突出显示可展开列表中的选定项目

Question

我有一个布局,我在左边的片段中有一个可扩展列表,右边有一个细节片段.一切正常.

现在我想说明左边的哪个项目正在显示右边的详细信息,这里我遇到了问题.

在普通列表视图中,我通过将列表视图的选择模式设置为单个,然后使用基于"激活"状态的可绘制状态来实现此目的.当我单击该项目时,背景将设置为我选择的颜色并保持这种状态,直到我在列表中选择另一个项目.

我试着将它应用到我的可扩展列表视图中,这是一个令人沮丧的失败.没有错误,但所选项目没有保持其颜色状态.我不确定我是不是正确设置了它的选择模式(我已经在布局文件中尝试了它以及编程方式,它似乎没有什么区别),或者指向错误的东西(不知道那是怎么回事,但......)

任何帮助/指示赞赏(即使它是在一个完全不同的方向).

目前大多数失败:

可扩展的列表视图代码

private void fillData(String group, String child) {
    ExpandableListView lv;
    mGroupsCursor = mDbHelper.fetchGroup(group);
    getActivity().startManagingCursor(mGroupsCursor);
    mGroupsCursor.moveToFirst();
    lv = (ExpandableListView) getActivity().findViewById(R.id.explist);
    lv.setChoiceMode(ExpandableListView.CHOICE_MODE_SINGLE);        

    mAdapter = new MyExpandableListAdapter(mGroupsCursor, getActivity(),
            R.layout.explistlayout,
            R.layout.explistlayout,
            new String[] { "_id" },
            new int[] { android.R.id.text1 },
            new String[] { child },
            new int[] { android.R.id.text1 });
    lv.setAdapter(mAdapter);
    registerForContextMenu(lv);

    lv.setOnChildClickListener(new ExpandableListView.OnChildClickListener() { 
        @Override 
        public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id)  
        { 
            mRowId  = id;
            EventDisplayFragment eventdisplay = new EventDisplayFragment();
            getFragmentManager().beginTransaction().replace(R.id.rightpane, eventdisplay).commit();
            return true; 
        } 
        }); 
}

public class MyExpandableListAdapter extends SimpleCursorTreeAdapter {

    public MyExpandableListAdapter(Cursor cursor, Context context,
            int groupLayout, int childLayout, String[] groupFrom,
            int[] groupTo, String[] childrenFrom, int[] childrenTo) {
        super(context, cursor, groupLayout, groupFrom, groupTo,
                childLayout, childrenFrom, childrenTo);
    }
    @Override
    protected Cursor getChildrenCursor(Cursor groupCursor) {
        Cursor childCursor = mDbHelper.fetchChildren(mGroup, groupCursor
                .getString(groupCursor
                        .getColumnIndex(AttendanceDB.EVENT_ROWID)));
        getActivity().startManagingCursor(childCursor);
        childCursor.moveToFirst();
        return childCursor;
    }
}

item_selector.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item 
     android:state_pressed="true" 
     android:drawable="@color/green" />
    <item 
     android:state_selected="true" 
     android:drawable="@color/blue" />
    <item 
     android:state_focused="true" 
     android:drawable="@color/violet" />
    <item 
     android:state_activated="true" 
     android:drawable="@color/blue" />
</selector>

Answer 1

在ExpandableListView上执行以下操作:

步骤1.将选择模式设置为单个(可以在xml中完成为android:choiceMode ="singleChoice")

步骤2.使用选择器xml作为背景(android:listSelector ="@ drawable/selector_list_item")

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android"
   android:exitFadeDuration="@android:integer/config_mediumAnimTime">

   <item android:drawable="@android:color/holo_blue_bright" android:state_pressed="true"/>
   <item android:drawable="@android:color/holo_blue_light" android:state_selected="true"/>
   <item android:drawable="@android:color/holo_blue_dark" android:state_activated="true"/>

</selector>

步骤3.呼叫expandableListView.setItemChecked(指数,真正的)在onChildClick()回调.

index是如下计算的子项的基于0的索引

第1组 [指数= 0]

• 儿童项目1
• 儿童项目2
• 子项3 [index = 3]

第2组 [指数= 4]

• 儿童项目1
• 儿童项目2
• 子项目3 [索引= 7]

第3组 [指数= 8]

• 儿童项目1
• 儿童项目2
• 子项目3 [索引= 11]

如果我们也有列表标题,它们也会考虑索引值.

