单击删除按钮时如何刷新列表视图

Question

我已删除适配器类中的编码，如下所示：

delBtn=(ImageButton) v.findViewById(R.id.del_btn);  
delBtn.setOnClickListener(new View.OnClickListener() {

    @Override
    public void onClick(View v) {
        sqlCon.deleteItem(id);          
    }
}); 

以下是 sqliteconnection类中的代码，

public void deleteItem(long id) {
    System.out.println("DELETE ");
    db = sqlHp.getWritableDatabase();
    db.delete(ItemDb.TABLE, "_id="+id , null);
    db.close();
}   

点击删除按钮后，如何刷新列表视图？感谢。

修改 * 在A级 *

 public Cursor getAllItem(String user) {

    String[] userID = new String[] {user};


    db = sqlHp.getReadableDatabase();       
    cur=db.query(ItemDb.TABLE, null, "user=?", userID, null, null, "name");     
    return cur;

}

public Cursor getOneItem(long id) {
    db = sqlHp.getReadableDatabase();
    cur=db.query(ItemDb.TABLE, null, "_id="+ id, null, null, null,null);
    return cur;
}

C类：

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState); 

        String[] from = new String[] { ItemDb.NAME, ItemDb.CONDITION, ItemDb.EMAIL};
        int[] to = new int[] { R.id.etItemName, R.id.etItemCondition, R.id.etEmail };
        itemAdapter = new ItemAdapter(this,R.layout.list_item, null, from, to);
        this.setListAdapter(itemAdapter);

        UserName = (String) getIntent().getSerializableExtra("UserName");

        SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
        SharedPreferences.Editor editor = settings.edit();
        editor.putString("UserName", UserName); // here string is the value you want to save
        editor.commit();                  
        Log.i(Tag, "UserName1: "+ UserName);
    }

C类的另一部分

@Override
    protected void onResume() {
        super.onResume();
        new GetItem().execute((Object[]) null);
    }

    @SuppressWarnings("deprecation")
    @Override
    protected void onStop() {
        Cursor cursor = itemAdapter.getCursor();

        if (cursor != null)
            cursor.deactivate();

        itemAdapter.changeCursor(null); 
        super.onStop();

    }

    private class GetItem extends AsyncTask<Object, Object, Cursor> {
        ItemSQLiteConnector dbConnector = new ItemSQLiteConnector(ItemActivity.this);

        @Override
        protected Cursor doInBackground(Object... params) {
            return dbConnector.getAllItem(UserName);
        }

        @Override
        protected void onPostExecute(Cursor result) {
            itemAdapter.changeCursor(result);           
        }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_item, menu);      
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {       
        Intent addItem = new Intent(ItemActivity.this, AddEditItem.class).setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

        startActivity(addItem);     
        return super.onOptionsItemSelected(item);

    }

}

B组：

public class ItemAdapter extends SimpleCursorAdapter {

    private int layout;
    private ImageButton editBtn;
    private ImageButton delBtn;
    ImageButton addBtn;
    String selection, UserName;
    LayoutInflater inflator;
    final ItemAdapter myadapter = this;
    private SQLiteDatabase db;



    public ItemAdapter(Context context, int layout, Cursor c,String[] from, int[] to) {
        super(context, layout, c, from, to,0);
        this.layout = layout;
        inflator= LayoutInflater.from(context);


    }

    public View newView(Context context, Cursor cursor, ViewGroup parent) {     
        View v = inflator.inflate(layout, parent, false);       
        return v;

    }

    @Override
    public void bindView(View v, final Context context, Cursor c) {
        final int id = c.getInt(c.getColumnIndex(ItemDb.ID));
        final String user = c.getString(c.getColumnIndex(ItemDb.USER));
        final String name = c.getString(c.getColumnIndex(ItemDb.NAME));
        final String condition = c.getString(c.getColumnIndex(ItemDb.CONDITION));
        final String email = c.getString(c.getColumnIndex(ItemDb.EMAIL));
        final String category = c.getString(c.getColumnIndex(ItemDb.CATEGORY));
        final byte[] image = c.getBlob(c.getColumnIndex(ItemDb.IMAGE));
        ImageView iv = (ImageView) v.findViewById(R.id.photo);

        if (image != null) {
            if (image.length > 3) {
                iv.setImageBitmap(BitmapFactory.decodeByteArray(image, 0,image.length));
            }
        }

