/* * Copyright (c) 2003, 2008, Oracle and/or its affiliates. All rights reserved. * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. * * * * * * * * * * * * * * * * * * * * */ package java.lang.management; /** * The management interface for the garbage collection of * the Java virtual machine. Garbage collection is the process * that the Java virtual machine uses to find and reclaim unreachable * objects to free up memory space. A garbage collector is one type of * {@link MemoryManagerMXBean memory manager}. * * <p> A Java virtual machine may have one or more instances of * the implementation class of this interface. * An instance implementing this interface is * an <a href="ManagementFactory.html#MXBean">MXBean</a> * that can be obtained by calling * the {@link ManagementFactory#getGarbageCollectorMXBeans} method or * from the {@link ManagementFactory#getPlatformMBeanServer * platform <tt>MBeanServer</tt>} method. * * <p>The <tt>ObjectName</tt> for uniquely identifying the MXBean for * a garbage collector within an MBeanServer is: * <blockquote> * {@link ManagementFactory#GARBAGE_COLLECTOR_MXBEAN_DOMAIN_TYPE * <tt>java.lang:type=GarbageCollector</tt>}<tt>,name=</tt><i>collector's name</i> * </blockquote> * * It can be obtained by calling the * {@link PlatformManagedObject#getObjectName} method. * * A platform usually includes additional platform-dependent information * specific to a garbage collection algorithm for monitoring. * * @see ManagementFactory#getPlatformMXBeans(Class) * @see MemoryMXBean * * @see <a href="../../../javax/management/package-summary.html"> * JMX Specification.</a> * @see <a href="package-summary.html#examples"> * Ways to Access MXBeans</a> * * @author Mandy Chung * @since 1.5 */ public interface GarbageCollectorMXBean extends MemoryManagerMXBean { /** * Returns the total number of collections that have occurred. * This method returns <tt>-1</tt> if the collection count is undefined for * this collector. * * @return the total number of collections that have occurred. */ public long getCollectionCount(); /** * Returns the approximate accumulated collection elapsed time * in milliseconds. This method returns <tt>-1</tt> if the collection * elapsed time is undefined for this collector. * <p> * The Java virtual machine implementation may use a high resolution * timer to measure the elapsed time. This method may return the * same value even if the collection count has been incremented * if the collection elapsed time is very short. * * @return the approximate accumulated collection elapsed time * in milliseconds. */ public long getCollectionTime(); }