Module jdk.management
Package com.sun.management

Class GcInfo

java.lang.Object
com.sun.management.GcInfo
All Implemented Interfaces:
CompositeData, CompositeDataView
public class GcInfo extends Object implements CompositeData, CompositeDataView
Garbage collection information. It contains the following information for one garbage collection as well as GC-specific attributes:
  • Start time
  • End time
  • Duration
  • Memory usage before the collection starts
  • Memory usage after the collection ends

GcInfo is a CompositeData The GC-specific attributes can be obtained via the CompositeData interface. This is a historical relic, and other classes should not copy this pattern. Use CompositeDataView instead.

MXBean Mapping

GcInfo is mapped to a CompositeData with attributes as specified in the from method.
Since:
1.5

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    containsKey(String key)
    Returns true if and only if this CompositeData instance contains an item whose name is key.
    boolean
    containsValue(Object value)
    Returns true if and only if this CompositeData instance contains an item whose value is value.
    boolean
    equals(Object obj)
    Indicates whether some other object is "equal to" this one.
    static GcInfo
    from(CompositeData cd)
    Returns a GcInfo object represented by the given CompositeData.
    Object
    get(String key)
    Returns the value of the item whose name is key.
    Object[]
    getAll(String[] keys)
    Returns an array of the values of the items whose names are specified by keys, in the same order as keys.
    CompositeType
    getCompositeType()
    Returns the composite type of this composite data instance.
    long
    getDuration()
    Returns the elapsed time of this GC in milliseconds.
    long
    getEndTime()
    Returns the end time of this GC in milliseconds since the Java virtual machine was started.
    long
    getId()
    Returns the identifier of this garbage collection which is the number of collections that this collector has done.
    Map<String,MemoryUsage>
    getMemoryUsageAfterGc()
    Returns the memory usage of all memory pools at the end of this GC.
    Map<String,MemoryUsage>
    getMemoryUsageBeforeGc()
    Returns the memory usage of all memory pools at the beginning of this GC.
    long
    getStartTime()
    Returns the start time of this GC in milliseconds since the Java virtual machine was started.
    int
    hashCode()
    Returns a hash code value for the object.
    CompositeData
    toCompositeData(CompositeType ct)
    Return the CompositeData representation of this GcInfo, including any GC-specific attributes.
    String
    toString()
    Returns a string representation of the object.
    Collection<?>
    values()
    Returns an unmodifiable Collection view of the item values contained in this CompositeData instance.

    Methods declared in class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Method Details

    • getId

      public long getId()
      Returns the identifier of this garbage collection which is the number of collections that this collector has done.
      Returns:
      the identifier of this garbage collection which is the number of collections that this collector has done.

    • getStartTime

      public long getStartTime()
      Returns the start time of this GC in milliseconds since the Java virtual machine was started.
      Returns:
      the start time of this GC.

    • getEndTime

      public long getEndTime()
      Returns the end time of this GC in milliseconds since the Java virtual machine was started.
      Returns:
      the end time of this GC.

    • getDuration

      public long getDuration()
      Returns the elapsed time of this GC in milliseconds.
      Returns:
      the elapsed time of this GC in milliseconds.

    • getMemoryUsageBeforeGc

      public Map<String,MemoryUsage> getMemoryUsageBeforeGc()
      Returns the memory usage of all memory pools at the beginning of this GC. This method returns a Map of the name of a memory pool to the memory usage of the corresponding memory pool before GC starts.
      Returns:
      a Map of memory pool names to the memory usage of a memory pool before GC starts.

    • getMemoryUsageAfterGc

      public Map<String,MemoryUsage> getMemoryUsageAfterGc()
      Returns the memory usage of all memory pools at the end of this GC. This method returns a Map of the name of a memory pool to the memory usage of the corresponding memory pool when GC finishes.
      Returns:
      a Map of memory pool names to the memory usage of a memory pool when GC finishes.

