从ViewPager返回活动结果

public interface OnResultListener {
    void onResult(int resultCode, Intent data);
}

public class FragmentA extends Fragment {
    private OnResultListener mListener;

    // 在需要返回结果的地方调用接口方法
    private void returnResult(int resultCode, Intent data) {
        if (mListener != null) {
            mListener.onResult(resultCode, data);
        }
    }

    // 在片段与活动关联时，将活动设置为接口的实例
    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof OnResultListener) {
            mListener = (OnResultListener) context;
        } else {
            throw new RuntimeException(context.toString()
                    + " must implement OnResultListener");
        }
    }

    // 在片段与活动解除关联时，将接口实例置空
    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }
}

public class MainActivity extends AppCompatActivity implements OnResultListener {
    // ...

    @Override
    public void onResult(int resultCode, Intent data) {
        // 处理从片段传递过来的结果
    }
}

public class ViewPagerAdapter extends FragmentPagerAdapter {
    private MainActivity mActivity;

    public ViewPagerAdapter(MainActivity activity, FragmentManager fm) {
        super(fm);
        mActivity = activity;
    }

    @Override
    public Fragment getItem(int position) {
        // 创建片段实例，并将活动实例传递给片段
        Fragment fragment = new FragmentA();
        Bundle args = new Bundle();
        args.putSerializable("activity", mActivity);
        fragment.setArguments(args);
        return fragment;
    }

    // ...
}