        TextView tname = (TextView) v.findViewById(R.id.name);
        tname.setText(name);
        TextView tcondition = (TextView) v.findViewById(R.id.condition);
        tcondition.setText(condition);
        TextView temail = (TextView) v.findViewById(R.id.email);
        temail.setText(email);



        final ItemSQLiteConnector sqlCon = new ItemSQLiteConnector(context);

        editBtn=(ImageButton) v.findViewById(R.id.edit_btn);    
        editBtn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent intent=new Intent(context, AddEditItem.class).setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);               
                intent.putExtra("id", id);
                intent.putExtra("user", user);
                intent.putExtra("name", name);
                intent.putExtra("condition", condition);
                intent.putExtra("email", email);
                intent.putExtra("category", category);
                intent.putExtra("blob", image);
                context.startActivity(intent);
            }

        });

        delBtn=(ImageButton) v.findViewById(R.id.del_btn);  
        delBtn.setOnClickListener(new View.OnClickListener() {


            @Override
            public void onClick(View v) {
                sqlCon.deleteItem(id);      
                //Cursor cur=db.query(ItemDb.TABLE, null, "_id="+ id, null, null, null,null);   
                //myadapter.changeCursor(cur);
                //myadapter.notifyDataSetChanged();

                //Intent intent=new Intent(context,Tab.class).setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                //context.startActivity(intent);        
            }

        });     


        v.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {

                Intent intent=new Intent(context,ViewItem.class).setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);               
                intent.putExtra("id", id);
                intent.putExtra("user", user);
                intent.putExtra("name", name);
                intent.putExtra("condition", condition);
                intent.putExtra("email", email);
                intent.putExtra("category", category);
                intent.putExtra("blob", image);
                context.startActivity(intent);
            }
        });

    }

}

Answer 1

在删除sql并从适配器中删除项目之后，

调用notifyDataSetChanged()（来自适配器对象或适配器类）。

示例：

WhateverMyAdapterClassIs myadapter = new WhateverMyAdapterClassIs();

...

delBtn=(ImageButton) v.findViewById(R.id.del_btn);  
delBtn.setOnClickListener(new View.OnClickListener() {
     @Override
     public void onClick(View v) {
          sqlCon.deleteItem(id);

          //Add code to remove the respective item from the List,ArrayList 
          //or whatever you use in the adapter then call notifyDataSetChanged()

          myadapter.notifyDataSetChanged();
     }

}); 

或者，如果您已扩展了适配器类，请添加removeItem函数并从中调用notifyDataSetChanged：

public void removeItem(int index) {
    myList.remove(index);
    notifyDataSetChanged();
}

在您的情况下使用：

final ItemAdapter myadapter = this;

delBtn=(ImageButton) v.findViewById(R.id.del_btn);  
delBtn.setOnClickListener(new View.OnClickListener() {
     @Override
     public void onClick(View v) {
          sqlCon.deleteItem(id);

          //Add code to remove the respective item from the List,ArrayList 
          //or whatever you use in the adapter then call notifyDataSetChanged()

          myadapter.notifyDataSetChanged();
     }

}); 

Answer 2

public class ItemAdapter extends SimpleCursorAdapter {

private int layout;
private ImageButton editBtn;
private ImageButton delBtn;
ImageButton addBtn;
String selection, UserName;
LayoutInflater inflator;
final ItemAdapter myadapter = this;
private SQLiteDatabase db;
private OnItemDeleted mOnItemDeleted;

public interface OnItemDeleted {
    public void updateCursor();
}

public ItemAdapter(Context context, int layout, Cursor c,
                    String[] from, int[] to, OnItemDeleted onItemDeleted) {
    super(context, layout, c, from, to,0);
    this.layout = layout;
    mOnItemDeleted = onItemDeleted;
    inflator= LayoutInflater.from(context);
}

.........

delBtn=(ImageButton) v.findViewById(R.id.del_btn);  
    delBtn.setOnClickListener(new View.OnClickListener() {


        @Override
        public void onClick(View v) {
            sqlCon.deleteItem(id);      
            mOnItemDeleted.updateCursor();

            //Intent intent=new Intent(context,Tab.class).setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            //context.startActivity(intent);        
        }

    }); 
}

在调用类C

中

itemAdapter = new ItemAdapter(this,R.layout.list_item, null, from, to, new MyOnItemDeleted());
......
public class MyOnItemDeleted implements ItemAdapter.OnItemDeleted
{
    public void updateCursor()
    {
                 new GetItem().execute((Object[]) null);
    }
}