java 如何在android中释放对象？
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How to free object in android?
提问by barssala
Possible Duplicate:
Java garbage collection
可能的重复：
Java 垃圾收集
I know that we have to free object in C, C++ after processing finish to get back the memory. However, I don't know how to free object in java and android. Is that enough for just assign nullto the object?
我知道我们必须在处理完成后释放 C、C++ 中的对象以取回内存。但是，我不知道如何在 java 和 android 中释放对象。仅分配null给对象就足够了吗？
回答by Matt Clark
In Java it is un-necessary to free objects.
在 Java 中，没有必要释放对象。
Java has a built in Garbage Collector which runs when ever it needs to and clear out all resources that are no longer in use in order to free memory. A java developer may make a call to the java runtime to run the Garbage Collecter using System.gc();however this is just a suggestion to the runtime and may not always result in it being run.
Java 有一个内置的垃圾收集器，它在需要时运行并清除所有不再使用的资源以释放内存。java 开发人员可以调用 java 运行时来运行垃圾收集器，System.gc();但这只是对运行时的建议，可能并不总是导致它运行。
In cases where you are using readers and images, be sure to call .recycle()and .close()where applicable.
如果您使用阅读器和图像，请务必致电.recycle()并.close()在适用的情况下致电。
回答by Matt Clark
A simple java object especially (E.g. model objects) can be freed by garbage collector IFother objects has no reference to it.
一个简单的java对象（例如模型对象）可以被垃圾收集器释放，如果其他对象没有引用它。
If I were you, don't trust too much that garbage collector because there are some objects that you must free, one of them is the Bitmapobjects
如果我是你，不要太相信垃圾收集器，因为有些对象你必须释放，其中之一就是Bitmap对象
Bitmaps eat more RAM in your android app.
Bitmap在你的安卓应用中吃更多的内存。
Bitmap b = createLargeBitmap();
Bitmap b2 = b;
If you remove all references to that object and let garbage collector kill it
如果您删除对该对象的所有引用并让垃圾收集器杀死它
b = null;
b2 = null;
you might get a memory leak or OutOfMemoryerror.
您可能会遇到内存泄漏或OutOfMemory错误。
So you need to call recycle()to fully freed the bitmap.
所以你需要调用recycle()来完全释放位图。
b.recycle();
b = null;
b2 = null;
// Sorry for my wrong grammar :)
// 抱歉我的语法错误:)
回答by Mudassir Hasan
Memory deallocation is automatically done by Java garbage collector . You can't force garbage collector to free memory through your code.
内存释放由 Java 垃圾收集器自动完成。你不能强制垃圾收集器通过你的代码释放内存。
Calling System.gc()doesnot guarantee garbage collector to RUN and FREEmemory , final decision is taken by Java runtime.
调用System.gc()并不能保证垃圾收集器运行并释放内存，最终决定由 Java 运行时做出。
回答by wtsang02
回答by gerrytan
Android (which uses Java language) is a garbage-collected environment, meaning the virtual machine will automatically remove objects which no longer have any references.
Android（使用 Java 语言）是一个垃圾收集环境，这意味着虚拟机将自动删除不再有任何引用的对象。
Hence the question you should be asking is: how do you ensure your program does not use too much memory. This is normally achieved by ensuring you don't put too many objects in your in-memory data structure, persist your information into file system etc.
因此，您应该问的问题是：您如何确保您的程序不会使用太多内存。这通常是通过确保您不会在内存数据结构中放入太多对象、不会将您的信息保存到文件系统等来实现的。
