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我试图通过一个字符串“mMeetingKey”从View.class到PostListFragment.class，但该包返回null。我检查了View.class中的包，它不是null。当我检查PostListFragment.class中的包时，它会一直返回null。片段活动，getArgument返回null
该代码主要来自“Firebase Quickstart for Database”。
谢谢你的帮助。
View.class
public class View extends BaseActivity {
private FragmentPagerAdapter mPagerAdapter;
private ViewPager mViewPager;
private String mMeetingKey;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_posts);
mViewPager = findViewById(R.id.container);
mMeetingKey=getIntent().getStringExtra("meetingKey");
Bundle bundle = new Bundle();
bundle.putString("mMeetingKey", mMeetingKey);
PostListFragment postListFragment=new PostListFragment();
postListFragment.setArguments(bundle);
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.container,postListFragment).commit();
mPagerAdapter = new FragmentPagerAdapter(getSupportFragmentManager()) {
private final Fragment[] mFragments = new Fragment[] {
new PostListFragment(),
// new MyPostsFragment(),
// new CompletedPostFragment(),
};
private final String[] mFragmentNames = new String[] {
getString(R.string.heading_recent),
//getString(R.string.heading_my_posts),
//getString(R.string.heading_completed_posts)
};
@Override
public Fragment getItem(int position) {
return mFragments[position];
}
@Override
public int getCount() {
return mFragments.length;
}
@Override
public CharSequence getPageTitle(int position) {
return mFragmentNames[position];
}
};
mViewPager.setAdapter(mPagerAdapter);
TabLayout tabLayout = findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
Toast.makeText(this,mMeetingKey,Toast.LENGTH_LONG).show();
// Button launches NewPostActivity
findViewById(R.id.fab_new_post).setOnClickListener(new android.view.View.OnClickListener() {
@Override
public void onClick(android.view.View v) {
Intent intent = new Intent(View.this, NewPostActivity.class);
intent.putExtra("mMeetingKey",mMeetingKey);
startActivity(intent);
}
});
}
}
PostListFragment.class
public class PostListFragment extends android.support.v4.app.Fragment {
private static final String TAG = "PostListFragment";
// [START define_database_reference]
private DatabaseReference mDatabase;
// [END define_database_reference]
private String mMeetingKey;
private FirebaseRecyclerAdapter<Post, PostViewHolder> mAdapter;
private RecyclerView mRecycler;
private String meetingKeyRef;
private LinearLayoutManager mManager;
public PostListFragment() {}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView (LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
View rootView = inflater.inflate(R.layout.fragment_all_post, container, false);
Bundle bundle = this.getArguments();
if (bundle != null) {
meetingKeyRef = bundle.getString("mMeetingKey").toString();
}
if (bundle!= null) {
meetingKeyRef = this.getArguments().getString("mMeetingKey");
}
if (bundle == null) {
throw new IllegalArgumentException("Bundle is null");
}
// [START create_database_reference]
mDatabase = FirebaseDatabase.getInstance().getReference().child(meetingKeyRef);
// [END create_database_reference]
mRecycler = rootView.findViewById(R.id.messages_list);
mRecycler.setHasFixedSize(true);
return rootView;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// Set up Layout Manager, reverse layout
mManager = new LinearLayoutManager(getActivity());
mManager.setReverseLayout(true);
mManager.setStackFromEnd(true);
mRecycler.setLayoutManager(mManager);
// Set up FirebaseRecyclerAdapter with the Query
Query postsQuery = getQuery(mDatabase);
mAdapter = new FirebaseRecyclerAdapter<Post, PostViewHolder>(Post.class, R.layout.item_post,
PostViewHolder.class, postsQuery) {
@Override
protected void populateViewHolder(final PostViewHolder viewHolder, final Post model, final int position) {
final DatabaseReference postRef = getRef(position);
mMeetingKey= postRef.getKey();
// Set click listener for the whole post view
final String postKey = postRef.child(mMeetingKey).getKey();
viewHolder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// Launch PostDetailActivity
Intent intent = new Intent(getActivity(), PostDetailActivity.class);
intent.putExtra(PostDetailActivity.EXTRA_POST_KEY, postKey);
intent.putExtra(PostDetailActivity.EXTRA_MEETING_KEY,mMeetingKey);
startActivity(intent);
}
});
// Determine if the current user has liked this post and set UI accordingly
if (model.boxCount==1) {
viewHolder.boxView.setImageResource(R.drawable.ic_toggle_check_box_checked);
} else {
viewHolder.boxView.setImageResource(R.drawable.ic_toggle_check_box_outline);
}
// Bind Post to ViewHolder, setting OnClickListener for the star button
viewHolder.bindToPost(model, new View.OnClickListener() {
@Override
public void onClick(View boxView) {
// Need to write to both places the post is stored
DatabaseReference globalPostRef = mDatabase.child("posts").child(postRef.getKey());
DatabaseReference userPostRef = mDatabase.child("user-posts").child(model.uid).child(postRef.getKey());
// Run two transactions
onBoxClicked(globalPostRef);
onBoxClicked(userPostRef);
}
});
}
};
mRecycler.setAdapter(mAdapter);
}
// [START post_stars_transaction]
private void onBoxClicked(DatabaseReference postRef) {
postRef.runTransaction(new Transaction.Handler() {
@Override
public Transaction.Result doTransaction(MutableData mutableData) {
Post p = mutableData.getValue(Post.class);
if (p == null) {
return Transaction.success(mutableData);
}
if (p.checkbox.containsKey(getUid())) {
// Unstar the post and remove self from stars
p.boxCount = 0;
p.checkbox.remove(getUid());
} else {
// Star the post and add self to stars
p.boxCount = 1;
p.checkbox.put(getUid(), true);
}
// Set value and report transaction success
mutableData.setValue(p);
return Transaction.success(mutableData);
}
@Override
public void onComplete(DatabaseError databaseError, boolean b,
DataSnapshot dataSnapshot) {
// Transaction completed
Log.d(TAG, "postTransaction:onComplete:" + databaseError);
}
});
}
// [END post_stars_transaction]
@Override
public void onDestroy() {
super.onDestroy();
if (mAdapter != null) {
mAdapter.cleanup();
}
}
public String getUid() {
return FirebaseAuth.getInstance().getCurrentUser().getUid();
}
public Query getQuery(DatabaseReference databaseReference){
Query recentPostsQuery = databaseReference.child("posts")
.limitToFirst(100);
// [END recent_posts_query]
return recentPostsQuery;
}
}
activity_view_posts.xml
<?xml version="1.0" encoding="utf-8"?>
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.design.widget.TabLayout
android:id="@+id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<android.support.v4.view.ViewPager
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@id/tabs"/>
<android.support.design.widget.FloatingActionButton
android:id="@+id/fab_new_post"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_margin="16dp"
android:src="@drawable/ic_create"
app:backgroundTint="@android:color/holo_orange_dark" />
fragment_all_post.xml
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".checklist.View">
<android.support.v7.widget.RecyclerView
android:id="@+id/messages_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentTop="true"
android:clipToPadding="false"
android:padding="5dp"
android:scrollbars="vertical"
tools:listitem="@layout/item_post" />
https://stackoverflow.com/questions/14727759/send-values-from-viewpager-activity-to-a-fragment-by-bundle –