ExpandableList未在ScrollView内展开

以前我对父视图和子视图使用LinearLayout，并通过单击可扩展列表父视图时使用以下代码片段进行扩展：

subtask_explist.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {
        @Override
        public boolean onGroupClick(ExpandableListView parent, View v,
                                    int groupPosition, long id) {
            Log.d("subtask_explist" , " pressed");
            setListViewHeight(parent, groupPosition);
            return false;
        }
    });
private void setListViewHeight(ExpandableListView listView,
                               int group) {
    ExpandableListAdapter listAdapter = (ExpandableListAdapter) listView.getExpandableListAdapter();
    int totalHeight = 0;
    int desiredWidth = View.MeasureSpec.makeMeasureSpec(listView.getWidth(),
            View.MeasureSpec.EXACTLY);
    for (int i = 0; i < listAdapter.getGroupCount(); i++) {
        View groupItem = listAdapter.getGroupView(i, false, null, listView);
        groupItem.measure(desiredWidth, View.MeasureSpec.UNSPECIFIED);
        totalHeight += groupItem.getMeasuredHeight();
        if (((listView.isGroupExpanded(i)) && (i != group))
                || ((!listView.isGroupExpanded(i)) && (i == group))) {
            for (int j = 0; j < listAdapter.getChildrenCount(i); j++) {
                View listItem = listAdapter.getChildView(i, j, false, null,
                        listView);
                listItem.measure(desiredWidth, View.MeasureSpec.UNSPECIFIED);
                totalHeight += listItem.getMeasuredHeight();
            }
        }
    }
    ViewGroup.LayoutParams params = listView.getLayoutParams();
    int height = totalHeight
            + (listView.getDividerHeight() * (listAdapter.getGroupCount() - 1));
    if (height < 10)
        height = 200;
    params.height = height;
    listView.setLayoutParams(params);
    listView.requestLayout();
}

旧布局文件为：

child_row_ad_subtask.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android:id="@+id/LinearLayout01"
android:layout_width="fill_parent"
android:layout_height="56dp"
android:background="@color/white_color"
xmlns:android="http://schemas.android.com/apk/res/android">
<CheckBox
    android:layout_width="wrap_content"
    android:layout_height="56dp"
    android:layout_gravity="center_vertical"
    android:layout_marginRight="5dp"
    android:layout_marginLeft="10dp"
    android:focusable="false"
    android:id="@+id/cb_subtask" />
<TextView
    android:id="@+id/tv_subtask"
    android:layout_width="wrap_content"
    android:layout_height="56dp"
    android:layout_marginLeft="5dp"
    android:layout_gravity="center_vertical"
    android:text="Single-line item"
    android:gravity="center_vertical"
    android:paddingLeft="5dip"
    android:textColor="#000000"
    android:textStyle="normal"
    android:textSize="17dip"
    android:clickable="false">
</TextView>
</LinearLayout>

现在我已经更新了我的代码，并将根布局"LinearLayout"更改为"Relative layout"：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:paddingLeft="16dp"
android:paddingRight="16dp"
android:layout_width="match_parent"
android:layout_height="56dp"
android:background="@color/white_color"
android:id="@+id/LinearLayout01">
<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">
<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="match_parent">
    <android.support.v7.widget.AppCompatCheckBox
            android:id="@+id/cb_subtask"
            android:layout_gravity="center_vertical"
            android:focusable="false"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>
</LinearLayout>
    <android.support.v7.widget.AppCompatTextView
        android:id="@+id/tv_subtask"
        android:paddingLeft="56dp"
        android:paddingTop="17dp"
        android:textSize="16sp"
        android:paddingBottom="20dp"
        android:textColor="#000000"
        android:clickable="false"
        android:text="Single Line Item "
        android:layout_width="wrap_content"
        android:layout_height="56dp"
        />
</RelativeLayout>
</LinearLayout>

现在相同的方法setListViewHeight（parent，groupPosition）；不工作，给出错误：

FATAL EXCEPTION: main java.lang.NullPointerException
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:500)
at android.view.View.measure(View.java:15349)
at com.ujjawal.test.testdesignapplication.MainActivity.setListViewHeight(MainActivity.java:227)
at com.ujjawal.test.testdesignapplication.MainActivity.access$000(MainActivity.java:21)
at com.ujjawal.test.testdesignapplication.MainActivity$2.onGroupClick(MainActivity.java:126)
at android.widget.ExpandableListView.handleItemClick(ExpandableListView.java:561)
at android.widget.ExpandableListView.performItemClick(ExpandableListView.java:539)
at android.widget.AbsListView$PerformClick.run(AbsListView.java:2859)
at android.widget.AbsListView$1.run(AbsListView.java:3533)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4802)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:813)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:580)
at dalvik.system.NativeStart.main(Native Method)

我有3个可扩展列表，一个在另一个下面，在相同的布局中，如果我删除滚动视图，一切都很好，但在扩展列表上没有滚动视图，下面的其他列表就会离开屏幕。

我想要所有3个列表视图都有扩展行为。

提前感谢：）