Android bitmap recycle necessary. Drawable. You need to maintain some object that is pointing to the bitmap, then it will not be recycled when you call setContentView () (or your equivalent) with a new bitmap. The recommended strategy depends on which version (s) of Android you are targeting. I am using famous lazylist. decodeFile(myFile2);第一个myBitmap会发生什么？它会被垃圾回收吗?还是我必须在加载另一个位图之前手动对其进行垃圾回收。myBitmap. When user click a button, it will set a new bitmap to the ImageView. 所以，对于图片的内存优化，是Android应用开发中比较重要的内容。 1) 要及时回收Bitmap的内存 Bitmap类有一个方法recycl_bitmap. 0 (API level 11), the pixel data is stored on the Dalvik heap along with the associated bitmap. I have about 40-50 thumbnails. Frequently we get image from server as byte stream, then we create Bitmap and assign it to ImageView object. I'm having serious issues with memory, and I'm looking forward to recycle bitmaps. When I don't need Bitmaps anymore, I usally recycle them by calling bitmap. decodeFile(myFile); Now, what will happen if I load another bitmap like myBitmap = BitmapFactory. isRecycled ()) { bitmap. On Android 2. Or more accurately, it seems to not be recreating the bitmap and remembering the recycle from last time. RESOLVED: In case its useful to anyone else, the solution to this problem as suggested by the accepted answer is to NOT do what I did in the code example above (don't recycle the bitmaps in the entryRemoved() call). RuntimeException: Canvas: trying to use a recycled bitmap android. recycle (). You should call recycle () when you are done using the bitmap. 0. 3 2. lang. The BitmapFun sample app included with this class shows you how to design your app to work efficiently across different versions of Android. Also prior to installing Lollipop, this worked OK (as long as I had bd = null). Icon)) imageView. DecodeResource( this. I am displaying the bitmaps in a grid view . (EDIT: no longer the case as of Android 3. I am having an issue with bitmap recycle. Set the bitm In addition to the steps described in Caching Bitmaps, there are specific things you can do to facilitate garbage collection and bitmap reuse. setBackground与setImageBitmap的图片来源，确保回收操作针对正确对象。 From another stackoverflow question, it seems that Android handles large bitmaps differently than other memory. If you call recycle () and later attempt to draw the bitmap, you will get the error: "Canvas: trying to use a recycled bitmap". To set the stage for this 假设我在一个位图对象中加载了一个图像，如下所示Bitmap myBitmap = BitmapFactory. It's good practice to set it to null afterwards, although this is somewhat redundant. 0 because memory are keep in native heap. recycle, which needs to be called during operation and on Activity destruction (note that onDestroy, even onStop might not be called). 7 I know that before API 10 of Android, it was important to call recycle() for Bitmap s that aren't used anymore, since the actual raw data is stored in the native memory. createBitmap Bitmap. And before recycling the bitmap it has to be ensured that it's not referenced by any view anymore - setting the references of the drawable / view to null. When I need to release memory, I can drop all ImageView references to null, letting th I've seen in a lot of samples, that developers call recycle() on bitmap, and then set it to null. 2 Bitmap has a recycle method, but do we have to invoke it explicitly if we don't need it any more? For example, an ImageView has a bitmap now. FYI - Bitmap#recycle () is only really necessary on Gingerbread and lower devices. I've got very critical problem. To answer your question, yes, setting bitmap to null after you have recycled it is a good idea, but it may also be redundant. Mono for Android documentation says exactly the same. Otherwise the exception will be thrown. The BitmapFun sample app… Nov 17, 2025 · In the world of Android development, handling bitmaps efficiently is critical to avoiding memory leaks, crashes, and poor app performance—especially on older devices. The requirements seem reasonable to me, but each one adds a dimension of difficulty, especially Bitmap. Running the bitmap recycle () onDestory () usually works if there aren't many images, but if you have a ton of images on the screen, you may have to handle them on-the-fly. Manage Memory on Android 2. In an effort to be memory-conservative, I'm attempting to use a temporary bitmap to load and another for the final image after transformation: . recycle () when the bitmap not use below Android 3. 3 (API level 10) and lower, using recycle () is recommended. It will recycle them unless you are using them elsewhere. If you're displaying large amounts of bitmap data in your app, you're likely to run into OutOfMemoryError errors. As of Android 3. Let's say I have loaded an image in a bitmap object like Bitmap myBitmap = BitmapFactory. Recycle () should be enough: Free the native object associated with this bitmap, and clear the reference to the pixel data. Bitmap. When one should take care of Bitmap memory management or recycling bitmap in android ? For example , there are few ways to create a bitmaps in android like following Bitmap. Bitmap@410a9720 which means recycle was called too early while a canvas was still using it. recycle ()什么时候使用 Android应用中，Bitmap的内存管理是个重要话题。 虽然Java的垃圾回收机制通常能处理Bitmap的释放，但在特定情况下，手动调用Bitmap的recycle方法可以避免潜在的内存泄漏和性能问题。 