Interface VirtualMachine

All Superinterfaces:
Mirror
All Known Subinterfaces:
PathSearchingVirtualMachine
public interface VirtualMachine
extends Mirror

A virtual machine targeted for debugging. More precisely, a mirror representing the composite state of the target VM. All other mirrors are associated with an instance of this interface. Access to all other mirrors is achieved directly or indirectly through an instance of this interface. Access to global VM properties and control of VM execution are supported directly by this interface.

Instances of this interface are created by instances of Connector. For example, an AttachingConnector attaches to a target VM and returns its virtual machine mirror. A Connector will typically create a VirtualMachine by invoking the VirtualMachineManager's VirtualMachineManager.createVirtualMachine(Connection) createVirtualMachine(Connection) method.

Note that a target VM launched by a launching connector is not guaranteed to be stable until after the VMStartEvent has been received.

Any method on VirtualMachine which takes VirtualMachine as an parameter may throw VMDisconnectedException if the target VM is disconnected and the VMDisconnectEvent has been or is available to be read from the EventQueue.

Any method on VirtualMachine which takes VirtualMachine as an parameter may throw VMOutOfMemoryException if the target VM has run out of memory.

Since:
1.3

Fields

Modifier and Type Field Description
static int TRACE_ALL

All tracing is enabled.
static int TRACE_EVENTS

Tracing enabled for internal event handling.
static int TRACE_NONE

All tracing is disabled.
static int TRACE_OBJREFS

Tracing enabled for internal management of object references.
static int TRACE_RECEIVES

Tracing enabled for JDWP packets received from target VM.
static int TRACE_REFTYPES

Tracing enabled for internal managment of reference types.
static int TRACE_SENDS

Tracing enabled for JDWP packets sent to target VM.

Methods

Modifier and Type Method Description
List<ReferenceType> allClasses()

Returns all loaded types.
default List<ModuleReference> allModules()

Returns all modules.
List<ThreadReference> allThreads()

Returns a list of the currently running threads.
boolean canAddMethod()

Determines if the target VM supports the addition of methods when performing class redefinition.
boolean canBeModified()

Determines if the target VM is a read-only VM.
boolean canForceEarlyReturn()

Determines if the target VM supports the forcing of a method to return early.
boolean canGetBytecodes()

Determines if the target VM supports the retrieval of a method's bytecodes.
boolean canGetClassFileVersion()

Determines if the target VM supports reading class file major and minor versions.
boolean canGetConstantPool()

Determines if the target VM supports getting constant pool information of a class.
boolean canGetCurrentContendedMonitor()

Determines if the target VM supports the retrieval of the monitor for which a thread is currently waiting.
boolean canGetInstanceInfo()

Determines if the target VM supports the accessing of class instances, instance counts, and referring objects.
boolean canGetMethodReturnValues()

Determines if the target VM supports the inclusion of return values in MethodExitEvents.
default boolean canGetModuleInfo()

Determines if the target VM supports getting information about modules.
boolean canGetMonitorFrameInfo()

Determines if the target VM supports getting which frame has acquired a monitor.
boolean canGetMonitorInfo()

Determines if the target VM supports the retrieval of the monitor information for an object.
boolean canGetOwnedMonitorInfo()

Determines if the target VM supports the retrieval of the monitors owned by a thread.
boolean canGetSourceDebugExtension()

Determines if the target VM supports getting the source debug extension.
boolean canGetSyntheticAttribute()

Determines if the target VM supports the query of the synthetic attribute of a method or field.
boolean canPopFrames()

Determines if the target VM supports popping frames of a threads stack.
boolean canRedefineClasses()

Determines if the target VM supports any level of class redefinition.
boolean canRequestMonitorEvents()

Determines if the target VM supports the creation of MonitorContendedEnterRequests.
boolean canRequestVMDeathEvent()

Determines if the target VM supports the creation of VMDeathRequests.
boolean canUnrestrictedlyRedefineClasses()

Determines if the target VM supports changes when performing class redefinition that are otherwise restricted by redefineClasses(java.util.Map<? extends com.sun.jdi.ReferenceType, byte[]>).
boolean canUseInstanceFilters()

Determines if the target VM supports filtering events by specific instance object.
boolean canUseSourceNameFilters()

Determines if the target VM supports the filtering of class prepare events by source name.
boolean canWatchFieldAccess()

