这是我的 EndLessScrollListener.java。有没有人遇到过这个问题，你向上滚动并且它一直滚动到列表的顶部。我正在构建一个类似于用于聊天消息的环聊的应用程序，其中最新消息就在底部。因此，要查看较旧的聊天消息，用户向上滚动并继续向右滚动到顶部。请帮忙。仅供参考，我在我的 listView 中使用这两个属性： android:stackFromBottom="true" android:transcriptMode="normal"
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
/*
* https://github.com/thecodepath/android_guides/wiki/Endless-Scrolling-with-AdapterViews
*/
public abstract class EndlessScrollListener implements OnScrollListener {
// The minimum amount of items to have below your current scroll position
// before loading more.
private int visibleThreshold = 5;
// The current offset index of data you have loaded
private int currentPage = 0;
// The total number of items in the dataset after the last load
private int previousTotalItemCount = 0;
// True if we are still waiting for the last set of data to load.
private boolean loading = true;
// Sets the starting page index
private int startingPageIndex = 0;
private boolean reverse = false;
public EndlessScrollListener() {
}
public EndlessScrollListener(int visibleThreshold) {
this.visibleThreshold = visibleThreshold;
}
public EndlessScrollListener(int visibleThreshold, boolean reverse) {
this.visibleThreshold = visibleThreshold;
this.reverse = reverse;
}
public EndlessScrollListener(int visibleThreshold, int startPage) {
this.visibleThreshold = visibleThreshold;
this.startingPageIndex = startPage;
this.currentPage = startPage;
}
// This happens many times a second during a scroll, so be wary of the code you place here.
// We are given a few useful parameters to help us work out if we need to load some more data,
// but first we check if we are waiting for the previous load to finish.
@Override
public void onScroll(AbsListView view,int firstVisibleItem,int visibleItemCount,int totalItemCount) {
// If the total item count is zero and the previous isn't, assume the
// list is invalidated and should be reset back to initial state
if (totalItemCount < previousTotalItemCount) {
this.currentPage = this.startingPageIndex;
this.previousTotalItemCount = totalItemCount;
if (totalItemCount == 0) { this.loading = true; }
}
// If it's still loading, we check to see if the dataset count has
// changed, if so we conclude it has finished loading and update the current page
// number and total item count.
if (loading && (totalItemCount > previousTotalItemCount)) {
loading = false;
previousTotalItemCount = totalItemCount;
currentPage++;
}
// If reverse then the firstVisibleItem is calculated wrong
if (reverse) {
firstVisibleItem = totalItemCount - firstVisibleItem;
}
// If it isn't currently loading, we check to see if we have breached
// the visibleThreshold and need to reload more data.
// If we do need to reload some more data, we execute onLoadMore to fetch the data.
if (!loading && (totalItemCount - visibleItemCount)<=(firstVisibleItem + visibleThreshold)) {
onLoadMore(currentPage + 1, totalItemCount);
loading = true;
}
}
// Defines the process for actually loading more data based on page
public abstract void onLoadMore(int page, int totalItemsCount);
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
// Don't take any action on changed
}
public void reset() {
currentPage = 0;
previousTotalItemCount = 0;
loading = true;
startingPageIndex = 0;
}
}
This is my xml file.
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/background"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<RelativeLayout
android:id="@+id/sendMessageLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:minHeight="48dp" >
<com.android.volley.toolbox.NetworkImageView
android:id="@+id/image"
android:layout_width="30dp"
android:layout_height="30dp"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:layout_marginLeft="8dp" />
<ImageView
android:id="@+id/sendMessage"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:layout_marginRight="4dp"
android:background="?android:attr/selectableItemBackground"
android:padding="8dp"
android:src="@drawable/convo_send" />
<EditText
android:id="@+id/message"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:layout_marginLeft="48dp"
android:layout_toLeftOf="@+id/sendMessage"
android:background="@android:color/transparent"
android:hint="New message"
android:inputType="textMultiLine|textCapSentences"
android:textColor="@android:color/black"
android:textColorHint="@color/g3"
android:textSize="@dimen/sp_17" />
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:layout_alignParentTop="true"
android:background="#DBDCDC" />
</RelativeLayout>
<ListView
android:id="@+id/conversation"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="@+id/sendMessageLayout"
android:cacheColorHint="@android:color/transparent"
android:choiceMode="multipleChoice"
android:descendantFocusability="afterDescendants"
android:divider="@android:color/transparent"
android:dividerHeight="3dp"
android:paddingBottom="6dp"
android:scrollbars="none"
android:stackFromBottom="true"
android:transcriptMode="normal"
tools:listitem="@layout/conversation_text" />
</RelativeLayout>