如何在 Fragment 和适配器之间创建接口? [英] How to create interface between Fragment and adapter?

问题描述

我有带有 ListView 的片段，比如 MyListFragment 和自定义的 CursorAdapter.我正在此适配器中为列表行中的按钮设置 onClickListener.

I have fragment with ListView, say MyListFragment, and custom CursorAdapter. I'm setting onClickListener in this adapter for the button in the list row.

public class MyListAdapter extends CursorAdapter {

    public interface AdapterInterface {
        public void buttonPressed();
    }

    ...

    @Override
    public void bindView(final View view, final Context context, final Cursor cursor) {
        ViewHolder holder = (ViewHolder) view.getTag();

        ...

        holder.button.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                // some action
                // need to notify MyListFragment
            }
        });
    }
}

public MyListFragment extends Fragment implements AdapterInterface {

    @Override
    public void buttonPressed() {
        // some action
    }
}

我需要在按下按钮时通知片段.如何调用这个接口?

I need to notify fragment when the button is pressed. How to invoke this interface?

请帮忙.

推荐答案

创建一个新的构造函数和一个实例变量:

Make a new constructor and an instance variable:

AdapterInterface buttonListener;

public MyListAdapter (Context context, Cursor c, int flags, AdapterInterface buttonListener)
{
  super(context,c,flags);
  this.buttonListener = buttonListener;
}

创建适配器时，实例变量将被赋予适当的引用以保持.

When the Adapter is made, the instance variable will be given the proper reference to hold.

通过点击调用片段:

public void onClick(View v) {
   buttonListener.buttonPressed();
}

在制作 Adapter 时，您还必须将 Fragment 传递给 Adapter.例如

When making the Adapter, you will have to also pass your Fragment off to the Adapter. For example

MyListAdapter adapter = new MyListAdapter (getActivity(), myCursor, myFlags, this);

因为 this 将引用您的 Fragment，它现在是一个 AdapterInterface.

since this will refer to your Fragment, which is now an AdapterInterface.

请记住，在 Fragment 的方向发生变化时，它很可能会被重新创建.如果您的 Adapter 没有重新创建，它可能会保留对不存在对象的引用，从而导致错误.

Keep in mind that on orientation of the Fragment changes, it will most likely be recreated. If your Adapter isn't recreated, it can potentially keep a reference to a nonexistent object, causing errors.

这篇关于如何在 Fragment 和适配器之间创建接口?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！