Determines if the target VM supports watchpoints for field access.
boolean canWatchFieldModification()

Determines if the target VM supports watchpoints for field modification.
List<ReferenceType> classesByName​(String className)

Returns the loaded reference types that match a given name.
String description()

Returns text information on the target VM and the debugger support that mirrors it.
void dispose()

Invalidates this virtual machine mirror.
EventQueue eventQueue()

Returns the event queue for this virtual machine.
EventRequestManager eventRequestManager()

Returns the event request manager for this virtual machine.
void exit​(int exitCode)

Causes the mirrored VM to terminate with the given error code.
String getDefaultStratum()

Return this VM's default stratum.
long[] instanceCounts​(List<? extends ReferenceType> refTypes)

Returns the number of instances of each ReferenceType in the 'refTypes' list.
BooleanValue mirrorOf​(boolean value)

Creates a BooleanValue for the given value.
ByteValue mirrorOf​(byte value)

Creates a ByteValue for the given value.
CharValue mirrorOf​(char value)

Creates a CharValue for the given value.
DoubleValue mirrorOf​(double value)

Creates a DoubleValue for the given value.
FloatValue mirrorOf​(float value)

Creates a FloatValue for the given value.
IntegerValue mirrorOf​(int value)

Creates an IntegerValue for the given value.
LongValue mirrorOf​(long value)

Creates a LongValue for the given value.
ShortValue mirrorOf​(short value)

Creates a ShortValue for the given value.
StringReference mirrorOf​(String value)

Creates a string in this virtual machine.
VoidValue mirrorOfVoid()

Creates a VoidValue.
String name()

Returns the name of the target VM as reported by the property java.vm.name.
Process process()

Returns the Process object for this virtual machine if launched by a LaunchingConnector
void redefineClasses​(Map<? extends ReferenceType,​byte[]> classToBytes)

All classes given are redefined according to the definitions supplied.
void resume()

Continues the execution of the application running in this virtual machine.
void setDebugTraceMode​(int traceFlags)

Traces the activities performed by the com.sun.jdi implementation.
void setDefaultStratum​(String stratum)

Set this VM's default stratum (see Location for a discussion of strata).
void suspend()

Suspends the execution of the application running in this virtual machine.
List<ThreadGroupReference> topLevelThreadGroups()

Returns each thread group which does not have a parent.
String version()

Returns the version of the Java Runtime Environment in the target VM as reported by the property java.version.

Methods declared in interface com.sun.jdi.Mirror

toString, virtualMachine

Fields

TRACE_NONE

static final int TRACE_NONE

All tracing is disabled.

See Also:
Constant Field Values

TRACE_SENDS

static final int TRACE_SENDS

Tracing enabled for JDWP packets sent to target VM.

See Also:
Constant Field Values

TRACE_RECEIVES

static final int TRACE_RECEIVES

Tracing enabled for JDWP packets received from target VM.

See Also:
Constant Field Values

TRACE_EVENTS

static final int TRACE_EVENTS

Tracing enabled for internal event handling.

See Also:
Constant Field Values

TRACE_REFTYPES

static final int TRACE_REFTYPES

Tracing enabled for internal managment of reference types.

See Also:
Constant Field Values

TRACE_OBJREFS

static final int TRACE_OBJREFS

Tracing enabled for internal management of object references.

See Also:
Constant Field Values

TRACE_ALL

static final int TRACE_ALL

All tracing is enabled.

See Also:
Constant Field Values

Methods

allModules

default List<ModuleReference> allModules()

Returns all modules. For each module in the target VM a ModuleReference will be placed in the returned list.

Not all target virtual machines support this operation. Use canGetModuleInfo() to determine if the operation is supported.

Implementation Requirements:
The default implementation throws UnsupportedOperationException.
Returns:
a list of ModuleReference objects, each mirroring a module in the target VM.
Throws:
UnsupportedOperationException - if the target virtual machine does not support this operation.
Since:
9

classesByName

List<ReferenceType> classesByName(String className)

Returns the loaded reference types that match a given name. The name must be fully qualified (for example, java.lang.String). The returned list will contain a ReferenceType for each class or interface found with the given name. The search is confined to loaded classes only; no attempt is made to load a class of the given name.

The returned list will include reference types loaded at least to the point of preparation and types (like array) for which preparation is not defined.

