android adaptor row hiding

问题

In arrayAdptor we use following code:

 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;

Now suppose some value are null (for example at position 2 , items[2] = null ) so i dont want to show it in row. i want to hide it. if i use

               row.setVisibility(View.GONE)

it leaves a blank space at this row which i dont want. so what should i do?

回答1:

You'll need to have the adapter return the total number of non-null items with getCount and then keep a mapping of position to your internal data structure.

For example. You have a list

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

When getCount is called it returns 3.

Then when getView is called on position 1 you return the item at list[1]. getView on position 2 returns list[3] (as it's the 2nd non-null), and so forth.

This is the only way I've found to do this.

回答2:

AFAIK you can't return a null view from getView, but you could just make the view invisible and height 1. Although manipulating using the getCount is probably the preferred way.

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

回答3:

You can use a View that has no height for the "hidden" items so that you don't have to do all the model housekeeping and mapping. For example, suppose you had a "filter" EditText field that when data is entered it only keeps matching items:

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);

    ...
}

回答4:

Here you need to write the logic in your getCount(),getItemId() and getItem(),
It will create the no of rows what the getCount return

//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)
        }

And

//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  
    }

Edit:So in your getview

 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
        ----
}

回答5:

This is the solution I implemented, here is a code example for everyone that is looking it:

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

 }

hope this helps!

来源：https://stackoverflow.com/questions/6907891/android-adaptor-row-hiding

标签

android

adapter