去网上找了下资料，然后自己整理了下二级、三级菜单的实现，直接上代码。
Recyclerview记得要导包：implementation 'com.android.support:recyclerview-v7:28.0.0'
一、首先在app下的build.gradle中加入：
//适配器 implementation 'com.github.CymChad:BaseRecyclerViewAdapterHelper:2.6.1'
二、在project下的build.gradle中加入：
maven { url 'https://jitpack.io' }
如图：
三、建立三个bean类并实现MultiItemEntity
public class ExpandItem extends AbstractExpandableItem<Expand1Item> implements MultiItemEntity {
private String title;
public ExpandItem(String title) {
this.title = title;
}
@Override
public int getLevel() {
return 0;
}
@Override
public int getItemType() {
return QuickExpandableAdapter.TYPE_LEVEL_0;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
}
public class Expand1Item extends AbstractExpandableItem<Expand2Item> implements MultiItemEntity {
private String title;
public Expand1Item(String title){
this.title = title;
}
@Override
public int getLevel() {
return 1;
}
@Override
public int getItemType() {
return QuickExpandableAdapter.TYPE_LEVEL_1;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
}
public class Expand2Item implements MultiItemEntity {
private String title;
public Expand2Item(String title) {
this.title = title;
}
@Override
public int getItemType() {
return QuickExpandableAdapter.TYPE_LEVEL_2;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
}
四、建立QuickExpandableAdapter
public class QuickExpandableAdapter extends BaseMultiItemQuickAdapter<MultiItemEntity, BaseViewHolder> {
public static final int TYPE_LEVEL_0 = 0;
public static final int TYPE_LEVEL_1 = 1;
public static final int TYPE_LEVEL_2 = 2;
/**
* * Same as QuickAdapter#QuickAdapter(Context,int) but with
* * some initialization data.
* *
* * @param data A new list is created out of this one to avoid mutable list
*
*/
public QuickExpandableAdapter(List<MultiItemEntity> data) {
super(data);
addItemType(TYPE_LEVEL_0, R.layout.view_expand_0);
addItemType(TYPE_LEVEL_1, R.layout.view_expand_1);
addItemType(TYPE_LEVEL_2, R.layout.view_expand_2);
}
@Override
protected void convert(final BaseViewHolder helper, MultiItemEntity item) {
switch (helper.getItemViewType()) {
case TYPE_LEVEL_0:
final ExpandItem item0 = (ExpandItem) item;
helper.setText(R.id.expand_list_item0_tv, item0.getTitle());
helper.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int pos = helper.getAdapterPosition();
if (item0.isExpanded()) {
collapse(pos);
Toast.makeText(mContext, "收起：" + item0.getTitle(), Toast.LENGTH_SHORT).show();
} else {
expand(pos);
Toast.makeText(mContext, "展开：" + item0.getTitle(), Toast.LENGTH_SHORT).show();
}
}
});
break;
case TYPE_LEVEL_1:
final Expand1Item item1 = (Expand1Item) item;
helper.setText(R.id.expand_list_item1_tv, item1.getTitle());
helper.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int pos = helper.getAdapterPosition();
if (item1.isExpanded()) {
collapse(pos, false);
Toast.makeText(mContext, "收起：" + item1.getTitle(), Toast.LENGTH_SHORT).show();
} else {
expand(pos, false);
Toast.makeText(mContext, "展开：" + item1.getTitle(), Toast.LENGTH_SHORT).show();
}
}
});
break;
case TYPE_LEVEL_2:
final Expand2Item item2 = (Expand2Item) item;
helper.setText(R.id.expand_list_item2_tv, item2.getTitle());
helper.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(mContext, "点击：" + item2.getTitle(), Toast.LENGTH_SHORT).show();
}
});
break;
}
}
}
五、主界面代码
public class ListActivity extends AppCompatActivity {
private QuickExpandableAdapter expandableAdapter;
private RecyclerView recyclerView;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);
recyclerView = findViewById(R.id.recyclerView);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
//设置布局管理器
recyclerView.setLayoutManager(layoutManager);
//设置为垂直布局，这也是默认的
layoutManager.setOrientation(OrientationHelper.VERTICAL);
//设置增加或删除条目的动画
recyclerView.setItemAnimator(new DefaultItemAnimator());
expandableAdapter = new QuickExpandableAdapter(getExpandListData(10));
expandableAdapter.openLoadAnimation(BaseQuickAdapter.SLIDEIN_RIGHT);
recyclerView.setAdapter(expandableAdapter);
expandableAdapter.expandAll(0, true);
}
private List<MultiItemEntity> getExpandListData(int count) {
int lvCount = count;
int lv1Count = 3;
int lv2Count = 5;
List<MultiItemEntity> data = new ArrayList<>();
for (int i = 0; i < lvCount; i++) {
ExpandItem item0 = new ExpandItem("一级列表标题" + i);
for (int j = 0; j < lv1Count; j++) {
Expand1Item item1 = new Expand1Item("二级列表标题" + j);
for (int k = 0; k < lv2Count; k++) {
item1.addSubItem(new Expand2Item("三级列表标题" + k));
}
item0.addSubItem(item1);
}
data.add(item0);
}
return data;
}
}
六、布局文件
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_vertical"/>
</LinearLayout>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="@+id/expand_list_item0_tv"
android:layout_width="match_parent"
android:layout_height="30dp"
android:gravity="center_vertical"
android:text="一级菜单"/>
</LinearLayout>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="@+id/expand_list_item1_tv"
android:layout_width="match_parent"
android:layout_height="30dp"
android:gravity="center_vertical"
android:text="二级菜单"/>
</LinearLayout>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="@+id/expand_list_item2_tv"
android:layout_width="match_parent"
android:layout_height="30dp"
android:gravity="center_vertical"
android:text="三级菜单"/>
</LinearLayout>
好了，到这里代码已经全部写完了，因为很简单，所以就写的粗糙了些，拿上能直接用。
这里有个问题：
1.是和我做的项目有关联，如果你的recycleView外面嵌套了NestedScrollView的话，数据量一大就会导致你的列表好卡，我表示深受其害，这是因为你嵌套了NestedScrollView后，会把recyclerview所有的条目都加载出来，相当于吧recycleView的复用机制给禁掉。想想多可怕~~~
2.用ScrollView虽然可以复用，但是又会与recyclerview有滑动冲突，所以最好是不要嵌套，要不然又要解决冲突。
因为我之前解决NestedScrollView和Recyclerview的冲突就是禁掉了Recyclerview的滑动事件，只用外层NestedScrollView的滑动事件，所以最后坑了自己一把。。。。。。。。