android: how to add children from an xml layout in

问题:

In my xml layouts I have a custom view in which i will put some children like:

<com.proj.layouts.components.ScrollLayout
    android:id="@+id/slBody"
    android:layout_width="700dp"
    android:layout_height="400dp">
<TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="child1"/>
<TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="child2"/>
<TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="child3"/>
<TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="child4"/>
<TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="child5"/>
</com.proj.layouts.components.ScrollLayout>

Let me explain a bit more. I wrote a custom ScrollView in which I already have a container defined, for the children. So I just want to put them there.

public class ScrollLayout extends LinearLayout {
    // View responsible for the scrolling
    private FrameLayout svContainer;
    // View holding all of the children
    private LinearLayout llContainer;

    public ScrollLayout(Context context) {
        super(context);
        init();
    }

    public ScrollLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        super.removeAllViews(); // kill old containers


        svContainer = new HorizontalScroll(getContext());
        llContainer = new LinearLayout(getContext());
        llContainer.setOrientation(orientation);
        svContainer.addView(llContainer);

        svContainer.setLayoutParams(new FrameLayout.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
        llContainer.setLayoutParams(new FrameLayout.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));

        addView(svContainer);


    }

    ... I left out the part which takes care of the scroll event ...
}

What is the way to add Child* to llContainer?

回答1:

Why don't you just add all the children to the LinearLayout from your ScrollLayout? This should be done in the onFinishInflate() method.

for (int i = 0; i<getChildCount(); i++)
{
    View v = getChildAt(i);
    removeViewAt(i);
    llContainer.addView(v);
}

When you write your structure in the XML file - all inner views are children of your custom layout. Just replace it to LinearLayout.

回答2:

Jin35's answer has a serious problem: getChildCount() changes value over the iterations because we are removing the children.

This should be a better solution:

while (getChildCount() > 0) {
    View v = getChildAt(0);
    removeViewAt(0);
    llContainer.addView(v);
}

回答3:

I agree Jin35's answer is flawed. Also, the svContainer is added, so we cannot continue until getChildCount() == 0.

By the end of init(), getChildCount() == 1, since svContainer has been added but the TextViews have not. By the end of onFinishInflate(), the TextViews have been added and should be at positions 1, 2, 3, 4 and 5. But if you then remove the View at position 1, the indices of the others will all decrease by 1 (standard List behaviour).

I would suggest:

@Override
protected void onFinishInflate() {
    super.onFinishInflate();

    View v;
    while ((v = getChildAt(1)) != null) {
        removeView(v);
        llContainer.addView(v);
    }
}