sample
效果图
ExpandableList可扩展的下拉列表，可扩展性在于点击父item可以拉下或收起子列表
Adapter继承自BaseExpandableListAdapter,如下图所示，会实现一大堆方法
public class SimpleExpandableListAdapter extends BaseExpandableListAdapter {
@Override
public int getGroupCount() {
return 0;
}
@Override
public int getChildrenCount(int groupPosition) {
return 0;
}
@Override
public Object getGroup(int groupPosition) {
return null;
}
@Override
public Object getChild(int groupPosition, int childPosition) {
return null;
}
@Override
public long getGroupId(int groupPosition) {
return 0;
}
@Override
public long getChildId(int groupPosition, int childPosition) {
return 0;
}
@Override
public boolean hasStableIds() {
return false;
}
@Override
public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
return null;
}
@Override
public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
return null;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return false;
}
}
这个时候肯定会选择封装一个SimpleBaseAdapter,封装好了之后可以极大的减少往后的代码量
public abstract class SimpleBaseExpandableListAdapter extends BaseExpandableListAdapter {
protected List expandableListTitle;
private HashMap> expandableListDetail;
public SimpleBaseExpandableListAdapter(List expandableListTitle, HashMap> expandableListDetail) {
if (expandableListTitle != null && expandableListDetail != null) {
this.expandableListDetail = expandableListDetail;
this.expandableListTitle = expandableListTitle;
}
}
@Override
public int getGroupCount() {
return expandableListTitle.size();
}
@Override
public int getChildrenCount(int groupPosition) {
return expandableListDetail.get(expandableListTitle.get(groupPosition)).size();
}
@Override
public Object getGroup(int groupPosition) {
return this.expandableListTitle.get(groupPosition);
}
@Override
public Object getChild(int groupPosition, int childPosition) {
return this.expandableListDetail.get(this.expandableListTitle.get(groupPosition)).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) {
return getGroup(groupPosition, isExpanded, convertView, parent);
}
@Override
public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
return getChild(groupPosition, childPosition, isLastChild, convertView, parent);
}
abstract View getGroup(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent);
abstract View getChild(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent);
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return true;
}
}
继承自封装好的Adapter，可以看到我们只要关心组view和子view就行了，由于这里只是简单的测试，并没有用ViewHolder去实现复用缓存
public class SimpleAdapter extends SimpleBaseExpandableListAdapter {
public SimpleAdapter(List expandableListTitle, HashMap> expandableListDetail) {
super(expandableListTitle, expandableListDetail);
}
@Override
View getGroup(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
String data = expandableListTitle.get(groupPosition);
convertView = View.inflate(parent.getContext(), R.layout.group_item, null);
TextView textView = (TextView) convertView.findViewById(R.id.tv_group);
ImageView imageView = (ImageView) convertView.findViewById(R.id.iv);
textView.setText(data);
if (isExpanded) {
imageView.setImageResource(R.drawable.dropdown);
} else {
imageView.setImageResource(R.drawable.select);
}
return convertView;
}
@Override
View getChild(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
String data = (String) this.getChild(groupPosition, childPosition);
convertView = View.inflate(parent.getContext(), R.layout.child_item, null);
TextView tv = (TextView) convertView.findViewById(R.id.tv_child);
tv.setText(data);
return convertView;
}
}
测试数据实现类：
public class ExpandableListDataPump {
public static LinkedHashMap> getData() {
LinkedHashMap> expandableListDetail = new LinkedHashMap<>();
List technology = new ArrayList<>();
technology.add("A");
technology.add("B");
technology.add("C");
technology.add("D");
technology.add("E");
technology.add("F");
technology.add("G");
technology.add("H");
technology.add("I");
technology.add("J");
List entertainment = new ArrayList<>();
entertainment.add("A");
entertainment.add("B");
entertainment.add("C");
entertainment.add("D");
entertainment.add("E");
entertainment.add("F");
entertainment.add("G");
entertainment.add("H");
entertainment.add("I");
entertainment.add("J");
List science = new ArrayList<>();
science.add("A");
science.add("B");
science.add("C");
science.add("D");
science.add("E");
science.add("F");
science.add("G");
science.add("H");
science.add("I");
science.add("J");
expandableListDetail.put("SIMPLE ONE", technology);
expandableListDetail.put("SIMPLE TWO", entertainment);
expandableListDetail.put("SIMPLE THREE", science);
return expandableListDetail;
}
}