    • from

      public static GcInfo from(CompositeData cd)
      Returns a GcInfo object represented by the given CompositeData. The given CompositeData must contain all the following attributes:
      description
      Attribute Name Type
      index java.lang.Long
      startTime java.lang.Long
      endTime java.lang.Long
      memoryUsageBeforeGc javax.management.openmbean.TabularData
      memoryUsageAfterGc javax.management.openmbean.TabularData
      Returns:
      a GcInfo object represented by cd if cd is not null; null otherwise.
      Throws:
      IllegalArgumentException - if cd does not represent a GcInfo object with the attributes described above.

    • containsKey

      public boolean containsKey(String key)
      Description copied from interface: CompositeData
      Returns true if and only if this CompositeData instance contains an item whose name is key. If key is a null or empty String, this method simply returns false.
      Specified by:
      containsKey in interface CompositeData
      Parameters:
      key - the key to be tested.
      Returns:
      true if this CompositeData contains the key.

    • containsValue

      public boolean containsValue(Object value)
      Description copied from interface: CompositeData
      Returns true if and only if this CompositeData instance contains an item whose value is value.
      Specified by:
      containsValue in interface CompositeData
      Parameters:
      value - the value to be tested.
      Returns:
      true if this CompositeData contains the value.

    • equals

      public boolean equals(Object obj)
      Description copied from class: Object
      Indicates whether some other object is "equal to" this one.

      The equals method implements an equivalence relation on non-null object references:

      • It is reflexive: for any non-null reference value x, x.equals(x) should return true.
      • It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
      • It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
      • It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
      • For any non-null reference value x, x.equals(null) should return false.

      An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes.

      Specified by:
      equals in interface CompositeData
      Overrides:
      equals in class Object
      Parameters:
      obj - the reference object with which to compare.
      Returns:
      true if this object is the same as the obj argument; false otherwise.
      See Also:

    • get

      public Object get(String key)
      Description copied from interface: CompositeData
      Returns the value of the item whose name is key.
      Specified by:
      get in interface CompositeData
      Parameters:
      key - the name of the item.
      Returns:
      the value associated with this key.

    • getAll

      public Object[] getAll(String[] keys)
      Description copied from interface: CompositeData
      Returns an array of the values of the items whose names are specified by keys, in the same order as keys.
      Specified by:
      getAll in interface CompositeData
      Parameters:
      keys - the names of the items.
      Returns:
      the values corresponding to the keys.

    • getCompositeType

      public CompositeType getCompositeType()
      Description copied from interface: CompositeData
      Returns the composite type of this composite data instance.
      Specified by:
      getCompositeType in interface CompositeData
      Returns:
      the type of this CompositeData.

    • hashCode

      public int hashCode()
      Description copied from class: Object
      Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap.

      The general contract of hashCode is:

      • Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
      • If two objects are equal according to the equals method, then calling the hashCode method on each of the two objects must produce the same integer result.
      • It is not required that if two objects are unequal according to the equals method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.
      Specified by:
      hashCode in interface CompositeData
      Overrides:
      hashCode in class Object
      Returns:
      a hash code value for this object.
      See Also:

    • toString

      public String toString()
      Description copied from class: Object
      Returns a string representation of the object.
      Specified by:
      toString in interface CompositeData
      Overrides:
      toString in class Object
      Returns:
      a string representation of the object.

    • values

      public Collection<?> values()
      Description copied from interface: CompositeData
      Returns an unmodifiable Collection view of the item values contained in this CompositeData instance. The returned collection's iterator will return the values in the ascending lexicographic order of the corresponding item names.
      Specified by:
      values in interface CompositeData
      Returns:
      the values.

    • toCompositeData

      public CompositeData toCompositeData(CompositeType ct)
      Return the CompositeData representation of this GcInfo, including any GC-specific attributes. The returned value will have at least all the attributes described in the from method, plus optionally other attributes.
      Specified by:
      toCompositeData in interface CompositeDataView
      Parameters:
      ct - the CompositeType that the caller expects. This parameter is ignored and can be null.
      Returns:
      the CompositeData representation.