You must call removeView() on the child's parent first

et1 = (EditText)findViewById(R.id.editText1);
builder.setView(et1);  -- AlertDialog.Builder builder

et1 = new EditText(this);
builder.setView(et1);

LayoutInflater inflater = LayoutInflater.from(this);  
            View textEntryView = inflater.inflate(R.layout.test1, null);  
            et1 = (EditText)textEntryView.findViewById(R.id.editText1);
builder.setView(textEntryView ); 注意这里是textEntryView ，不是et1