment
HomeTabFragment
public class Home_Tab_Fragment extends Fragment {
private FragmentActivity myContext;
ViewPager viewPager;
TabLayout tabLayout;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.layout_viewpager, container, false);
viewPager = (ViewPager) rootView.findViewById(R.id.view_pager);
return rootView;
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
SlidingTabAdapter adapter = new SlidingTabAdapter(getChildFragmentManager());
adapter.addFragment(new FirstTabFragment(), "First TAB");
adapter.addFragment(new SecondTabFragment(), "Second Tab");
viewPager.setAdapter(adapter);
tabLayout = (TabLayout) getActivity().findViewById(R.id.tabs);
tabLayout.setVisibility(View.VISIBLE);
tabLayout.setupWithViewPager(viewPager);
}
}
SlidingTabAdapter
SlidingTabAdapter
public class SlidingTabAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragments = new ArrayList<>();
private final List<String> mFragmentTitles = new ArrayList<>();
public SlidingTabAdapter(FragmentManager fm) {
super(fm);
}
public void addFragment(Fragment fragment, String title) {
mFragments.add(fragment);
mFragmentTitles.add(title);
}
@Override
public Fragment getItem(int position) {
return mFragments.get(position);
}
@Override
public int getCount() {
return mFragments.size();
}
@Override
public CharSequence getPageTitle(int position) {
return mFragmentTitles.get(position);
}
}
layout_viewpager.xml
layout_viewpager.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/view_pager"
android:layout_width="match_parent"
android:layout_height="match_parent" />
FirstFragment
FirstFragment
public class FirstTabFragment extends Fragment {
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_first, container, false);
getActivity().setTitle("Foodies");
return rootView ;
}
public void updateFirstFragmentValues(){
//Doing some operations
}
}
在MainActivity内部，我想调用FirstTabFragment方法[updateFirstFragmentValues()]
我尝试在FirstTabFragment中添加TAG，
I tried adding TAG in FirstTabFragment ,
public static final String TAG ="FirstTabFragment.TAG";
然后我像下面那样在MainActivity中调用，但是Fragment总是为空.
Then I invoked in MainActivity like below , but Fragment always null.
public void invokeMethodFromFirstTabFragment() {
FragmentManager fm = this.getSupportFragmentManager();
FirstTabFragment fb=(FirstTabFragment)fm.findFragmentByTag(FirstTabFragment.TAG);
if (null != fb) {
fb.updateFirstFragmentValues();
}else{
L.m("Fragment is null===========");
}
}
请注意，如何从"MainActivity"内部调用"FirstTabFragment"方法
Kindly advise , How to call "FirstTabFragment" method from inside "MainActivity"
请注意，FirstTabFragment没有直接添加到MainActivity， 它是通过"Home_Tab_Fragment"添加的.
Please note FirstTabFragment is not added directly to MainActivity , its added through "Home_Tab_Fragment".
推荐答案
好了，阅读您的所有响应后，我发现您只需要在创建数据时将数据传递给片段并能够执行某些Fragment的响应即可.方法.好的，很简单:
Alright, reading all of the responses of yours, I get that you just simply need to pass data to a fragment upon creation and be able to execute some of Fragment's methods. Ok, simple enough:
public interface IMessageFragment {
/**
* Method to receive new message text
* @param text Message text to receive
*/
void updateMessageText(String text);
}
MessageFragment
public class MessageFragment extends Fragment implements IMessageFragment {
/**
* Bind views using ButterKnife
*/
@BindView(R.id.textView) TextView mTextView;
/**
* Bundle data
*/
private String mMessageText;
/**
* Unique id of bundle data
*/
private static final String MESSAGE_EXTRA_KEY = "f_message";
/**
* New fragment pattern. This is pretty much all the magic PLUS this
* looks by far better than `new Fragment()` upon instatiation
*/
public static MessageFragment newFragment(String message) {
// 1. Create new fragment
MessageFragment auctionFragment = new MessageFragment();
// 2. Create bundle for fragment params
Bundle args = new Bundle();
// 3. Put position
args.putString(MESSAGE_EXTRA_KEY, message);
// 4. Set arguments
auctionFragment.setArguments(args);
return auctionFragment;
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.tutorial_fragment, container, false);
/**
* Bind views
*/
ButterKnife.bind(this, view);
// Update UI
updateUI();
return view;
}
/**
* Method to update value of mTextView
*/
private void updateUI() {
if(!mMessageText.equals("")) {
mTextView.setText(mMessageText);
}
}
@Override
public void updateMessageText(String text) {
mMessageText = text;
updateUI();
}
}
内容非常简单，并且仅出于良好的代码风格和支持设计模式而存在接口.
Stuff is pretty simple and the interface exists only for good code style and to support design patterns.
这篇关于如何使用回调接口从Mainactivity到Fragment进行通信?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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