android alert 动态,android – 动态设置自定义AlertDialog内容

我有一个自定义对话框,我将其设置为一个函数：

public void customDialog(Bitmap bm,String title){

TextView dialogtext = (TextView)findViewById(R.id.layout_root);

//For above also tried r.id.popup which is the containing file for the layout

ImageView dialogimage = (ImageView)findViewById(R.id.popupimage);

dialogtext.setText(title);

dialogimage.setImageBitmap(bm);

LayoutInflater inflater = getLayoutInflater();

View layout = inflater.inflate(R.layout.popup,(ViewGroup) findViewById(R.id.layout_root));

AlertDialog.Builder builder = new AlertDialog.Builder(this);

builder.setView(layout);

builder.show();

}

每当我尝试使用Null指针异常动态设置XML字段时,对话框都会失败.我很难过,有什么想法吗？我是否必须在清单中添加一些自定义对话框？