尝试调用虚方法 'void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager

Question

I am trying to implement RecyclerView in one of my custom alert dialogue. Its crashing with error called

Attempt to invoke virtual method 'void android.support.v7.widget.RecyclerView.setLayoutManager(android.support.v7.widget.RecyclerView$LayoutManager)' on a null object reference 

on this line

hsv_font_bartextview.setLayoutManager(layoutManager);

My function code of custom dialogue is like below

private void showGotoPageDialog() {

        final Dialog mDialog = new Dialog(SettingsActivity.this);
        mDialog.setContentView(R.layout.font_dialogue);
        mDialog.getWindow().setLayout(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
        LinearLayoutManager layoutManager
                = new LinearLayoutManager(SettingsActivity.this, LinearLayoutManager.HORIZONTAL, false);
        hsv_font_bartextview=(RecyclerView)findViewById(R.id.hsv_font_bartextview);
        hsv_font_bartextview.setLayoutManager(layoutManager);


        TextAdapterTextview textAdaptertextview = new TextAdapterTextview(SettingsActivity.this, Globle.getFontArray());
        hsv_font_bartextview.setAdapter(textAdaptertextview);
        textAdaptertextview.setOnClickLIstner(new OnTClickLIstner() {
            @Override
            public void onClick(View v, String image, int position) {
                Toast.makeText(SettingsActivity.this,image,Toast.LENGTH_SHORT).show();

            }
        });

        mDialog.show();
        TextView dismiss = (TextView) mDialog.findViewById(R.id.dialog_dismiss);
        dismiss.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mDialog.dismiss();
            }
        });
    }

Let me know if someone can help me for solve my issue. Thanks

Answer 1

hsv_font_bartextview=(RecyclerView)findViewById(R.id.hsv_font_bartextview);

findViewById() returns null , because your activity does not have a widget with that ID. Your dialog might, but the dialog is not the activity. Call findViewById() on the dialog if that is where the hsv_font_bartextview is.