自定义ListView带复选框：在代码中使用所选项

Question

我创建了一个带复选框的CustomListView。如何创建代码，以便我可以在代码中使用ListView的选定项。此代码已被建议： 主要活动代码：

ArrayList<PeopleDetails> people_selected = new ArrayList<PeopleDetails>();
        peoplelist_customadapter adapter = (peoplelist_customadapter) people_list.getAdapter();
        StringBuilder test_builder = new StringBuilder();
        for(int i=0; i < adapter.checkstates.size() ; i++){
               if(adapter.checkstates.get(i) == true){
                   people_selected.add(people_details.get(i));///lines throws error java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
                   ///so people_details is empty - 0 entries. why???
                   test_builder.append(people_details.get(i).name);

               }

适配器：

package com.example.partyorganiser;

import java.util.ArrayList;

import android.app.Activity;
import android.content.Context;
import android.util.SparseBooleanArray;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.ImageView;
import android.widget.TextView;

public class peoplelist_customadapter extends ArrayAdapter<PeopleDetails> implements CompoundButton.OnCheckedChangeListener{

    Context context; 
    int layoutResourceId;    
    ArrayList<PeopleDetails> data = null;
    SparseBooleanArray checkstates;

    public peoplelist_customadapter(Context context, int layoutResourceId, ArrayList<PeopleDetails> data) {
        super(context, layoutResourceId, data);
        this.layoutResourceId = layoutResourceId;
        this.context = context;
        this.data = data;
        checkstates = new SparseBooleanArray(data.toArray().length);

    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row = convertView;
        personHolder holder = null;
        PeopleDetails[] people_array = data.toArray(new PeopleDetails[data.size()]);


        if(row == null)
        {
            LayoutInflater inflater = ((Activity)context).getLayoutInflater();
            row = inflater.inflate(layoutResourceId, parent, false);

            holder = new personHolder();
            holder.txtName = (TextView)row.findViewById(R.id.name_txt);
            holder.txtNumber = (TextView)row.findViewById(R.id.number_txt);
            holder.checkbox = (CheckBox) row.findViewById(R.id.checkBox);
            ///holder.chkSelect.setTag(position);
            ///holder.chkSelect.setChecked(mCheckStates.get(position, false));
            ///holder.chkSelect.setOnCheckedChangeListener(this);
            holder.checkbox.setTag(position);
            holder.checkbox.setOnCheckedChangeListener((new CompoundButton.OnCheckedChangeListener() {
                public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

                }
            }));
            row.setTag(holder);
        }
        else
        {
            holder = (personHolder)row.getTag();
        }

        PeopleDetails person = people_array[position];
        holder.txtName.setText(person.name);
        holder.txtNumber.setText(person.number);
        holder.checkbox.setChecked(checkstates.get(position, false));
        holder.checkbox.setOnCheckedChangeListener(this);
        return row;
    }
    public boolean isChecked(int position) {
        return checkstates.get(position, false);
    }

    public void setChecked(int position, boolean isChecked) {
        checkstates.put(position, isChecked);

    }
    public void onCheckedChanged(CompoundButton buttonView,boolean isChecked) {
         checkstates.put((Integer) buttonView.getTag(), isChecked);    

    }



    static class personHolder
    {
        TextView txtName;
        TextView txtNumber;
        CheckBox checkbox;
        public boolean isChecked(){
            boolean isChecked_boolean = false; ///this holds the return value, of whether the checkbox is checked or not.
            if(checkbox.isChecked()){
                isChecked_boolean = true;
            }
            else{
                isChecked_boolean = false;
            }
            return isChecked_boolean;
        }
    }
}





            }

但是没有用，因为文件应该被写入时为空。这段代码有错误吗？有没有更好的方法来实现这个目标？

感谢您的帮助!!