我正在寻找ExpandableListView自动滚动到特定位置

编程问答 2022-08-13

问题描述

当用户从RecyclerView中选择特定的组名称时，我希望我的应用自动滚动到ExpandableList中的specificGroup。我正在使用界面来处理RecyclerView的点击

这是我的mainActivity代码：

 @Override
public void onItemClick(int position) {
    menuListForRestaurant.setVisibility(View.GONE);
    if (!menuOpenChecker){
        menuOpenChecker=true;
    }else{
        menuOpenChecker=false;
    }
    //The above code gets execute except for the below one
   listView.smoothScrollToPosition(position);// this line is not executing
}

@SuppressLint("ClickableViewAccessibility")
private void ListViewAdapter(final HashMap<String,ArrayList<ProductList>> objectMap,final ArrayList<String> headerList) {

    listViewAdapter= new RestaurantItemListView(RestaurantDetail.this.getApplicationContext(),objectMap,headerList);
    listView.setAdapter(listViewAdapter);
    listViewAdapter.notifyDataSetChanged();
}

private void RecyclerMenuView(ArrayList<String> headerList){
    menuItemRecyclerView.setLayoutManager(new linearlayoutmanager(this));
    menuItemRecyclerView.getRecycledViewPool().clear();
    menuAdapterRecyclerView= new RestaurantMenuRecyclerView(headerList,this.getApplicationContext());
    menuItemRecyclerView.setItemAnimator(new DefaultItemAnimator());
    menuItemRecyclerView.setAdapter(menuAdapterRecyclerView);
    menuAdapterRecyclerView.notifyDataSetChanged();
    menuAdapterRecyclerView.setonClick(RestaurantDetail.this);

}

就像我提到的那行不起作用，因为它在ExpandableListView中没有得到更新

在此先感谢您，谢谢任何人？

解决方法

在使用 NonScrollExpandableListView 时，ExpandableListView不会滚动。在这里，我展示了3种可能的解决方案：

  1. NonScrollExpandableListView和ScrollView（当前方法）：您不必滚动ExpandableListView，而必须滚动ScrollView。如果ExpandableListView中有任何组，则很难计算滚动位置。因此，折叠所有组然后仅扩展所需的组要容易得多。代码是这样的（我还没有测试过）：

     for (int i = 0; i < listViewAdapter.getGroupCount(); i++) listView.collapseGroup(i);
 int a = header.getHeight(); // header refers to all views above the ExpandableListView.
 a += (listViewAdapter.getGroupView(0,false,null,null).getHeight() + listView.getDividerHeight())*
         position;
 scrollView.smoothScrollTo(0,a);
 listView.expandGroup(position);

2。带有标头（NoScrollView）的ExpandableListView：启动一个新项目并尝试该示例，验证其是否符合您的要求。在这里，我使用Spinner而不是RecyclerView。

MainActivity.java：

public class MainActivity extends AppCompatActivity {

LinkedHashMap<String,ArrayList<String>> dataList;
ExpandableListView expandableListView;
CustomBaseExpandableListAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    dataList = createSampleList();
    expandableListView = findViewById(R.id.expandable_list_view);
    adapter = new CustomBaseExpandableListAdapter(getApplicationContext(),dataList);
    expandableListView.setAdapter(adapter);

    View header = getLayoutInflater().inflate(R.layout.header,null);
    Button btExpand = header.findViewById(R.id.bt_expand);
    btExpand.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            for (int i = 0; i < adapter.getGroupCount(); i++) expandableListView.expandGroup(i);
        }
    });

