如何从Database和Listview中删除所选项目

Question

I want to delete selected item from listview and Database. I have write code for List-view and Database insertion.

But problem is with deletion i am using OnItemClick Listener for deletion of particular item.

And for deletion of item i pass Position variable to database delete method. It work but when you delete upper item of list and than you try to delete lower item it wont delete.

May be because I am passing position variable to database delete method.and in database i am checking it with primary key ID and after deletion of upper item Id of lower item does not change so this problem occurs

suggest me some good solution

Here is code fragment code

 public void onStart() {
   super.onStart();
   initfrag();}
private void initfrag() {
// TODO Auto-generated method stub
    dh = new com.myapp.database.DatabaseHelper(getActivity());
    nameArray   =   new  ArrayList<String>();
    db = new com.myapp.database.DatabaseHelper(getActivity());
    list = (ListView)getView().findViewById(R.id.fevlist);
    adapter=new ListAdapter(getActivity(), nameArray);
    Log.d("Reading: ", "Reading all contacts..");
     List<Fevorites> contacts = db.getAllContacts();     
     for (Fevorites cn : contacts) {
         s = "Name: " + cn.getID() + " ,Phone: " + cn.getPhoneNumber()+"\n";
         nameArray.add(s);
         list.setAdapter(adapter);     
             }
    list.setAdapter(adapter);
      list.setOnItemClickListener(new OnItemClickListener() {
          public void onItemClick(AdapterView adapterView, View view, int position, long id) {
        // TODO Auto-generated method stu   
         nameArray.remove(position);
         Toast t = Toast.makeText(getActivity(), nameArray.get(position), Toast.LENGTH_SHORT);
         t.show();
        // dh.Deleteitem();
            adapter.notifyDataSetChanged();
            adapter=new ListAdapter(getActivity(), nameArray);
         list.setAdapter(adapter);

    }
}); 
}

Here is Fevorites

public class Fevorites {
//private variables
int _id;
String _name;
String _phone_number;
// Empty constructor
public Fevorites(){
}
// constructor
public Fevorites(int id, String name, String _phone_number){
    this._id = id;
    this._name = name;
    this._phone_number = _phone_number;
}
// constructor
public Fevorites(String name, String _phone_number){
    this._name = name;
    this._phone_number = _phone_number;
}
// getting ID
public int getID(){
    return this._id;
}
// setting id
public void setID(int id){
    this._id = id;
}
// getting name
public String getName(){
    return this._name;
}
// setting name
public void setName(String name){
    this._name = name;
}

// getting phone number
public String getPhoneNumber(){
    return this._phone_number;
}

// setting phone number
public void setPhoneNumber(String phone_number){
    this._phone_number = phone_number;
}

}

Databasehelper class

public DatabaseHelper(Context context) {
    super(context,DATABASE_NAME , null,DATABASE_VERSION);
    // TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub

    String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "("
            + KEY_ID + " INTEGER PRIMARY KEY," + KEY_ARTIST + " TEXT,"
            + KEY_SONG + " TEXT" + ")";
    db.execSQL(CREATE_CONTACTS_TABLE);
}
public void addContact( ) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put(KEY_ARTIST, "XYZ  "); // Contact Name
    values.put(KEY_SONG, "XYZ testing "); // Contact Phone
    // Inserting Row
    db.insert(TABLE_CONTACTS, null, values);
    db.close(); // Closing database connection
}
public void Deleteitem(String string)
        {
    SQLiteDatabase db = this.getWritableDatabase();
    String query = "DELETE FROM favorite WHERE id="+string;
    db.execSQL(query);
        }
 // Getting All Contacts
public List<Fevorites> getAllContacts() {
    List<Fevorites> contactList = new ArrayList<Fevorites>();
    // Select All Query
    String selectQuery = "SELECT  * FROM " + TABLE_CONTACTS;
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);
    // looping through all rows and adding to list
    if (cursor.moveToFirst()) {
        do {
            Fevorites contact = new Fevorites();
            contact.setID(Integer.parseInt(cursor.getString(0)));
            contact.setName(cursor.getString(1));
            contact.setPhoneNumber(cursor.getString(2));
            // Adding contact to list
            contactList.add(contact);
        } while (cursor.moveToNext());
    }
    // return contact list
    return contactList;
}
Fevorites getContact(int id) {
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.query(TABLE_CONTACTS, new String[] { KEY_ID,
            KEY_SONG, KEY_ARTIST }, KEY_ID + "=?",
            new String[] { String.valueOf(id) }, null, null, null, null);
    if (cursor != null)
        cursor.moveToFirst();
    Fevorites contact = new Fevorites(Integer.parseInt(cursor.getString(0)),
            cursor.getString(1), cursor.getString(2));
    // return contact
    return contact;
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub
}

Here is Custom List adaptor class

* List adapter class *

public class ListAdapter extends BaseAdapter {
private Activity activity;
private ArrayList<String> name;
private static LayoutInflater inflater=null;

public ListAdapter(Activity a, ArrayList<String> nameArray) {
    activity = a;
    name    =   nameArray;
    inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public int getCount() {
    return name.size();
}
public Object getItem(int position) {
    return position;
}
public long getItemId(int position) {
    return position;
}
public static class ViewHolder{
    public TextView text;
}
public View getView(int position, View convertView, ViewGroup parent) {
    View vi=convertView;
    ViewHolder holder;
    if(convertView==null){
        vi = inflater.inflate(R.layout.fevorites_list, null);
        holder=new ViewHolder();
        holder.text=(TextView)vi.findViewById(R.id.list_item_entry_title);
        vi.setTag(holder);
    }
    else
        holder=(ViewHolder)vi.getTag();
    holder.text.setText(name.get(position));
    return vi;
}

}

Answer 1

Normally , you retreive a List of some kind of Objects ( let's say in your case : List of favorites ) , then you pass it to your adapter to display it in a ListView . so your CustomAdapter will be like this :

public class ListAdapter extends BaseAdapter {
private Context context;
private ArrayList<Favorites> items;
private LayoutInflater inflater=null;

public ListAdapter(Context context, ArrayList<Favorites> items) {
    this.context = context;
    this.items   =   items;
    inflater = LayoutInflater.from(context);
}
public int getCount() {
    return items.size();
}
public Favorites getItem(int position) {
    return items.get(position);
}
public long getItemId(int position) {
    return items.get(position).getId();
}
public static class ViewHolder{
    public TextView text;
}
public View getView(int position, View convertView, ViewGroup parent) {
    View vi=convertView;
    ViewHolder holder;
    if(convertView==null){
        vi = inflater.inflate(R.layout.fevorites_list, parent, false);
        holder=new ViewHolder();
        holder.text=(TextView)vi.findViewById(R.id.list_item_entry_title);
        vi.setTag(holder);
    }
    else 
         holder=(ViewHolder)vi.getTag();

    holder.text.setText(items.get(position).getName());
    return vi;


   }
 }

and then , instanciate the adapter and pass it to your listView like this :

//retreive the list of contacts
List<Fevorites> contacts = db.getAllContacts(); 
ListAdapter adapter = new ListAdapter(ActivityName.this , contacts);
list.setAdapter(adapter);

NB : replace the ActivityName by the name of your activity