Java：如何在RecyclerView Adapter中为ContextCompat设置上下文？

Question

I found the solution but I still leave my question underneath. I used setBackgroundResource instead of ContextCompat , solution:

holder.mTextPar.setBackgroundResource(R.drawable.border_box);

Original question:

I need to set my item element backgrounds with ContextCompat, but I don't know what to put to the context

This I tried:

public Context context;

@Override
public void onBindViewHolder(@NonNull GameViewHolder holder, int position) {

  holder.mTextPar.setBackground(ContextCompat.getDrawable(context, R.drawable.border_box));
}

When I open the Activity where this GameAdapter "works", the app instantly crashes and error report prefer to this line where I have this holder.mTextPar.setBackground(ContextCompat.getDrawable(context, R.drawable.border_box));

Answer 1

All answers telling you to take context as a parameter is wrong or redundant, you already have a way of getting context from your view:

@Override
public void onBindViewHolder(@NonNull GameViewHolder holder, int position) {
  Context context = holder.itemView.getContext(); 
}

Answer 2

It's unclear what adapter you are talking about, ArrayAdapter , RecyclerView adapter; please mention it; also write more codes to help others understand what/where the context is needed. Generally if it's RecyclerView Adapter, the context will of views', eg itemView.getContext() , if it's ArrayAdapter , there's a getContext() method.

Answer 3

In your adapter constructor , add context as parameter.

public Context context;

public YourAdapterClass(Context context){
    this.context = context;
}

@Override
public void onBindViewHolder(@NonNull GameViewHolder holder, int position) {
    holder.mTextPar.setBackground(ContextCompat.getDrawable(context, R.drawable.border_box));
}