我正在创建一个应用程序,它从 Internet 检索图像并将它们显示在无限滚动的 ListView 中。问题是滚动一段时间后出现内存不足错误。谁能告诉我我在这里做错了什么?谢谢
主要 Activity :
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
context=this;
fetchPosts(lPost);
lv=(ListView) findViewById(R.id.listView1);
lv.setOnScrollListener(new InfiniteScrollListener(5) {
@Override
public void loadMore(int page, int totalItemsCount) {
fetchPosts(lPost);
}
});
cAdapter = new CustomAdapter(this, prgmNameList,prgmImages, prgmLikeNum, prgmCommentNum);
lv.setAdapter(cAdapter);
}
public void fetchImages(String imageName, int position) {
loadImage task = new loadImage(MainActivity.this, R.id.listView1, imageName, position );
task.setOnResultsListener(MainActivity.this);
task.execute("null");
}
public void fetchPosts(int lastPost){
LoadPosts lTask = new LoadPosts(MainActivity.this, lastPost);
lTask.setOnResultsListener(MainActivity.this);
lTask.execute("asd");
}
@Override
public void onResultsSucceeded(Bitmap image, int position) {
if(prgmImages.size() > position)
{
if(lPost==0)
prgmImages.set(position, image);
else
prgmImages.set(position+lPost-5, image);
}
cAdapter.notifyDataSetChanged();
}
@Override
public void onPostsSucceeded(JSONArray obj) throws JSONException {
//tView.setText(obj.toString());
lPost += obj.length();
for (int i = 0; i < obj.length(); i++) {
JSONObject object = obj.getJSONObject(i);
String postTitle = object.getString("post_title");
String imageName = object.getString("image_name");
String likeNum = object.getString("like_num");
String commentNum = object.getString("comment_num");
fetchImages(imageName, i);
prgmImages.add(null);
prgmNameList.add(postTitle);
prgmLikeNum.add(likeNum);
prgmCommentNum.add(commentNum);
}
}
自定义适配器:
public CustomAdapter(MainActivity mainActivity, ArrayList<String> prgmNameList, ArrayList<Bitmap> prgmImages, ArrayList<String> prgmLikeNum, ArrayList<String> prgmCommentNum) {
// TODO Auto-generated constructor stub
context=mainActivity;
activity=mainActivity;
inflater = ( LayoutInflater )context.
getSystemService(Context.LAYOUT_INFLATER_SERVICE);
result = prgmNameList;
imageId=prgmImages;
likeNum=prgmLikeNum;
commentNum=prgmCommentNum;
}
public class Holder
{
TextView tv;
ImageView img;
TextView likes;
TextView comments;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
holder=new Holder();
View rowView = convertView;
if(rowView == null)
{
rowView = inflater.inflate(R.layout.post_item, null);
}
holder.tv=(TextView) rowView.findViewById(R.id.postTitle);
holder.img=(ImageView) rowView.findViewById(R.id.postImage);
holder.likes=(TextView) rowView.findViewById(R.id.likeNum);
holder.comments=(TextView) rowView.findViewById(R.id.commentNum);
holder.tv.setText(result.get(position));
holder.img.setImageBitmap(imageId.get(position));
holder.likes.setText(likeNum.get(position));
holder.comments.setText(commentNum.get(position));
rowView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
// Toast.makeText(context, "You Clicked "+result[position], Toast.LENGTH_LONG).show();
}
});
return rowView;
}
最佳答案
这里有一些提高列表性能和摆脱 OOM 的要点
Android 应用程序的堆非常有限,因此您不应下载大量位图并将其存储在
List
中,它会引发 OOM。解决方案是在调用 getView() 时开始下载,所以不是
holder.img.setImageBitmap(imageId.get(position));
你应该有一个下载图像的请求.在 Android 中管理图像列表很困难,您必须注意:
- 调整位图大小
- 线程并发
- 缓存管理
为简单起见,我建议您使用这样的库:
例如,要使用 Glide 下载图像,您有:
Glide.with(mContext) .load(IMAGE_URL) .into(holder.img);
Glide/Picasso 将管理位图大小调整、并发和缓存:)
来自安卓文档
Your code might call findViewById() frequently during the scrolling of ListView, which can slow down performance.
更多信息 here .
所以你必须将这些行移动到 if(rowView == null)
条件
holder.tv=(TextView) rowView.findViewById(R.id.postTitle);
holder.img=(ImageView) rowView.findViewById(R.id.postImage);
holder.likes=(TextView) rowView.findViewById(R.id.likeNum);
holder.comments=(TextView) rowView.findViewById(R.id.commentNum);
- 您不应该在每次调用
getView()
时都创建一个新的 Holder!
这是 getView()
的正确实现
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
Holder holder;
// Check if the item's view is recycled
if(convertView == null)
{
// The item's view doesn't exist
// Create the item's view
LayoutInflater inflater = ((Activity) mContext).getLayoutInflater();
convertView = inflater.inflate(R.layout.post_item, null);
holder = new Holder(); // Create the holder
holder.tv=(TextView) rowView.findViewById(R.id.postTitle);
holder.img=(ImageView) rowView.findViewById(R.id.postImage);
holder.likes=(TextView) rowView.findViewById(R.id.likeNum);
holder.comments=(TextView) rowView.findViewById(R.id.commentNum);
// Store the holder with the view.
convertView.setTag(holder);
}
else
{
// The item's view already exist
// Retrieve the older
holder = (Holder) convertView.getTag();
}
holder.tv.setText(result.get(position));
holder.img.setImageBitmap(imageId.get(position));
Glide.with(mContext)
.load(imageUrls.get(position))
.into(holder.img)
holder.likes.setText(likeNum.get(position));
holder.comments.setText(commentNum.get(position));
convertView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO impl
}
});
return convertView;
}
更多信息 here .
希望它的帮助:)
关于android - 使用无限滚动android listview时出现内存不足错误,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/33064587/