Parameters:
className - the class/interface name to search for
Returns:
a list of ReferenceType objects, each mirroring a type in the target VM with the given name.

allClasses

List<ReferenceType> allClasses()

Returns all loaded types. For each loaded type in the target VM a ReferenceType will be placed in the returned list. The list will include ReferenceTypes which mirror classes, interfaces, and array types.

The returned list will include reference types loaded at least to the point of preparation and types (like array) for which preparation is not defined.

Returns:
a list of ReferenceType objects, each mirroring a loaded type in the target VM.

redefineClasses

void redefineClasses(Map<? extends ReferenceType,​byte[]> classToBytes)

All classes given are redefined according to the definitions supplied. A method in a redefined class is called 'equivalent' (to the old version of the method) if

  • their bytecodes are the same except for indicies into the constant pool, and
  • the referenced constants are equal.
Otherwise, the new method is called 'non-equivalent'. If a redefined method has active stack frames, those active frames continue to run the bytecodes of the previous version of the method. If the new version of such a method is non-equivalent, then a method from one of these active frames is called 'obsolete' and Method.isObsolete() will return true when called on one of these methods. If resetting such a frame is desired, use ThreadReference.popFrames(StackFrame) to pop the old obsolete method execution from the stack. New invocations of redefined methods will always invoke the new versions.

This function does not cause any initialization except that which would occur under the customary JVM semantics. In other words, redefining a class does not cause its initializers to be run. The values of preexisting static variables will remain as they were prior to the call. However, completely uninitialized (new) static variables will be assigned their default value.

If a redefined class has instances then all those instances will have the fields defined by the redefined class at the completion of the call. Preexisting fields will retain their previous values. Any new fields will have their default values; no instance initializers or constructors are run.

Threads need not be suspended.

No events are generated by this function.

All breakpoints in the redefined classes are deleted.

Not all target virtual machines support this operation. Use canRedefineClasses() to determine if the operation is supported. Use canAddMethod() to determine if the redefinition can add methods. Use canUnrestrictedlyRedefineClasses() to determine if the redefinition can change the schema, delete methods, change the class hierarchy, etc.

Parameters:
classToBytes - A map from ReferenceType to array of byte. The bytes represent the new class definition and are in Java Virtual Machine class file format.
Throws:
UnsupportedOperationException - if the target virtual machine does not support this operation.
  • If canRedefineClasses() is false any call of this method will throw this exception.
  • If canAddMethod() is false attempting to add a method will throw this exception.
  • If canUnrestrictedlyRedefineClasses() is false, attempting any of the following will throw this exception
    • changing the schema (the fields)
    • changing the hierarchy (superclasses, interfaces)
    • deleting a method
    • changing class modifiers
    • changing method modifiers
    • changing the NestHost or NestMembers class attributes
NoClassDefFoundError - if the bytes don't correspond to the reference type (the names don't match).
VerifyError - if a "verifier" detects that a class, though well formed, contains an internal inconsistency or security problem.
ClassFormatError - if the bytes do not represent a valid class.
ClassCircularityError - if a circularity has been detected while initializing a class.
UnsupportedClassVersionError - if the major and minor version numbers in bytes are not supported by the VM.
VMCannotBeModifiedException - if the VirtualMachine is read-only - see canBeModified().
Since:
1.4
See Also:
Method.isObsolete(), ThreadReference.popFrames(com.sun.jdi.StackFrame), canRedefineClasses(), canAddMethod(), canUnrestrictedlyRedefineClasses()

allThreads

List<ThreadReference> allThreads()

Returns a list of the currently running threads. For each running thread in the target VM, a ThreadReference that mirrors it is placed in the list. The returned list contains threads created through java.lang.Thread, all native threads attached to the target VM through JNI, and system threads created by the target VM. Thread objects that have not yet been started (see Thread.start()) and thread objects that have completed their execution are not included in the returned list.

Returns:
a list of ThreadReference objects, one for each running thread in the mirrored VM.

suspend

void suspend()

Suspends the execution of the application running in this virtual machine. All threads currently running will be suspended.

Unlike Thread.suspend(), suspends of both the virtual machine and individual threads are counted. Before a thread will run again, it must be resumed (through resume() or ThreadReference.resume()) the same number of times it has been suspended.

Throws:
VMCannotBeModifiedException - if the VirtualMachine is read-only - see canBeModified().

resume

void resume()

Continues the execution of the application running in this virtual machine. All threads are resumed as documented in ThreadReference.resume().

