写在前面：
最近项目中使用一个三级展示列表，要求第一级和第二季都可以折叠，并有不同的图标变换，第三层展示数据，可点击。经过一盘折腾，算是实现了，效果就在下面：
这里写图片描述
思路：
最外层是ExpandableListView，它的子视图又是一个ExpandableListView,这个子ExpandableListView的子视图是我们的第三级展示界面，也就是GridView。分析清楚了之后，写起来就简单了，下面说说遇到的问题。
1，最外层的ExpandableListView嵌套的子ExpandableListView必须解决显示不全的问题。
2，在解决了上面的问题后，会发现，最里层的GridView如果不做处理也会出现显示不全的问题。
3，当上述两个问题都解决了之后，如果我们把最外层和第二层的ExpandableListView都使用自定义的ExpandableListView时，任然会出现子ExpandableListView显示不全问题，所以，这两个ExpandableListView不能使用同一个。
思路和问题都搞定了，我们现在看看主要的类代码：
这是MainActivity.java初始化方法代码
public class MainActivity extends AppCompatActivity {
private ExpandableListView expandableListView;
private List<String> groupList = new ArrayList<>();
private ParentExpandAdapter parentExpandAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
initData();
initView();
}
private void initData() {
for (int i = 0; i < 11; i++) {
groupList.add("Android工程师之版权 " + (1 + i));
}
}
private void initView() {
setContentView(R.layout.activity_main);
expandableListView = (ExpandableListView) findViewById(R.id.expand_main);
parentExpandAdapter = new ParentExpandAdapter(MainActivity.this, groupList);
expandableListView.setAdapter(parentExpandAdapter);
// 被展开组的监听
expandableListView.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {
@Override
public void onGroupExpand(int groupPosition) {
// 保证每次只有一个组是展开状态
for (int i = 0; i < parentExpandAdapter.getGroupCount(); i++) {
if (i != groupPosition) {
expandableListView.collapseGroup(i);
}
}
}
});
}
}
初始化了ExpandableListView，并设置了每次只展开一个组监听。
ParentExpandAdapter.java代码
public class ParentExpandAdapter extends BaseExpandableListAdapter {
private Context context;
private List<String> parentList;
public ParentExpandAdapter(Context context, List<String> parentList) {
this.context = context;
this.parentList = parentList;
}
@Override
public int getGroupCount() {
return parentList.size();
}
@Override
public int getChildrenCount(int groupPosition) {
return 5;
}
@Override
public Object getGroup(int groupPosition) {
return parentList.get(groupPosition);
}
@Override
public Object getChild(int groupPosition, int childPosition) {
return parentList.get(childPosition);
}
@Override
public long getGroupId(int groupPosition) {
return groupPosition;
}
@Override
public long getChildId(int groupPosition, int childPosition) {
return childPosition;
}
@Override
public boolean hasStableIds() {
return false;
}
@Override
public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
ParentViewHolder parentHolder;
if (null == convertView) {
parentHolder = new ParentViewHolder();
convertView = View.inflate(context, R.layout.fire_tab_parent_group_item, null);
parentHolder.parentTv = (TextView) convertView.findViewById(R.id.parentGroupTV);
parentHolder.parentIv = (ImageView) convertView.findViewById(R.id.iv_parent_group_indicator);
convertView.setTag(parentHolder);
} else {
parentHolder = (ParentViewHolder) convertView.getTag();
}
parentHolder.parentTv.setText(parentList.get(groupPosition));
if (isExpanded) {
parentHolder.parentIv.setImageResource(R.drawable.icon_arrow_up);
} else {
parentHolder.parentIv.setImageResource(R.drawable.icon_arrow_down);
}
return convertView;
}
@Override
public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
ChildViewHolder childHolder;
if (null == convertView) {
childHolder = new ChildViewHolder();
convertView = View.inflate(context, R.layout.item_expand_group_child, null);
childHolder.childExpandLv = (ExpandableListView) convertView.findViewById(R.id.expand_group_item);
convertView.setTag(childHolder);
} else {
childHolder = (ChildViewHolder) convertView.getTag();
}
childHolder.childExpandLv.setAdapter(new ChildExpandAdapter(context, parentList.subList(3, 7)));