这是一个工作示例:

@Override
public boolean onChildClick(ExpandableListView parent, View v,
        int groupPosition, int childPosition, long id) {
    ...

    int index = parent.getFlatListPosition(ExpandableListView.getPackedPositionForChild(groupPosition, childPosition));
    parent.setItemChecked(index, true);


    return true;
}

Answer 2

花了3-4个小时之后,它变得如此简单,不需要创建额外的XML文件,只需检查是否扩展了组项目,如果是,则选择颜色,在else语句中使它们按原样生成....

@Override
//in this method you must set the text to see the parent/group on the list
public View getGroupView(final int i, boolean b, View view, ViewGroup viewGroup) {

    if (view == null) {
        view = inflater.inflate(R.layout.list_item_parent, viewGroup,false);
    }

    if(b){
        view.setBackgroundResource(R.color.waterblue);
    }else{
        view.setBackgroundColor(color.transparent);
    }


    //return the entire view
    return view;
}

Answer 3

我终于想出了如何使这项工作(对我而言).这似乎是一个黑客攻击,但这是我唯一能够为此工作的东西.

基本上我创建了一个二维数组来保存子项的选定状态,在适配器构造函数中初始化它,然后我在我的getChildView方法中引用它(如果当前选中的子项滚动出视图)和我的onChildClick方法(更改当前选择并关闭旧的).

private selectedStatus[][];  // array to hold selected state
private View oldView;        // view to hold so we can set background back to normal after selection of another view

构造 函数初始化数组

    public MyExpandableListAdapter(Cursor cursor, Context context,
            int groupLayout, int childLayout, String[] groupFrom,
            int[] groupTo, String[] childrenFrom, int[] childrenTo) {
        super(context, cursor, groupLayout, groupFrom, groupTo,
                childLayout, childrenFrom, childrenTo);
        selectedStatus = new boolean[cursor.getCount()][];
        for (int i = 0; i < cursor.getCount(); i++) {
            cursor.moveToPosition(i);
            Cursor childCheckCursor = mDbHelper.fetchChildren(mGroup,
                    cursor.getString(cursor
                            .getColumnIndex(AttendanceDB.EVENT_ROWID)));
            getActivity().startManagingCursor(childCheckCursor);
            selectedStatus[i] = new boolean[childCheckCursor.getCount()];
            for (int j = 0; j < childCheckCursor.getCount(); j++) {
                selectedStatus[i][j] = false;
            }
        }

    }

当孩子滚出视野时需要getChildView

    @Override 
    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) { 
        final View v = super.getChildView(groupPosition, childPosition, isLastChild, convertView, parent); 
        if(selectedStatus[groupPosition][childPosition] == true){
            v.setBackgroundResource(R.color.blue);                          
        } else {
            v.setBackgroundResource(R.color.black);
        }
        return v; 
    } 

onChildClick 更改所选项目

    lv.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
        @Override
        public boolean onChildClick(ExpandableListView parent, View v,
                int groupPosition, int childPosition, long id) {
            mRowId = id;
            EventDisplayFragment eventdisplay = new EventDisplayFragment();
            getFragmentManager().beginTransaction()
                    .replace(R.id.rightpane, eventdisplay).commit();
            if(oldView != null){
                oldView.setBackgroundResource(R.color.black);   // change the background of the old selected item back to default black                 }
            oldView = v;                                        // set oldView to current view so we have a reference to change back on  next selection
            for (int i = 0; i < selectedStatus.length; i++) {
                for (int j = 0; j < checkedStatus[i].length; j++) {
                    if(i == groupPosition && j == childPosition){  // set the current view to true and all others to false
                        selectedStatus[i][j] = true;
                    } else {
                        selectedStatus[i][j] = false;
                    }
                }
            }
            v.setBackgroundResource(R.color.blue);
            return true;
        }
    });