Throws:
VMCannotBeModifiedException - if the VirtualMachine is read-only - see canBeModified().
See Also:
suspend()

topLevelThreadGroups

List<ThreadGroupReference> topLevelThreadGroups()

Returns each thread group which does not have a parent. For each top level thread group a ThreadGroupReference is placed in the returned list.

This command may be used as the first step in building a tree (or trees) of the existing thread groups.

Returns:
a list of ThreadGroupReference objects, one for each top level thread group.

eventQueue

EventQueue eventQueue()

Returns the event queue for this virtual machine. A virtual machine has only one EventQueue object, this method will return the same instance each time it is invoked.

Returns:
the EventQueue for this virtual machine.
Throws:
VMCannotBeModifiedException - if the VirtualMachine is read-only - see canBeModified().

eventRequestManager

EventRequestManager eventRequestManager()

Returns the event request manager for this virtual machine. The EventRequestManager controls user settable events such as breakpoints. A virtual machine has only one EventRequestManager object, this method will return the same instance each time it is invoked.

Returns:
the EventRequestManager for this virtual machine.
Throws:
VMCannotBeModifiedException - if the VirtualMachine is read-only - see canBeModified().

mirrorOf

BooleanValue mirrorOf(boolean value)

Creates a BooleanValue for the given value. This value can be used for setting and comparing against a value retrieved from a variable or field in this virtual machine.

Parameters:
value - a boolean for which to create the value
Returns:
the BooleanValue for the given boolean.

mirrorOf

ByteValue mirrorOf(byte value)

Creates a ByteValue for the given value. This value can be used for setting and comparing against a value retrieved from a variable or field in this virtual machine.

Parameters:
value - a byte for which to create the value
Returns:
the ByteValue for the given byte.

mirrorOf

CharValue mirrorOf(char value)

Creates a CharValue for the given value. This value can be used for setting and comparing against a value retrieved from a variable or field in this virtual machine.

Parameters:
value - a char for which to create the value
Returns:
the CharValue for the given char.

mirrorOf

ShortValue mirrorOf(short value)

Creates a ShortValue for the given value. This value can be used for setting and comparing against a value retrieved from a variable or field in this virtual machine.

Parameters:
value - a short for which to create the value
Returns:
the ShortValue for the given short.

mirrorOf

IntegerValue mirrorOf(int value)

Creates an IntegerValue for the given value. This value can be used for setting and comparing against a value retrieved from a variable or field in this virtual machine.

Parameters:
value - an int for which to create the value
Returns:
the IntegerValue for the given int.

mirrorOf

LongValue mirrorOf(long value)

Creates a LongValue for the given value. This value can be used for setting and comparing against a value retrieved from a variable or field in this virtual machine.

Parameters:
value - a long for which to create the value
Returns:
the LongValue for the given long.

mirrorOf

FloatValue mirrorOf(float value)

Creates a FloatValue for the given value. This value can be used for setting and comparing against a value retrieved from a variable or field in this virtual machine.

Parameters:
value - a float for which to create the value
Returns:
the FloatValue for the given float.

mirrorOf

DoubleValue mirrorOf(double value)

Creates a DoubleValue for the given value. This value can be used for setting and comparing against a value retrieved from a variable or field in this virtual machine.

Parameters:
value - a double for which to create the value
Returns:
the DoubleValue for the given double.

mirrorOf

StringReference mirrorOf(String value)

Creates a string in this virtual machine. The created string can be used for setting and comparing against a string value retrieved from a variable or field in this virtual machine.

Parameters:
value - the string to be created
Returns:
a StringReference that mirrors the newly created string in the target VM.
Throws:
VMCannotBeModifiedException - if the VirtualMachine is read-only -see canBeModified().

mirrorOfVoid

VoidValue mirrorOfVoid()

Creates a VoidValue. This value can be passed to ThreadReference.forceEarlyReturn(com.sun.jdi.Value) when a void method is to be exited.

Returns:
the VoidValue.

process

Process process()

Returns the Process object for this virtual machine if launched by a LaunchingConnector

Returns:
the Process object for this virtual machine, or null if it was not launched by a LaunchingConnector.
Throws:
VMCannotBeModifiedException - if the VirtualMachine is read-only -see canBeModified().

dispose

void dispose()

Invalidates this virtual machine mirror. The communication channel to the target VM is closed, and the target VM prepares to accept another subsequent connection from this debugger or another debugger, including the following tasks:

Any current method invocations executing in the target VM are continued after the disconnection. Upon completion of any such method invocation, the invoking thread continues from the location where it was originally stopped.

