Android 适配器行隐藏

Question

在 arrayAdptor 中，我们使用以下代码：

 final LayoutInflater inflater = activity.getLayoutInflater();
    row = (LinearLayoutCustom) inflater.inflate(R.layout.row, null);
    final TextView label = (TextView) row.findViewById(R.id.title);
    label.setText(position + "" + items[position]); 
    return row;

现在假设某些值为 null （例如在位置 2 ， items[2] = null ），所以我不想在行中显示它。我想隐藏它。如果我使用

               row.setVisibility(View.GONE) 

它，则会在这一行留下我不想要的空白。那我该怎么办呢？

Answer 1

AFAIK，您不能从 getView 返回空视图，但您可以使视图不可见且高度为 1。尽管使用 getCount 进行操作可能是首选方式。

view.setVisibility(View.INVISIBLE);
view.getLayoutParams().height = 1;

Answer 2

您需要让适配器使用 getCount 返回非空项的总数，然后保留位置到内部数据结构的映射。

例如。
您有一个列表

1 - John
2 - null
3 - Bill
4 - Susan
5 - null

，当调用 getCount 时，它返回 3。

然后，当在位置 1 上调用 getView 时，您将返回 list[1] 处的项目。
位置 2 上的 getView 返回 list[3] （因为它是第二个非空），
等等。

这是我发现的唯一方法。

Answer 3

您可以使用没有“隐藏”项目高度的视图，这样您就不必执行所有模型管理和映射。例如，假设您有一个“过滤器”EditText 字段，当输入数据时，它仅保留匹配的项目：

public View getView(int position, View convertView, ViewGroup parent) {
    LayoutInflater   inflater = (LayoutInflater) MyActivity.this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    RelativeLayout view = (RelativeLayout) inflater.inflate(R.id.myListLayout, null, false);

    ...

    // if we didn't match filter be GONE and leave
    if (filterText.length() > 0 && myModelValueAtPosition.toLowerCase().indexOf(filterText) < 0){
        view = (RelativeLayout) inflater.inflate(R.layout.myListLayoutWithZeroHeight, null, false);
        view.setVisibility(View.GONE); // this doesn't really do anything useful; I'd hoped it would work by itself, but turns out the zero height layout is the key
        return view;
    }
    view.setVisibility(View.VISIBLE);

    ...
}

Answer 4

在这里，您需要在 getCount()< 中编写逻辑/a>,getItemId() 和 <一个href="http://developer.android.com/reference/android/widget/Adapter.html#getItem%28int%29" rel="nofollow">getItem(),
它将创建 getCount 返回的行数

//How many items are in the data set represented by this Adapter
    public int getCount() {
            return //Should return the count of rows you need to display (here the count excluding null values)
        }

并

//This need to return data item associated with the specified position in the data set.
public Object getItem(int position) {
        return //Return the object need to display at position, need the logic to skip null value  
    }

编辑：所以在您的 getview 中

 public View getView(int position, View convertView, ViewGroup parent) { 
         ---- 
        getItem(position);//Object corresponding to position ,In your case it will not be null since you need to write the logic to skip null object at getItem
        ----
}

Answer 5

这是我实现的解决方案，这里有一个代码示例供每个正在寻找它的人使用：

class Shipment_Adapter extends ArrayAdapter<Shipment>{
     ....
     ArrayList<Integer> emptyPositions = new ArrayList<>();

     public Shipment_Adapter(Context context, int shipment_row, Shipment[] myShipments){
        super(context, R.layout.shipment_row,myShipments);

        //populate emptyPositions list
        for(int i = 0; i< myShipments.length; i++){
            if(myShipments[i]==null){
                emptyPositions.add(i);
            }
        }

        this.mShipment = myShipments;
        this.mContext = context;
    }

    //corrects size of List
    @Override
    public int getCount() {
        return (mShipment.length - emptyPositions.size());
    }

    //recursive function that checks if position is not empty until it isn't
    public int isEmpty(int positiontocheck){
         int newposition;
         if(emptyPositions.contains(positiontocheck)){
             //true? check that next one is free
            return isEmpty(positiontocheck+1);
         }else{
            newposition = positiontocheck;
         }

         return newposition;
     }
}

public View getView(int position, View convertView, ViewGroup parent) {

    //now just need to use isEmpty to get the next not empty position in 
    //case our real position is empty

    position= isEmpty(position);

    Shipment shipment = mShipment[position];

    ...//and so on

 }

希望这会有所帮助！