return convertView;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return true;
}
class ParentViewHolder {
TextView parentTv;
ImageView parentIv;
}
class ChildViewHolder {
// 二级视图又是一个ExpandableListView
ExpandableListView childExpandLv;
}
}
因为一级只有一个TextView和一个ImageView，比较简单。因为子视图又是一个ExpandableListView，所以这里设置了监听，保证每次只展开一个分组，如果没有这个需求当然可以不设置，另外就是通过判断增加了指示箭头。
二级适配器ChildExpandAdapter.java代码
public class ChildExpandAdapter extends BaseExpandableListAdapter {
private Context context;
private List<String> parentList;
public ChildExpandAdapter(Context context, List<String> parentList) {
this.context = context;
this.parentList = parentList;
}
@Override
public int getGroupCount() {
return parentList.size();
}
@Override
public int getChildrenCount(int groupPosition) {
return 1;
}
@Override
public Object getGroup(int groupPosition) {
return parentList.get(groupPosition);
}
@Override
public Object getChild(int groupPosition, int childPosition) {
return parentList.get(childPosition);
}
@Override
public long getGroupId(int groupPosition) {
return groupPosition;
}
@Override
public long getChildId(int groupPosition, int childPosition) {
return childPosition;
}
@Override
public boolean hasStableIds() {
return false;
}
@Override
public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
ParentViewHolder parentHolder;
if (null == convertView) {
parentHolder = new ParentViewHolder();
convertView = View.inflate(context, R.layout.fire_tab_child_group_item, null);
parentHolder.parentTv = (TextView) convertView.findViewById(R.id.childGroupTV);
parentHolder.parentIv = (ImageView) convertView.findViewById(R.id.iv_fire_tab_child_indicator);
convertView.setTag(parentHolder);
} else {
parentHolder = (ParentViewHolder) convertView.getTag();
}
parentHolder.parentTv.setText(parentList.get(groupPosition));
if (isExpanded) {
parentHolder.parentIv.setImageResource(R.drawable.icon_arrow_up);
} else {
parentHolder.parentIv.setImageResource(R.drawable.icon_arrow_down);
}
return convertView;
}
@Override
public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
ChildViewHolder childHolder;
if (null == convertView) {
childHolder = new ChildViewHolder();
convertView = View.inflate(context, R.layout.item_child_child, null);
childHolder.gridView = (GridView) convertView.findViewById(R.id.gv_child_child_item);
convertView.setTag(childHolder);
} else {
childHolder = (ChildViewHolder) convertView.getTag();
}
childHolder.gridView.setAdapter(new GridViewAdapter(context, getList()));
return convertView;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return true;
}
class ParentViewHolder {
TextView parentTv;
ImageView parentIv;
}
class ChildViewHolder {
// 此ExpandableListView的ClildView又是一个GridView
GridView gridView;
}
private List<String> getList() {
List<String> list = new ArrayList<>();
for (int i = 0; i < 50; i++) {
list.add("android " + i);
}
return list;
}
}
根据我们前面的分析，这里的二级ChildView是一个GridView，这里做了初始化，并设置了点击监听。
再来看看最重要的代码——自定义ExpandableListView
public class CustomExpandableListview extends ExpandableListView {
public CustomExpandableListview(Context context) {
super(context);
}
public CustomExpandableListview(Context context, AttributeSet attrs) {
super(context, attrs);
}
public CustomExpandableListview(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int expandSpec = MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE >> 2,
MeasureSpec.AT_MOST);
super.onMeasure(widthMeasureSpec, expandSpec);
}
}
这里通过测量，计算出子ExpandableListView的高度，解决了显示不全问题，GridView也是一样的。
至此，除了GridView的适配器代码外，其它的都贴出来了，完整代码已上传至github，关注公众号“code小生”获取地址以及更多项目地址。
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