Resources originating in this VirtualMachine (ObjectReferences, ReferenceTypes, etc.) will become invalid.

exit

void exit(int exitCode)

Causes the mirrored VM to terminate with the given error code. All resources associated with this VirtualMachine are freed. If the mirrored VM is remote, the communication channel to it will be closed. Resources originating in this VirtualMachine (ObjectReferences, ReferenceTypes, etc.) will become invalid.

Threads running in the mirrored VM are abruptly terminated. A thread death exception is not thrown and finally blocks are not run.

Parameters:
exitCode - the exit code for the target VM. On some platforms, the exit code might be truncated, for example, to the lower order 8 bits.
Throws:
VMCannotBeModifiedException - if the VirtualMachine is read-only - see canBeModified().

canWatchFieldModification

boolean canWatchFieldModification()

Determines if the target VM supports watchpoints for field modification.

Returns:
true if the feature is supported, false otherwise.

canWatchFieldAccess

boolean canWatchFieldAccess()

Determines if the target VM supports watchpoints for field access.

Returns:
true if the feature is supported, false otherwise.

canGetBytecodes

boolean canGetBytecodes()

Determines if the target VM supports the retrieval of a method's bytecodes.

Returns:
true if the feature is supported, false otherwise.

canGetSyntheticAttribute

boolean canGetSyntheticAttribute()

Determines if the target VM supports the query of the synthetic attribute of a method or field.

Returns:
true if the feature is supported, false otherwise.

canGetOwnedMonitorInfo

boolean canGetOwnedMonitorInfo()

Determines if the target VM supports the retrieval of the monitors owned by a thread.

Returns:
true if the feature is supported, false otherwise.

canGetCurrentContendedMonitor

boolean canGetCurrentContendedMonitor()

Determines if the target VM supports the retrieval of the monitor for which a thread is currently waiting.

Returns:
true if the feature is supported, false otherwise.

canGetMonitorInfo

boolean canGetMonitorInfo()

Determines if the target VM supports the retrieval of the monitor information for an object.

Returns:
true if the feature is supported, false otherwise.

canUseInstanceFilters

boolean canUseInstanceFilters()

Determines if the target VM supports filtering events by specific instance object. For example, see BreakpointRequest.addInstanceFilter(com.sun.jdi.ObjectReference).

Returns:
true if the feature is supported, false otherwise.

canRedefineClasses

boolean canRedefineClasses()

Determines if the target VM supports any level of class redefinition.

Returns:
true if the feature is supported, false otherwise.
Since:
1.4
See Also:
redefineClasses(java.util.Map<? extends com.sun.jdi.ReferenceType, byte[]>)

canAddMethod

boolean canAddMethod()

Determines if the target VM supports the addition of methods when performing class redefinition.

Returns:
true if the feature is supported, false otherwise.
Since:
1.4
See Also:
redefineClasses(java.util.Map<? extends com.sun.jdi.ReferenceType, byte[]>)

canUnrestrictedlyRedefineClasses

boolean canUnrestrictedlyRedefineClasses()

Determines if the target VM supports changes when performing class redefinition that are otherwise restricted by redefineClasses(java.util.Map<? extends com.sun.jdi.ReferenceType, byte[]>).

Returns:
true if the feature is supported, false otherwise.
Since:
1.4
See Also:
redefineClasses(java.util.Map<? extends com.sun.jdi.ReferenceType, byte[]>)

canPopFrames

boolean canPopFrames()

Determines if the target VM supports popping frames of a threads stack.

Returns:
true if the feature is supported, false otherwise.
Since:
1.4
See Also:
ThreadReference.popFrames(com.sun.jdi.StackFrame)

canGetSourceDebugExtension

boolean canGetSourceDebugExtension()

Determines if the target VM supports getting the source debug extension.

Returns:
true if the feature is supported, false otherwise.
Since:
1.4
See Also:
ReferenceType.sourceDebugExtension()

canRequestVMDeathEvent

boolean canRequestVMDeathEvent()

Determines if the target VM supports the creation of VMDeathRequests.

