以编程方式在RelativeLayout中堆叠子视图

Question

In my app I'm trying to mimic an SMS messaging application's conversation view where sent messages align to the left margin, and received messages align to the right. I'm using a custom RelativeLayout to achieve the left/right alignment, and I'm adding the TextView s dynamically at runtime, by calling a method on my custom RelativeLayout .

The problem I'm having is that as I'm adding the TextView s that follow the first one, they are being placed one on top of the other (at the same x,y) instead of being stacked vertically (increasing y).

Here's my code that adds the TextView :

TextView txt = new TextView(mContext);
RelativeLayout.LayoutParams params =
    new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT,
                                    LayoutParams.WRAP_CONTENT);
params.addRule(sent ? ALIGN_PARENT_LEFT : ALIGN_PARENT_RIGHT);  

// make sure this message is positioned below the last one
if (getChildCount() > 0) {
    params.addRule(BELOW, getChildAt(getChildCount() - 1).getId());
}

txt.setLayoutParams(params);
txt.setText(msg);

addView(txt);

My custom RelativeView is defined thusly:

<com.foo.bar.ConversationLayout
        android:id="@+id/loConvo"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>

Any help is appreciated.

Thanks!

Answer 1

From what I can see is that you are not setting any IDs for the TextViews you are adding. So, when you call:

params.addRule(BELOW, getChildAt(getChildCount() - 1).getId());

getId() returns NO_ID .

From documentation on View class: getId() returns a positive integer used to identify the view or NO_ID if the view has no ID .

NO_ID is used to mark a View that has no ID .

Try setting IDs to your TextViews using either setId(yourGivenId) or setId(View.generateViewId()) and see if that helps solve the problem.