适时调用recycle可以减轻垃圾回收负担，特别是在长期运行的应用如launcher中。. decodeResource(getResources(), R. 1 I have created Bitmap like below, // create bitmap in the below line Bitmap myBitmap = BitmapFactory. However, as of API 11, Bitmap s are stored in the heap, so my question is: Is it still needed to call recycle() on Bitmap s if the API is large enough (at least 11)? The Bitmap. recycle () on the above Bitmap? 2> If yes then when should I call it? 15 I am writing a very memory intensive application for Android Honeycomb, and I've been very careful to recycle() unused Bitmap s wherever possible; indeed, this is necessary for the application to work at all, as Bitmap s are constantly being cycled in and out of memory. You should call recycle() to free the memory the bitmap is stored in once you are finished with it. Graphics. As google's said we must manually call Bitmap. in this below code after setting bitmap, i tried to do bitmap. finalBitmap. It also seems like there is a way to force Android to recycle the bitmaps to free up If the LRU Cache was going to evict an image to make room for another image, it sent a notification to all the listening Fragments and Activities. These listeners then marked their image as 'dirty', meaning they needed to be re-downloaded, and also then called recycle() on the bitmap. 1 Have a look at the android documentation about "How to draw bitmaps" Also the code example called bitmap fun. Jun 4, 2024 · In addition to the steps described in Caching Bitmaps , there are specific things you can do to facilitate garbage collection and bitmap reuse. recycle ()? Looking at the BitmapShader source, it clearly shows that the class doesn’t perform any type of releasing over the bitmap, yet it keeps a reference to avoid garbage collection since most of the implementation is in native code. googlelogo320x480); And I have set it to an ImageView. my questions are: 1> Do I need to explicitly call Bitmap. 3 The pixel memory of Bitmap was allocated on Natvie before, and it was not sure when it would be recycled. Recycle works. Consider using libraries like Glide or Picasso that automatically handle bitmap recycling and memory management. 3. On newer version of the OS bitmaps are stored on the heap and are garbage collected like other objects. BitmapFactory. My question is, is there a way to recycle this bitmap after I am done using it? While resuming, android doesn't decode the image again whether it is recycled or not, therefore, you are getting Canvas: trying to use a recycled bitmap. Is all of this code just equivalent to setting my Bitmap and ImageView to null in onDestroy, or is all of this extra work of tracking down underlying Bitamp objects and recycling them still valid and necessary? So I want to do recycle () the bitmaps for reclaiming the memory. recycle () method in Android is a crucial function used to free up the memory allocated for a Bitmap object. recycle () must always be called to free a Bitmap. These approaches can help GC to collect reference to ImageView properly Learn effective strategies for bitmap memory management in Android to optimize performance and reduce memory usage. If you use a ListView or a GridView the ImageView objects are getting recycled and the actual bitmap gets released to be cleaned up by the GC. recycle isn’t required to be called, as the garbage collector will clean up bitmaps on its own eventually (as long as there are no references). But the bitmap should be retrievable from the view. It helps prevent memory leaks and ensures optimal performance by freeing up unused bitmap memory when they are no longer needed. So in my present case I get a bitmap from S According to Android documentation Bitmap. recycle() However, there are a couple of situations in which I need to use the recycled Bitmap again, so usually I just l 2 In the documentation, titled "Managing Bitmap Memory" you can find the following statement: Caution: You should use recycle () only when you are sure that the bitmap is no longer being used. Ot Loading a single bitmap into your user interface (UI) is straightforward, however things get more complicated if you need to load a larger set of images at once. Having the bitmap instance in memory, it's possible to call recycle () on it to free memory immediatly. To put it simply, when you need a bitmap, you check a bitmap stack to see if there are any bitmaps available. 0 you need to recycle it, because the bitmap is stored in the native heap. For apps targeting devices running **Android 3. SetImageBitmap(bitmap); i saw this approach in several places, another one is the use of WeakReference to ImageView. This code has high chance raising: FATAL EXCEPTION: java. decodeResource( The Android docs clearly state that LRUCache is the way to go, but they do not mention the need to recycle bitmaps or how to do so. The code works but it has been brought to my attention that I should recycle this bitmap. Only Android 4. . Use the `recycle ()` method on the bitmap when it's no longer needed to free up memory resources. 0+) The real size of the Android开发中，合理使用recycle()释放Bitmap资源可减轻系统负担，避免"尝试使用已回收图片"异常。注意区分imageView. Resources, Resource. The way to get solve this issue is to reload the corresponding BitmapDrawable at onPause of your Activity so that android would not complain about the bitmap being recyced. There are a few instance where you would want to but considering most listview implementations it probably won't be necessary. Why is this necessary, doesn't the garbage collector take care of releasing the bitmap? Bitmap bit My app can load quite large images. using (var bitmap = Android. As fresco lib 's instructions, after decoding and pushing the bitmap into Ashmem, we call pinBitmap to prevent it from reclaiming by the system. So we could have a reference count for a Bitmap and check if need to recycle bitmap in ImageView's onDetachedFromWindow () when using ListView. Do we have to recycle the original bitmap before assign the new one? Each adds a dimension of difficulty, especially Bitmap. 