android – 从多个选择ListView返回值

我试图允许用户从清单中选择一些目录,并在点击“提交”按钮时返回.这是我的代码片段.它使用/ sdcard /上的所有目录填充ListView,并在提交时初始选择(我选择的是多少),日志显示返回的正确选择.但是,如果我取消选中项目,然后再次单击“提交”,它仍然显示为全部被选中.我需要写一个处理程序来取消选中项目吗？我以为这是由choiceMode选择照顾的？谢谢！

private SparseBooleanArray a;    
directoryList.setAdapter(new ArrayAdapter<String>(this,android.R.layout.simple_list_item_multiple_choice,directoryArray));
    submitButton = (Button)findViewById(R.id.submi@R_675_11164@utton);
    submitButton.setOnClickListener(new OnClickListener()
        {
        @Override
        public void onClick(View v)
        {
            a = new SparseBooleanArray();
            a.clear();
            a = directoryList.getcheckedItemPositions();

            for (int i = 0; i < a.size(); i++)
            {
                //added if statement to check for true. The SparseBooleanArray
                //seems to maintain the keys for the checked items,but it sets
                //the value to false. Adding a Boolean check returns the correct result.                    
                if(a.valueAt(i) == truE)
                    Log.v("Returned ",directoryArraY[a.keyAt(i)]);

            }                
        }
    });