java–什么是notifyItemRangeChanged(0,this.data.size());在这个例子中,它是如何工作的？

我理解ViewHolder的onBindViewHolder如何工作,但是我不清楚notifyItemRangeChanged(0,this.data.size())如何;适用于此示例以及它的确切功能.

提供给此适配器的数据采用Json格式.

适配器如下：

public class AdapterQuestion extends RecyclerView.Adapter{
private LayoutInflater mLayoutInflater;
//this is an arrayList of questionData objects
private ArrayList data =new ArrayList<>();
//Created the layoutInflator
public AdapterQuestion(Context context){
//get from context
mLayoutInflater=LayoutInflater.from(context);
}
public void setBloglist(ArrayList data){
this.data =data;
notifyItemRangeChanged(0, this.data.size());
}
@Override
public ViewQuestion onCreateViewHolder(ViewGroup parent, int viewType) {
//inflates the customQuestion view or converts it to java code
View view= mLayoutInflater.inflate(R.layout.customquestion, null);
//We now want to convert the View into a ViewQuestion, view Question takes
//a view so we pass the view into view question and then return it.
ViewQuestion holder=new ViewQuestion(view);
return holder;
}
//ViewGroup parent and ViewType are not being assigned.
@Override
public void onBindViewHolder(ViewQuestion holder, int position) {
//here we need to bind the data to our view, there is currently no Data!
//We need to get the data from our JSON
//Parameters is a ViewHolder and a Position
//This gives us the current information object from the whole arraylist
//data.get(position) data is the arraylist and we are getting the current position or index;
//That current obj is of Type QuestionData
QuestionData currentObj= data.get(position);
//we are accessing the Inflated view, or saved view with holder
//holder.answerText is the textView in holder. We are then taking that current object
//We are getting the text of the current object and setting it to the AnswerText view
holder.answerText.setText(currentObj.getMtext());
holder.answerId.setText(currentObj.getId());
holder.mVotes.setText(currentObj.getVotes());
holder.mLikeButton.setTag(currentObj);
}
@Override
public int getItemCount() {
return data.size();
}
public class ViewQuestion extends RecyclerView.ViewHolder{
//once we create it once the reclycer view will automatically recycle it
private TextView answerText;
private TextView answerId;
private TextView mVotes;
private LikeButton mLikeButton;
public ViewQuestion (View itemView){
super(itemView);
//here we are finding the views by their ID
answerText=(TextView)itemView.findViewById(R.id.answerText);
answerId=(TextView)itemView.findViewById(R.id.answerId);
mVotes=(TextView)itemView.findViewById(R.id.VoteTextView);
mLikeButton= (LikeButton)itemView.findViewById(R.id.heart_buttons);
mLikeButton.setOnLikeListener(new OnLikeListener() {@Overridepublic void liked(LikeButton likeButton) { Voting vote = new Voting(); vote.onUpVote(convertToString(), getAdapterPosition(),ViewQuestion.this); System.out.print("Adapter Position"+getAdapterPosition());}@Overridepublic void unLiked(LikeButton likeButton) { Voting OnDown=new Voting(); onDown.onDownVote(convertToString(), getAdapterPosition(), ViewQuestion.this);}
});
}
public String getVoteView(){
String voteView=mVotes.getText().toString();
return voteView;
}
public String convertToString(){
String cOnverted=answerId.getText().toString();
return converted;
}
public int convertToInt(){
String cOnverted=answerId.getText().toString();
int COnvertedInt=Integer.parseInt(converted);
return ConvertedInt;
}
}
}


解决方法:

当要在RecyclerView中设置的数据发生更改时,适配器需要收到有关数据更改的通知,以便它可以更改recyclerview中的数据.

方法

notifyItemRangedChanged(fromIndex,toIndex);


用于通知适配器在整个数据中更改了一组数据,它告诉适配器适配器应刷新数据并将其重新加载到从传入方法的fromIndex到toIndex的recyclerView中.

如果您有多个数据已更改但不是全部,则使用此方法,这些已更改的数据也在群集中,以便您可以说从第5到第10个索引数据已更改.

如果更改了所有数据,请致电：

notifyDataSetChanged();


如果只更改了一个dataItem,则调用：

notifyItemChanged(dataPosition);