3 (API level 10) and lower versions, the reserve pixel data of the bitmap is stored in local memory. Is it necessary to set a Bitmap to null after recycling it, so that its memory can be freed? In the following code: private static Bitmap bmpConcatHV() { Bitmap bmp = BitmapFactory. When no more hard references are kept of a bitmap object, the garbage collector will automatically collect it. 1, Bitmap is recycled automatically! I didn't call recycle() in my code! My project works fine in other OS versions( ~ 4. So, when you create the bitmap, store a reference to that bitmap somewhere, such as in an array, and keep that array around. But if you making extensive use of Bitmaps (speed of allocation may be greater than speed at which bitmap getting recycled) then you might want to recycle unused bitmaps ASAP. 0 (Honeycomb, API level 11)** or lower, bitmap management becomes even more challenging due to fundamental differences in how the Android framework handles bitmap memory What is bitmap pool Android? Bitmap pooling is a simple technique (though fairly complex to implement), that aims to reuse bitmaps instead of creating new ones every time. The recommended strategy depends on which version(s) of Android you are targeting. 3) with any resolutions. This problem doesn't happen if I use BitmapFactory to obtain the bitmap (unfortunately, I can't do that as I have to get this particular bitmap from an XML alias). Bitmaps in Android are created in native memory, not on the VM heap, so the actual bitmap object on the VM heap is very small as it doesn’t contain any actual bitmap data. when I down load the thumb image from the url I cached it to disk. drawable. In many cases (such as with components like ListView, GridView or LruCache class (also available… Provides detailed API reference for the Bitmap class in Android, including methods and properties to manage bitmap images effectively. decodeFile(myFile);现在，如果我加载另一个位图，会发生什么呢myBitmap = BitmapFactory. recycle Should I recycle a bitmap after assigning it to an ImageView? I always here talks of the importance of recycling bitmaps, but I am never quite sure when. As far as I can remember if a bitmap is placed in native memory has to do with what version of Android you're running, later versions of Android do not store them in native ram and on those you shouldn't need to call recycle. Devconsole's answer is great, but you can also store all bitmap objects in list like member of your class, and then recycle them in cycle when the onDestroy () method of activity (or some other release lifecycle method of component where you use bitmap) will be called. However, what my app is doing atm, is building a Gallery (yeah, the deprecated) with several bitmaps, and then, s Should we keep a reference of the bitmap and once the BitmapShader is no longer in use then to call bitmap. decodeFile( As of ICS the need to recycle isn't necessary. 0; so the method was helpful to assist the GC since it didn't otherwise have a record of that memory counted against its heap. 0 I am writing a small android application that uses an asyncTask to display an image from a web service. After the bitmap isn't used anymore, we recycle it b Once you have marked the Bitmap to be no longer needed by calling recycle () the bitmap is no longer useable, but probably has not been GC collected yet. 第一种方法--及时回收bitmap内存： 一般而言，回收bitmap内存可以用到以下代码 if (bitmap != null && !bitmap. Also, this question gets a little further on how Bitmap. Bitmapの処理を行なっているライブラリのコードを読むと、Bitmapのrecycle()メソッドが呼ばれていることに気づく。そこで、Bitmapのrecycle()の挙動について調べたので、以下にまとめる。 AndroidバージョンごとのBitmapのメモリ管理の違い 文章浏览阅读6k次，点赞4次，收藏8次。本文深入解析了Android中Bitmap在不同版本的回收机制，包括2. Now, if I understand correctly, the method Bitmap. The following sections describe how to optimize bitmap memory management for different Android versions. Recycling bitmaps is a crucial part of memory management in Android development. 3 and Lower On Android 2. 3 (API level 10) and lower, using recycle() is recommended. The issue you are having is that you are calling recycle() on a bitmap, which you are still trying to use. This approach seems to work pretty well overall. You also want to resize the original images to the screen size and cache them on disk and The recycle() method exists because Bitmap objects were not counted against the heap until Android 3. Before Android 2. where to call recycle () on bitmaps. according to Official documentation We need to manually call bitmap. 3之前的手动调用recycle方法，以及后续版本中通过BitmapFinalizer和NativeAllocationRegistry自动回收的原理。 In the Pre Android 3. So if the user jumps from Activty A to B and will return quickly, it's possible, that you have the same bitmap twice in memory, because the GC has not collected yet the first (recycled) bitmap. recycle () to recycle: On Android 2. graphics. 25 AFAIK on Android, it is recommended to reference Bitmap objects as WeakReferences in order to avoid memory leaks. It's particularly important in scenarios where performance and memory management are critical, such as in applications with heavy graphical content. 260bv, vpoaj, xvybk, tchk9, me9hbc, ziiw, gsub, 3dm2, ac2h5, vexl,