- @param position 下标
- @param packageName 要替换的文本名
*/
public void updateItem(int position, String packageName) {
if (position >= 0 && position < data.size()) {
data.get(position).setPackageName(packageName);
}
notifyDataSetChanged();
}
踩坑
而我们要做的是一个下载列表,在下载的callback里面我们要去更新列表的progressBar还有Button的文本:
Activity中获取到下载的callback:
@Override
public void onProgress(long finished, long total, int progress) {
XLog.e(mInfoBean.getDownLoadUrl() + “-----------||||||” + progress);
String downloadPerSize = Kits.File.getDownloadPerSize(finished, total);
mInfoBean.setDownLoadStatus(STATUS_DOWNLOADING);
mInfoBean.setDownloadPerSize(downloadPerSize);
mInfoBean.setProgress(progress);
if (isCurrentListViewItemVisible(mPosition)) {
mTestDownLoadAdapter.setProgress(progress, mPosition, downloadPerSize);
}
}
适配器中暴露的用于更新progressBar进度的方法
/**
- 暴露用于修改进度值的方法
- @param progress
- @param position
- @param progressStr
*/
public void setProgress(int progress, int position, String progressStr) {
data.get(position).setProgress(progress);
data.get(position).setDownloadPerSize(progressStr);
notifyItemChanged(position);
}
适配器的onBindViewHolder()中处理数据结果
@Override
public void onBindViewHolder(final TestDownLoadHolder holder, final int position) {
final AppInfoBean appInfoBean = data.get(position);
if (appInfoBean != null) {
ILFactory.getLoader().loadNet(holder.mIvDownPic, appInfoBean.getDownLoadPic(), ImgOptions.getDefImaOptions());
holder.mPbDownProgress.setProgress(appInfoBean.getProgress());
holder.mBtDownLoad.setText(appInfoBean.getDownloadPerSize());
holder.mBtDownLoad.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (getRecItemClick() != null) {
getRecItemClick().onItemClick(position, appInfoBean, 0, holder);
}
}
});
}
}
这里我们使用的是notifyItemChanged局部刷新而不是notifyDataSetChanged。讲道理我们到了这一步就已经可以满足需求了,然而…事实不讲道理:
[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-D02S7a5j-1646116102674)(https://user-gold-cdn.xitu.io/2017/10/27/72395e18c6486bb49278862724e630b4?imageView2/0/w/1280/h/960/ignore-error/1)]
一闪一闪亮晶晶
额…原谅demo画得太丑了。这里我们可以发现…为毛我的图片…一闪一闪的,亮瞎我的狗眼了。
至于为什么会闪动?
猜测:
- ImageView的宽高问题,重新计算导致了闪动
- 更新到了ImageView,然后glide又重新加载了一次图片。
- 刷新到了ImageView,这个item渲染了一次。
解疑:
- 采用了写死宽高的方法,但是!页面还是会闪动…gif就不传了,录制好麻烦。猜测1已经否决了。
ILFactory.getLoader().loadNet(holder.mIvDownPic, appInfoBean.getDownLoadPic(), ImgOptions.getDefImaOptions());
android:src="@mipmap/ic_launcher"
- 重新理下,我们需要更新的是Button和progressBar,其实ImageView我们是不需要额外去更新的。
那我们的问题就聚焦在如何只更新一部分控件,其他控件不动
解决
至于怎么解决呢…扒源码:
/**
- Notify any registered observers that the item at
position
has changed. - Equivalent to calling
notifyItemChanged(position, null);
. -
This is an item change event, not a structural change event. It indicates that any
- reflection of the data at
position
is out of date and should be updated. - The item at
position
retains the same identity. - @param position Position of the item that has changed
- @see #notifyItemRangeChanged(int, int)
*/
public final void notifyItemChanged(int position) {
mObservable.notifyItemRangeChanged(position, 1);
}
/**
- Notify any registered observers that the item at
position
has changed with an - optional payload object.
