Android create comment layout merge ViewStub layout programical

in my application i have section as view comment like with GooglyPlay. this comments count is unknow and i must be add layout from external layout into current layout, i get data from json and i want to create this section with json count. for example i like to have :

my json array is:

[
    {"comment":"test1"},
    {"comment":"test2"},
    {"comment":"test3"},
    {"comment":"test4"}
]

now in this code i must be add external layout and add it into current layout:

<ViewStub
    android:id="@+id/layout_stub_comments"
    android:inflatedId="@+id/comments_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

attach layout from code and retrive data from json:

private void parseCommentsContent(String jsonStr) {
        try {
            JSONArray jsonArray = new JSONArray(jsonStr);
            for (int i = 0; i < jsonArray.length(); i++) {
                String comment = jsonArray.getJSONObject(i).getString(SV.FIELD_COMMENT);
                ViewStub stub = (ViewStub) findViewById(R.id.layout_stub_comments);
                stub.setLayoutResource(R.layout.layout_comments);
                View inflated = stub.inflate();

                TextView comment_text = (TextView) inflated.findViewById(R.id.tv_comment_text);
                comment_text.setText(comment);
            }

        } catch (JSONException e) {
            e.printStackTrace();
            UC.debugLog(traceElements, G.DEBUG, SV.Messages[3]);
        }
    }

in this phase i get NullPointerException for this line:

stub.setLayoutResource(R.layout.layout_comments);

layout_comments layout designed into layout folder as:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://ift.tt/nIICcg"
              android:orientation="horizontal"
              android:layout_width="fill_parent"
              android:layout_height="wrap_content" android:layout_marginTop="50dp">
    <LinearLayout
            android:orientation="vertical"
            android:layout_width="0dp"
            android:layout_height="fill_parent" android:layout_weight="1">
        <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="New Text"
                android:id="@+id/tv_comment_text"/>
    </LinearLayout>
</LinearLayout>

why i get i get NullPointerException? thanks