android - 自定义适配器不刷新 android 中 onclicklistener 的 ListView

Question

我使用 onclicklistener 删除了数据库条目，但它没有刷新 ListView 。我怎样才能刷新这个 ListView ？

这是 ListView 的主类:

public class AFragment extends Fragment implements OnItemClickListener {

    protected static final String file_name ="user";
    ListView list;
    Database entry;
    View v;
    String values[];
    MySimpleArrayAdapter adapter;
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // Inflate the layout for this fragment

        SharedPreferences settings = getActivity().getSharedPreferences(file_name, 0);
        String name =  settings.getString("name", null);


        entry = new Database(getActivity());
        entry.open();
        values=entry.planlist(name);
        entry.close();
        if(values.length>0){
            v = inflater.inflate(R.layout.activity_afragment, container,false);
            adapter = new MySimpleArrayAdapter(getActivity(), values);
            list=(ListView)v.findViewById(R.id.list);

            list.setAdapter(adapter);
            adapter.notifyDataSetChanged();
            list.setOnItemClickListener(this);


        }else{
            v = inflater.inflate(R.layout.activity_my_tabs_listener, container,false);
        }
//      Toast.makeText(getActivity(),String.valueOf(values.length), Toast.LENGTH_LONG).show();
        return v;
    }


    @Override
    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
        // TODO Auto-generated method stub
        Intent i = new Intent(getActivity(),Details.class);
        i.putExtra("sub", values[arg2]);
        startActivity(i);
        Toast.makeText(getActivity(), "clicked", Toast.LENGTH_SHORT).show();
    }

}


Here i use onclicklistener to delete data from database but it is not refreshing:

public class MySimpleArrayAdapter extends ArrayAdapter<String>  {

      private final Context context;
      private final String[] values;
      public Business aFragment = new Business();
      int mypos =0;
      ViewHolder holder;
      View row;
      public MySimpleArrayAdapter(Context context, String[] values) {
        super(context,R.layout.activity_my_simple_array_adapter, values);
        this.context = context;
        this.values = values;
      }


      @Override
      public View getView(int position, View convertView, ViewGroup parent) {

        mypos = position;
        row = convertView;
        holder = new ViewHolder();
        if (row == null) {
            LayoutInflater inflater = ((Activity) context).getLayoutInflater();
            row = inflater.inflate(R.layout.activity_my_simple_array_adapter, parent, false);

            TextView textView = (TextView) row.findViewById(R.id.text);
            Button btn = (Button) row.findViewById(R.id.button1);
            holder.tv = textView;
            holder.btn = btn;
            row.setTag(holder);
        }else{
            holder = (ViewHolder)row.getTag();
        }
        holder.tv.setText(values[position]);
        final int id = position;
        holder.btn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                Database entry = new Database(context);
                entry.open();
                entry.delete(values[id]);
                entry.close();
//              Toast.makeText(getContext(), String.valueOf(id), Toast.LENGTH_LONG).show();
            }
        });

        return row;
      }

    static class ViewHolder{

        TextView tv;
        Button btn;

    }
} 

Answer 1

正如 anil 所说，你应该把 notifyDataSetChanged();在 onClickListener 里面这基本上告诉适配器再次呈现列表，并将为列表中的每个可见项目再次调用 getView()，如果您的代码崩溃，您应该检查两件事:首先 - 调试程序并检查新数据是否符合您的要求，在您的情况下，检查条目是否已正确删除。

其次 - 调试 getView 方法，逐步执行每个调用并查看导致崩溃的原因。

在你的情况下，问题是你只是在更新数据库，但实际上你的 ListView 数据是从 values[] 数组中获取的，它在你删除数据库条目后没有更新，你应该创建一个函数来更新它.