    Spinner spinner = findViewById(R.id.selector);
    ArrayAdapter<String> arrayAdapter = new ArrayAdapter<>(getApplication(),android.R.layout.simple_list_item_1,new ArrayList<>(dataList.keySet()));
    spinner.setAdapter(arrayAdapter);
    spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapterView,View view,int i,long l) {
            int a = 1; // Without header a=0,with header a=1.
            for (int j = 0; j < i; j++) {
                a += (expandableListView.isGroupExpanded(j) ? adapter.getChildrenCount(j) : 0) + 1;
            }
            // expandableListView.smoothScrollToPosition(a);
            expandableListView.smoothScrollToPositionFromTop(a,0);
        }
        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {
        }
    });
    expandableListView.addHeaderView(header);
}

private LinkedHashMap<String,ArrayList<String>> createSampleList() {
    LinkedHashMap<String,ArrayList<String>> dataList = new LinkedHashMap<>();
    for (int i = 0; i < 10; i++) {
        ArrayList<String> childList = new ArrayList<>();
        for (int j = 0; j < 17; j++) {
            childList.add("Item " + i + "-" + j);
        }
        dataList.put("Group " + i,childList);
    }
    return dataList;
}
}

CustomBaseExpandableListAdapter.java：

public class CustomBaseExpandableListAdapter extends BaseExpandableListAdapter {
ArrayList<String> groupList;
LinkedHashMap<String,ArrayList<String>> dataList;
Context context;

public CustomBaseExpandableListAdapter(Context context,LinkedHashMap<String,ArrayList<String>> dataList) {
    this.context = context;
    this.dataList = dataList;
    groupList = new ArrayList(dataList.keySet());
}

@Override
public int getGroupCount() {
    return groupList.size();
}

@Override
public int getChildrenCount(int i) {
    return dataList.get(groupList.get(i)).size();
}

@Override
public String getGroup(int i) {
    return groupList.get(i);
}

@Override
public String getChild(int i,int i1) {
    return dataList.get(groupList.get(i)).get(i1);
}

@Override
public long getGroupId(int i) {
    return 0;
}

@Override
public long getChildId(int i,int i1) {
    return 0;
}

@Override
public boolean hasStableIds() {
    return false;
}

@Override
public View getGroupView(int i,boolean b,ViewGroup viewGroup) {
    TextView textView;
    if (view == null) {
        textView = new TextView((context));
        textView.setTextSize(30);
        textView.setPadding(80,0);
    } else {
        textView = (TextView) view;
    }
    textView.setText(getGroup(i));
    return textView;
}

@Override
public View getChildView(int i,int i1,ViewGroup viewGroup) {
    TextView textView;
    if (view == null) {
        textView = new TextView((context));
        textView.setTextSize(20);
        textView.setPadding(120,0);
    } else {
        textView = (TextView) view;
    }
    textView.setText(getChild(i,i1));
    return textView;
}

@Override
public boolean isChildSelectable(int i,int i1) {
    return true;
}
}

activity_main.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity">

<Spinner
    android:id="@+id/selector"
    android:layout_marginLeft="10dp"
    android:layout_width="match_parent"
    android:layout_height="50dp"/>

<ExpandableListView
    android:id="@+id/expandable_list_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

</LinearLayout>

header.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="20dp"
android:orientation="vertical">

<ImageView
    android:layout_width="match_parent"
    android:layout_height="200dp"
    app:srcCompat="@drawable/ic_launcher_foreground" />

<Button
    android:id="@+id/bt_expand"
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:text="+"
    android:textSize="30dp" />

</LinearLayout>
  1. 使用ViewPager作为子视图（ExpandableListView with ViewPager combination as its child）的ExpandableListView，使用Horizo​​ntalRecyclerView作为子视图（Expandable list view with HorizontalScroll View for child view）的ExpandableListView：使用以下方法之一，并将ExpandableListView的OnGroupExpandListener设置为仅扩展一个组，那么我认为没有必要使用当前的RecyclerView。
,

我终于通过使用下面的simeple代码解决了这个问题：

//AutoScroll for menu
    int t = 0,j,e=0,l=0;

    for (int n=0; n<=position;n++){

        e= e +objectMap.get(textHeaderlist.get(n)).size();
        l= l+450;
    }

    t=position+1;

    j= 200+e+t+l;
    scrollView.scrollTo(5,j);

这终于解决了我的问题。

无论哪种方式，谢谢！

androidandroidautoscrollexpandablelistviewsmooth-scrolling