how to display footer view to the end of the scree

问题:

I want to add a footer to the listview. When the number of list items are more,the footer works fine. But when listview has very few items,the footer gets displayed in the middle of the screen,just below the listview .which looks shabby.In such case i want the footer to align parent bottom. Thankyou in anticipation.

回答1:

it is a simplest example of what you want. you can customize it:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/RelativeLayout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

   <ListView
        android:id="@+id/listView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@+id/footer"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" >

    </ListView>


    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="90dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:id="@+id/footer" >

    </RelativeLayout>


</RelativeLayout>

if you want do that you said in comment you must set layout param's of footer in code, you must get the size of your list, then get the number of row that shows in screen, then

 if (listSize < numRow)
     //set footer to bottom of your list
 else
     //  android:layout_alignParentBottom="true"

回答2:

Maybe your listview's height is set to wrap_content?

As far as I know the footer is added at the bottom of the listview. If you set the listview's height to match_parent it should be aligned to the bottom and also the footer should be displayed there. (If you use a relative layout simply set listview's attribute alignParentBottom="true" in your .xml file)

回答3:

You can use RecyclerView with RecyclerView.ItemDecoration to implement this behavior.

public class StickyFooterItemDecoration extends RecyclerView.ItemDecoration {

/**
 * Top offset to completely hide footer from the screen and therefore avoid noticeable blink during changing position of the footer.
 */
private static final int OFF_SCREEN_OFFSET = 5000;

@Override
public void getItemOffsets(Rect outRect, final View view, final RecyclerView parent, RecyclerView.State state) {
    int adapterItemCount = parent.getAdapter().getItemCount();
    if (isFooter(parent, view, adapterItemCount)) {
        //For the first time, each view doesn't contain any parameters related to its size,
        //hence we can't calculate the appropriate offset.
        //In this case, set a big top offset and notify adapter to update footer one more time.
        //Also, we shouldn't do it if footer became visible after scrolling.
        if (view.getHeight() == 0 && state.didStructureChange()) {
            hideFooterAndUpdate(outRect, view, parent);
        } else {
            outRect.set(0, calculateTopOffset(parent, view, adapterItemCount), 0, 0);
        }
    }
}

private void hideFooterAndUpdate(Rect outRect, final View footerView, final RecyclerView parent) {
    outRect.set(0, OFF_SCREEN_OFFSET, 0, 0);
    footerView.post(new Runnable() {
        @Override
        public void run() {
            parent.getAdapter().notifyDataSetChanged();
        }
    });
}

private int calculateTopOffset(RecyclerView parent, View footerView, int itemCount) {
    int topOffset = parent.getHeight() - visibleChildsHeightWithFooter(parent, footerView, itemCount);
    return topOffset < 0 ? 0 : topOffset;
}

private int visibleChildsHeightWithFooter(RecyclerView parent, View footerView, int itemCount) {
    int totalHeight = 0;
    //In the case of dynamic content when adding or removing are possible itemCount from the adapter is reliable,
    //but when the screen can fit fewer items than in adapter, getChildCount() from RecyclerView should be used.
    int onScreenItemCount = Math.min(parent.getChildCount(), itemCount);
    for (int i = 0; i < onScreenItemCount - 1; i++) {
        totalHeight += parent.getChildAt(i).getHeight();
    }
    return totalHeight + footerView.getHeight();
}

private boolean isFooter(RecyclerView parent, View view, int itemCount) {
    return parent.getChildAdapterPosition(view) == itemCount - 1;
}

}

Make sure to set match_parent for the RecyclerView height.

Please have a look at the sample application https://github.com/JohnKuper/recyclerview-sticky-footer and how it works http://sendvid.com/nbpj0806

A Huge drawback of this solution is it works correctly only after notifyDataSetChanged() throughout an application(not inside decoration). With more specific notifications it won't work properly and to support them, it requires a way more logic. Also, you can get insights from the library recyclerview-stickyheaders by eowise and improve this solution.