在列表视图中处理选中然后未选中的复选框的值

Question

In my activity I have 4 items in a list view with checkboxes in each row. After I leave activity I want all the checked item position numbers in an arraylist. This code works fine when user clicks all the checkboxes ones and leave the activity. But when user clicks a checkbox and then unchecks it, item position is arraylist doesnt able to clear. This methood is in my CustomAdapter class.

class GameAdapter extends BaseAdapter{
      private ArrayList<Integer> positions = new ArrayList<Integer>();

      public ArrayList<Integer> getPositions() {
          return positions;
      }

      getView(....){
         final ViewHolder holder;
         holder.checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

                if(holder.checkBox.isChecked()) {

                    positions.add(position);

                }
            }
        });
    }
}

I am handling this adapter class in the activity where my listview resides. There I am taking this arraylist values like this

ArrayList<Integer> gamePositions = mGameAdapter.getPositions();
String itemNumbers = gamePositions.toString();

in itemNumber string I want all the checked item number values.

Thank you in advance for guidance....

Answer 1

Follow below approach.

• Use HashMap instead of Arraylist, like below

    HashMap<Integer,Boolean> mapOfSelection = new HashMap<>(); 

• before onClick method, assign position to the checkbox, like below.

    holder.checkbox.setTag(position); 

• In onClick, do the following.

    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { mapOfSelection.put((Integer)buttonView.getTag(),isChecked); // True if this position/value is checked, false otherwise. } 

• Now when you need the selected items, just loop through the hashmap and check the positions/Key which have True value.

Answer 2

Replace this

if(holder.checkBox.isChecked()) {

  positions.add(position);
}

with this

 if(holder.checkBox.isChecked()) {
     if(!positions.contains(position))
        positions.add(position);

 } else {
     if(positions.contains(position))
         positions.remove(position);

 }