MainActivity.java

        MaterialDialog mDialog = new MaterialDialog.Builder(this)
                .setTitle("Delete?")
                .setMessage("Are you sure want to delete this file?")
                .setCancelable(false)
                .setPositiveButton("Delete", R.drawable.ic_delete, new MaterialDialog.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int which) {
                        // Delete Operation
                    }
                })
                .setNegativeButton("Cancel", R.drawable.ic_close, new MaterialDialog.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int which) {
                        dialogInterface.dismiss();
                    }
                })
                .build();

        // Show Dialog
        mDialog.show();