java - Android Studio错误 "cannot resolve method"

Question

我的应用程序的 Java 代码遇到问题

        @Override
        public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) 
        {
            Message message = dataSnapshot.getValue(Message.class);
            message.setKey(dataSnapshot.getKey());
            messages.add(message);
            displayMessages(messages);
        }

抛出错误:"cannot resolve method"

Answer 1

我认为您缺少一些东西，请尝试以下代码:

ref.addChildEventListener(new ChildEventListener() {
  @Override
  public void onChildAdded(DataSnapshot dataSnapshot, String prevChildKey) {
    Post newPost = dataSnapshot.getValue(Post.class);
    System.out.println("Author: " + newPost.author);
    System.out.println("Title: " + newPost.title);
    System.out.println("Previous Post ID: " + prevChildKey);
  }

  @Override
  public void onChildChanged(DataSnapshot dataSnapshot, String prevChildKey) {}

  @Override
  public void onChildRemoved(DataSnapshot dataSnapshot) {}

  @Override
  public void onChildMoved(DataSnapshot dataSnapshot, String prevChildKey) {}

  @Override
  public void onCancelled(DatabaseError databaseError) {}
});