Android内存泄漏分析及实践（二）

通过《Android内存泄漏分析及实践（一）》我们得到结论：可以通过查询ReferenceQueue是否包含WeakReference实例，判断弱引用指向的对象 o是否被系统回收。所以根据这个理论我们可以写一个简单的内存泄露分析工具。

import java.lang.ref.Reference;import java.lang.ref.ReferenceQueue;import java.lang.ref.WeakReference;public class CheckWhenAnObjectIsNoLongerReferenced {    private static Object object;    public static void main(String[] args) {        object = new Object();        // Reference queue, to which registered reference objects are appended        // by the        // garbage collector after the appropriate reachability changes are        // detected.        ReferenceQueue<Object> rq = new ReferenceQueue<Object>();        // Create a new weak reference that refers to the given object and is        // registered with this queue.        WeakReference<Object> wr = new WeakReference<Object>(object, rq);        // start a new thread that will remove all references of object        new Thread(runnable).start();        // wait for all the references to the object to be removed        try {        Reference<?> r = null;            while ((r = rq.remove()) != null) {                if (r == wr) {                    System.out.println("Object is no longer referenced.");                    break;                }            }        } catch (InterruptedException e) {            e.printStackTrace();        }    }    private static Runnable runnable = new Runnable() {        @Override        public void run() {            try {                Thread.sleep(1000);                System.out.println("Setting object to null");                object = null;                System.out.println("Running Garbage Collection...");                Runtime.getRuntime().gc(); // run GC to collect the object            } catch (Exception e) {                e.printStackTrace();            }        }    };}

Output:
Setting object to null
Running Garbage Collection…
Object is no longer referenced.