Android ExpandableListView的使用技巧

Android ExpandableListView的使用技巧

转载请注明 作者：田野光 地址：http://blog.csdn.net/lovefish2/article/details/45920917

ExpandableListView是listview的官方扩展组件, 垂直方向上item分为两层, group item和child item,点击group item可以展开和折叠child item.基础的使用方法也非常简单. 与之对应的是BaseExpandableListAdapter. 这是只说一下一些常用需求的方法.

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指定 默认展开的item

ExpandableListView vListView = (ExpandableListView) findViewById(R  .id.***);vListView.expandGroup(0); //默认展开第一项

隐藏分割线

android:childDivider="@null"android:childIndicator="@null"android:divider="@null"android:groupIndicator="@null"

限制最多只展开一项child item

vListView.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {            int previousGroup = 0;  //最初展开的item,若未指定,可设为-1            @Override            public void onGroupExpand(int groupPosition) {                if (groupPosition != previousGroup)                    vListView.collapseGroup(previousGroup);                previousGroup = groupPosition;            }        });

与SwipeRefreshLayout搭配使用下拉刷新

我们知道, SwipeRefreshLayout 会监听滑动操作,并相应触发下拉刷新,如果布局文件中内含了可滑动的控件,如ScrollView等,则很有可能会在错误的时候触发下拉刷新(譬如当你下拉页面想要浏览上方内容), 好消息是所有AbsListView 子类,包括listview, ExpandableListView 等控件,只要是XML布局内部的直接下级,SwipeRefreshLayout都内置了判断方法,可以避免错误的触发.不过其他情况就需要单独处理了.

<SwipeRefreshLayout        android:layout_width="match_parent"        android:layout_height="match_parent">      <ExpandableListView            android:layout_width="match_parent"            android:layout_height="match_parent" /></SwipeRefreshLayout>

• 非直接下级的AbsListView
  参考(http://stackoverflow.com/questions/23341735/swiperefreshlayout-swipe-down-to-refresh-but-not-move-the-view-pull-down)

<SwipeRefreshLayout        android:layout_width="match_parent"        android:layout_height="match_parent">    <LinearLayout        android:layout_width="match_parent"        android:layout_height="match_parent" />          <ExpandableListView                android:layout_width="match_parent"                android:layout_height="match_parent" />    </LinearLayout></SwipeRefreshLayout>

解决办法:

listView.setOnScrollListener(new OnScrollListener() {@Overridepublic void onScrollStateChanged(AbsListView view, int scrollState) {}@Overridepublic void onScroll(AbsListView view, int firstVisibleItem,        int visibleItemCount, int totalItemCount) {    boolean enable = false;    if(listView != null && listView.getChildCount() > 0){        boolean firstItemVisible = listView.getFirstVisiblePosition() == 0;        boolean topOfFirstItemVisible = listView.getChildAt(0).getTop() == 0;        enable = firstItemVisible && topOfFirstItemVisible;    }    swipeRefreshLayout.setEnabled(enable);}});

• 和RecyclerView

  可以参考我的这篇博客: Android开发 解决RecyclerView in SwipeRefreshLayout触发下拉刷新的bug

增加item扩展和折叠的动画

ExpandableListView默认折叠和展开item简单粗暴,通常情况下我们想要平滑一点,轻柔一点(别想歪了-_-), 我们看到API里,官方有提供动画的方案

public boolean expandGroup (int groupPos, boolean animate)

但缺点是动画很粗糙,可以参见源码的处理:

AnimatedExpandableListView vListView = (AnimatedExpandableListView) findViewById(R  .id.***);public boolean expandGroup(int groupPos, boolean animate) {        ExpandableListPosition elGroupPos = ExpandableListPosition.obtain(                ExpandableListPosition.GROUP, groupPos, -1, -1);        PositionMetadata pm = mConnector.getFlattenedPos(elGroupPos);        elGroupPos.recycle();        boolean retValue = mConnector.expandGroup(pm);        if (mOnGroupExpandListener != null) {            mOnGroupExpandListener.onGroupExpand(groupPos);        }        if (animate) {            final int groupFlatPos = pm.position.flatListPos;            final int shiftedGroupPosition = groupFlatPos + getHeaderViewsCount();            //动画仅仅是这样            smoothScrollToPosition(shiftedGroupPosition + mAdapter.getChildrenCount(groupPos),                    shiftedGroupPosition);        }        pm.recycle();        return retValue;    }

而且API要求大于14.所以通常我们都是采用其他方式,这里我推荐AnimatedExpandableListView,一个第三方写的ExpandableListView类, 用法很简单,继承AnimatedExpandableListAdapter类,手动调用Animation方法

listView.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {            @Override            public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {                if (vBusInfo.isGroupExpanded(groupPosition)) {                    vBusInfo.collapseGroupWithAnimation(groupPosition);                } else {                    vBusInfo.expandGroupWithAnimation(groupPosition);                }                return true;            }        });

好啦,关于ExpandableListView的介绍就先到这啦,欢迎大家提出批评建议,谢谢大家~

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