-
This is an item change event, not a structural change event. It indicates that any
- reflection of the data at
position
is out of date and should be updated. - The item at
position
retains the same identity. -
- Client can optionally pass a payload for partial change. These payloads will be merged
- and may be passed to adapter’s {@link #onBindViewHolder(ViewHolder, int, List)} if the
- item is already represented by a ViewHolder and it will be rebound to the same
- ViewHolder. A notifyItemRangeChanged() with null payload will clear all existing
- payloads on that item and prevent future payload until
- {@link #onBindViewHolder(ViewHolder, int, List)} is called. Adapter should not assume
- that the payload will always be passed to onBindViewHolder(), e.g. when the view is not
- attached, the payload will be simply dropped.
- @param position Position of the item that has changed
- @param payload Optional parameter, use null to identify a “full” update
- @see #notifyItemRangeChanged(int, int)
*/
public final void notifyItemChanged(int position, Object payload) {
mObservable.notifyItemRangeChanged(position, 1, payload);
}
在这里我们看到一句话:
@param payload Optional parameter, use null to identify a “full” update
传入“null”就是更新全部!那我们调用的时候是传入什么呢!看下:
public final void notifyItemChanged(int position) {
mObservable.notifyItemRangeChanged(position, 1);
}
继而调用:
public void notifyItemRangeChanged(int positionStart, int itemCount) {
notifyItemRangeChanged(positionStart, itemCount, null);
}
继而调用:
public void notifyItemRangeChanged(int positionStart, int itemCount, Object payload) {
// since onItemRangeChanged() is implemented by the app, it could do anything, including
// removing itself from {@link mObservers} - and that could cause problems if
// an iterator is used on the ArrayList {@link mObservers}.
// to avoid such problems, just march thru the list in the reverse order.
for (int i = mObservers.size() - 1; i >= 0; i–) {
mObservers.get(i).onItemRangeChanged(positionStart, itemCount, payload);
}
}
[捂脸] 一个大写的null…
OK,那我们修改下我们的调用方法:
/**
- 暴露用于修改进度值的方法
- @param progress
- @param position
- @param progressStr
*/
public void setProgress(int progress, int position, String progressStr) {
data.get(position).setProgress(progress);
data.get(position).setDownloadPerSize(progressStr);
notifyItemChanged(position, 1);
}
/**
- 暴露用于修改按钮文字值的方法
- @param position
- @param buttonStr
*/
public void setButtonStatus(int position, String buttonStr) {
data.get(position).setDownloadPerSize(buttonStr);
notifyItemChanged(position, 1);
}
这里我们传入了一个 “1”,这个1是随意传入的,其他值也可以。
继而我们需要重写onBindViewHolder方法如下:
@Override
public void onBindViewHolder(TestDownLoadHolder holder, int position, List payloads) {
XLog.e("--------------------------has payloads");
if (payloads.isEmpty()) {
XLog.e("--------------------------no payloads");
onBindViewHolder(holder, position);
} else {
XLog.e("--------------------------false payloads");
final AppInfoBean appInfoBean = data.get(position);
if (appInfoBean != null) {
holder.mPbDownProgress.setProgress(appInfoBean.getProgress());
holder.mBtDownLoad.setText(appInfoBean.getDownloadPerSize());
}
}
}
@Override
public void onBindViewHolder(final TestDownLoadHolder holder, final int position) {
final AppInfoBean appInfoBean = data.get(position);
if (appInfoBean != null) {
ILFactory.getLoader().loadNet(holder.mIvDownPic, appInfoBean.getDownLoadPic(), ImgOptions.getDefImaOptions());
holder.mPbDownProgress.setProgress(appInfoBean.getProgress());
holder.mBtDownLoad.setText(appInfoBean.getDownloadPerSize());
holder.mBtDownLoad.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (getRecItemClick() != null) {
getRecItemClick().onItemClick(position, appInfoBean, 0, holder);
}
}
});
}
}
getDownloadPerSize());
holder.mBtDownLoad.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (getRecItemClick() != null) {
getRecItemClick().onItemClick(position, appInfoBean, 0, holder);
}
}
});
}
}