问如何将集合转换为列表？此集合在Hashmap中用作键。
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Stack Overflow用户

提问于 2014-07-25 05:01:55

回答 1查看 124关注 0票数 1

你好，我在android中使用了一个可扩展的列表视图.为了填充列表，我使用了hashmap，因为我想将相应的类别映射到它的子目录。我的hashmap类似于Hashmap> .Now，使用了以下代码：

public class ExpandableListAdapter extends BaseExpandableListAdapter 
{

    private Context _context;
    // child data in format of header title, child title
    private Map<SaleDetailsMenuItems, List<ModifList>> _listDataChild;

    public ExpandableListAdapter(Context context, Map<SaleDetailsMenuItems, List<ModifList>> listChildData) 
    {
        this._context = context;
        this._listDataChild = listChildData;
    }
    @Override
    public Object getChild(int groupPosition, int childPosititon) 
    {
        Set<SaleDetailsMenuItems> s = _listDataChild.keySet();
        SaleDetailsMenuItems key = (SaleDetailsMenuItems) s.toArray()[groupPosition];
        //List<SaleDetailsMenuItems> list = new ArrayList<SaleDetailsMenuItems>(s);
        //Log.e("Child in adapter get Child","get child "+this._listDataChild.get(key).get(childPosititon));
        return this._listDataChild.get(key).get(childPosititon);
    }
    @Override
    public long getChildId(int groupPosition, int childPosition) 
    {
        return childPosition;
    }
    @Override
    public View getChildView(int groupPosition, final int childPosition,boolean isLastChild, View convertView, ViewGroup parent) 
    {

     String childText = ((ModifList)getChild(groupPosition, childPosition)).getName();
     String childText1 = "1";
     String childText2 = ((ModifList)getChild(groupPosition, childPosition)).getPrice();
        if (convertView == null) 
        {
            LayoutInflater infalInflater = (LayoutInflater) this._context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = infalInflater.inflate(R.layout.list_item, null);
        }

        TextView txtListChild = (TextView) convertView.findViewById(R.id.lblListItem);
        TextView txtListChild1 = (TextView) convertView.findViewById(R.id.lblListItem1);
        TextView txtListChild2 = (TextView) convertView.findViewById(R.id.lblListItem2);
        txtListChild.setText(childText);
        txtListChild1.setText(childText1);
        txtListChild2.setText(childText2);
        return convertView;

    }

    @Override
    public int getChildrenCount(int groupPosition)
    {
        SaleDetailsMenuItems key ;
        try
        {
            Set<SaleDetailsMenuItems> s = _listDataChild.keySet();
        key = (SaleDetailsMenuItems) s.toArray()[groupPosition];
        //  List<SaleDetailsMenuItems> list = new ArrayList<SaleDetailsMenuItems>(s);
            //Log.e("Child size in adapter ","get children count "+this._listDataChild.get(key).size());
            this._listDataChild.get(key).size();
        }
        catch(NullPointerException e)
        {
            e.printStackTrace();
            return 0;
        }
        return this._listDataChild.get(key).size();
    }

    @Override
    public Object getGroup(int groupPosition) 
    {
        Set<SaleDetailsMenuItems> s = _listDataChild.keySet();
        //List<SaleDetailsMenuItems> list = new ArrayList<SaleDetailsMenuItems>(s);
        SaleDetailsMenuItems key = (SaleDetailsMenuItems) s.toArray()[groupPosition];
        //Log.e("adapter get group ","get group "+key);
        return key;
    }

    @Override
    public int getGroupCount() 
    {
        //Log.e("Group Count","Group Count "+_listDataChild.keySet().size());
        return _listDataChild.keySet().size();
    }

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

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded,View convertView, ViewGroup parent) 
    {
         final int index = groupPosition;
        ExpandableListView mExpandableListView = (ExpandableListView) parent;
        mExpandableListView.expandGroup(groupPosition);

        if (convertView == null) 
        {
            LayoutInflater infalInflater = (LayoutInflater) this._context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = infalInflater.inflate(R.layout.list_group, null);
        }
        TextView lblListHeader = (TextView) convertView.findViewById(R.id.lblListHeader);
        TextView lblListHeader1 = (TextView) convertView.findViewById(R.id.lblListquantity1);
        TextView lblListHeader2 = (TextView) convertView.findViewById(R.id.lblListprice1);
        Button add = (Button) convertView.findViewById(R.id.btnadd);
        Button minus = (Button) convertView.findViewById(R.id.Button01);


        lblListHeader.setText(((SaleDetailsMenuItems) getGroup(groupPosition)).getName().toString());
        lblListHeader1.setText(((SaleDetailsMenuItems) getGroup(groupPosition)).getQuantity().toString());
        lblListHeader2.setText(((SaleDetailsMenuItems) getGroup(groupPosition)).getPrice().toString());
        minus.setOnClickListener(new OnClickListener() 
        {
            @Override
            public void onClick(View v) 
            {
                // TODO Auto-generated method stub
                listviewAdapter.notifyDataSetChanged();
                putminusquantity(index);
        //listviewAdapter.notifyDataSetChanged();
            }
        });

        add.setOnClickListener(new OnClickListener() 
        {
            @Override
            public void onClick(View v) 
            {
                // TODO Auto-generated method stub
                //Toast.makeText(context, shankar, Toast.LENGTH_SHORT).show();
                //DeleteOrderScreen del = new DeleteOrderScreen();
                listviewAdapter.notifyDataSetChanged();
                putaddquantity(index);
                //listviewAdapter.notifyDataSetChanged();
            }
        });
        return convertView;
    }
    @Override
    public boolean hasStableIds() 
    {
        return false;
    }
    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) 
    {
        return true;
    }
}

在这种情况下，set用于从Hashmap.as获取密钥集，set是无序的，我得到了无序的列表，.I想要有序的可扩展列表。那么如何安排我的单子呢？？请尽快回复我。

java

android

list

hashmap

expandablelistview

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回答 1

Stack Overflow用户

回答已采纳

发布于 2014-07-25 05:14:25

一种可能是您不使用HashMap或HashSet，而是使用TreeMap和TreeSet。您输入的对象中有一个正确的compareTo方法，或者您必须使用自定义比较器，这是您在TreeMap或TreeSet的构造函数中提供的。

然后对地图或集合进行排序:例如：

   // auto sorted because Integer implements Comparable
    SortedSet set = new TreeSet<Integer>();

   // asume MyObject implements Comparable
   SortedSet set = new TreeSet<MyObject>();

   // asume MyObject needs a special other sorting
   SortedSet set = new TreeSet<MyObject>(MyCustomComparator);