Android适配器NotifyDataSetChanged不工作[关闭]

Question

我想在删除一个项目后刷新我的列表视图。即使我正在使用 notifyDataSetChanged 它仍然没有立即更新。我需要回去重新回到这个意图。需要帮忙。提前致谢。

viewData();
    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view, final int position, final long id) {
            alart=new AlertDialog.Builder(ViewData.this);
            alart.setTitle("Are you sure?");
            alart.setMessage("Are you sure want to clear  this data?");
            alart.setPositiveButton("YES", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {

                    boolean ans=mydb.deleteTitle(position);
                    Toast.makeText(getApplicationContext(),"->"+ans,Toast.LENGTH_SHORT).show();
                    adapter.notifyDataSetChanged();

                }
                
            });
            alart.setNegativeButton("NO", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.cancel();
                }
            });
            AlertDialog a = alart.create();
            a.show();
        }
    });

}

public void viewData() {
    Cursor res = mydb.getData();
    if (res.getCount() == 0) {
        Toast.makeText(ViewData.this, "No Data Found", Toast.LENGTH_SHORT);
    } else {
        while (res.moveToNext()) {
            arrayemail.add(res.getString(1) + "\n");
            arraypass.add(res.getString(2) + "\n");
        }
        adapter = new CustomAdapter(this, arrayemail, arraypass);
        listView.setAdapter(adapter);
    }

}

Answer 1

您正在从数据库中删除，但您没有从适配器中删除项目：

 boolean ans=mydb.deleteTitle(position); //this doesn't actually change the adapter, just the database.

所以

1. 从数据库中删除时从适配器中删除，然后在 onClick 方法中调用 notify changed
2. 从列表中删除一个项目后调用viewData()，也在onClick内，这将创建一个全新的适配器，再次从您的数据库中读取（这可能不是您应该采用的方法）