RecyclerView 适配器的生命周期是什么? [英] What is lifecycle for RecyclerView adapter?

问题描述

我在适配器中请求演示者提供图像:

I'm requesting images from presenter in adapter:

  @Override
  public void onBindViewHolder(SiteAdapter.ViewHolder holder, int position)
  {
    Site site = sites.get(position);
    holder.siteName.setText(site.getName());
    requestHolderLogo(holder, site.getLinks().getLogoUrl());
  }

  private void requestHolderLogo(final ViewHolder holder, final String logoUrl)
  {
    compositeSubscription.add(
      presenter.bitmap(logoUrl)
        .subscribe(
          bitmap -> {
            holder.siteLogo.setImageBitmap(bitmap);
            holder.siteLogo.setVisibility(View.VISIBLE);
          },
          error -> {
            holder.siteName.setVisibility(View.VISIBLE);
          })
    );
  }

当 ViewHolder 被重新使用时，我应该取消订阅.很简单.

I should unsubscribe when ViewHolder is re-used. It is easy.

但是当视图被销毁时如何停止所有订阅?我也应该取消演示者引用以避免内存泄漏

But how stop all subscription when view is destroyed? I should also probably nullify presenter reference to avoid memory leak

推荐答案

我认为最好的方法是:

1. 在 SiteAdapter.ViewHolder
中保留一个 subscription 引用
2. unsubscribe onBindViewHolder 中的 subscription 对象(当 ViewHolder 被重用时调用)
3. 在您的适配器
中保留CompositeSubscription对象
4. 使用Adapter的onDetachedFromRecyclerView方法来取消订阅compositeSubscription

1. Keep a subscription reference in the SiteAdapter.ViewHolder
2. unsubscribe the subscription object in onBindViewHolder (it's called when the ViewHolder is reused)
3. Keep the CompositeSubscription object in your adapter
4. Use the onDetachedFromRecyclerView method of your Adapter to unsubscribe the compositeSubscription

像这样:

public class SiteAdapter extends RecyclerView.Adapter<SiteAdapter.ViewHolder> {

    private CompositeSubscription compositeSubscription = new CompositeSubscription();

    // other needed SiteAdapter methods

    @Override
    public void onBindViewHolder(SiteAdapter.ViewHolder holder, int position) {
        if (holder.subscription != null && !holder.subscription.isUnsubscribed()) {
            compositeSubscription.remove(holder.subscription);
            // this will unsubscribe the subscription as well
        }
        Site site = sites.get(position);
        holder.siteName.setText(site.getName());
        requestHolderLogo(holder, site.getLinks().getLogoUrl());
    }

    private void requestHolderLogo(final SiteAdapter.ViewHolder holder, final String logoUrl) {
        holder.subscription = presenter.bitmap(logoUrl)
                .subscribe(
                        bitmap -> {
                            holder.siteLogo.setImageBitmap(bitmap);
                            holder.siteLogo.setVisibility(View.VISIBLE);
                        },
                        error -> {
                            holder.siteName.setVisibility(View.VISIBLE);
                        });
        compositeSubscription.add(holder.subscription);
    }

    @Override
    public void onDetachedFromRecyclerView(RecyclerView recyclerView) {
        compositeSubscription.unsubscribe();
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {

        public Subscription subscription;

        // some holder-related stuff

        public ViewHolder(View itemView) {
            super(itemView);
            // init holder
        }
    }
}

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