尝试调用虚拟方法 [空对象引用]

Question

我在过去 5 天里一直在尝试解决这个问题。我真的不知道如何解决它。我得到Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference。检查我的代码：

RecyclerView.java

package etes.xdda.music;

import android.app.Dialog;

import android.content.Context;

import android.content.Intent;

import android.graphics.Color;

import android.graphics.drawable.ColorDrawable;

import android.media.MediaPlayer;

import android.support.v7.widget.RecyclerView;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.ImageButton;

import android.widget.ImageView;

import android.widget.LinearLayout;

import android.widget.TextView;

import java.util.List;

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.MyViewHolder> implements View.OnClickListener{

    Context mContext;

    List<mList> mData;

    Dialog myDialog;

    private MediaPlayer mediaPlayer;

    private int playbackPosition=0;

    private LinearLayout menu_dialog;

    public RecyclerViewAdapter(Context mContext, List<mList> mData) {

        this.mContext = mContext;

        this.mData = mData;

    }

    }

}