Returns:
true if the feature is supported, false otherwise.
Since:
1.4
See Also:
EventRequestManager.createVMDeathRequest()

canGetMethodReturnValues

boolean canGetMethodReturnValues()

Determines if the target VM supports the inclusion of return values in MethodExitEvents.

Returns:
true if the feature is supported, false otherwise.
Since:
1.6
See Also:
EventRequestManager.createMethodExitRequest()

canGetInstanceInfo

boolean canGetInstanceInfo()

Determines if the target VM supports the accessing of class instances, instance counts, and referring objects.

Returns:
true if the feature is supported, false otherwise.
Since:
1.6
See Also:
instanceCounts(java.util.List<? extends com.sun.jdi.ReferenceType>), ReferenceType.instances(long), ObjectReference.referringObjects(long)

canUseSourceNameFilters

boolean canUseSourceNameFilters()

Determines if the target VM supports the filtering of class prepare events by source name. see ClassPrepareRequest.addSourceNameFilter(java.lang.String).

Returns:
true if the feature is supported, false otherwise.
Since:
1.6

canForceEarlyReturn

boolean canForceEarlyReturn()

Determines if the target VM supports the forcing of a method to return early.

Returns:
true if the feature is supported, false otherwise.
Since:
1.6
See Also:
ThreadReference.forceEarlyReturn(Value)

canBeModified

boolean canBeModified()

Determines if the target VM is a read-only VM. If a method which would modify the state of the VM is called on a read-only VM, then VMCannotBeModifiedException is thrown.

Returns:
true if the feature is supported, false otherwise.
Since:
1.5

canRequestMonitorEvents

boolean canRequestMonitorEvents()

Determines if the target VM supports the creation of MonitorContendedEnterRequests. MonitorContendedEnteredRequests. MonitorWaitRequests. MonitorWaitedRequests.

Returns:
true if the feature is supported, false otherwise.
Since:
1.6
See Also:
EventRequestManager.createMonitorContendedEnterRequest(), EventRequestManager.createMonitorContendedEnteredRequest(), EventRequestManager.createMonitorWaitRequest(), EventRequestManager.createMonitorWaitedRequest()

canGetMonitorFrameInfo

boolean canGetMonitorFrameInfo()

Determines if the target VM supports getting which frame has acquired a monitor.

Returns:
true if the feature is supported, false otherwise.
Since:
1.6
See Also:
ThreadReference.ownedMonitorsAndFrames()

canGetClassFileVersion

boolean canGetClassFileVersion()

Determines if the target VM supports reading class file major and minor versions.

Returns:
true if the feature is supported, false otherwise.
Since:
1.6
See Also:
ReferenceType.majorVersion(), ReferenceType.minorVersion()

canGetConstantPool

boolean canGetConstantPool()

Determines if the target VM supports getting constant pool information of a class.

Returns:
true if the feature is supported, false otherwise.
Since:
1.6
See Also:
ReferenceType.constantPoolCount(), ReferenceType.constantPool()

canGetModuleInfo

default boolean canGetModuleInfo()

Determines if the target VM supports getting information about modules.

Implementation Requirements:
The default implementation returns false.
Returns:
true if the feature is supported, false otherwise
Since:
9
See Also:
allModules(), ReferenceType.module(), ModuleReference

setDefaultStratum

void setDefaultStratum(String stratum)

Set this VM's default stratum (see Location for a discussion of strata). Overrides the per-class default set in the class file.

Affects location queries (such as, Location.sourceName()) and the line boundaries used in single stepping.

Parameters:
stratum - the stratum to set as VM default, or null to use per-class defaults.
Throws:
UnsupportedOperationException - if the target virtual machine does not support this operation.
Since:
1.4

getDefaultStratum

String getDefaultStratum()

Return this VM's default stratum.

Returns:
null (meaning that the per-class default - ReferenceType.defaultStratum() - should be used) unless the default stratum has been set with setDefaultStratum(String).
Since:
1.4
See Also:
setDefaultStratum(String), ReferenceType.defaultStratum()

instanceCounts

long[] instanceCounts(List<? extends ReferenceType> refTypes)

Returns the number of instances of each ReferenceType in the 'refTypes' list. Only instances that are reachable for the purposes of garbage collection are counted.

Not all target virtual machines support this operation. Use canGetInstanceInfo() to determine if the operation is supported.

Parameters:
refTypes - the list of ReferenceType objects for which counts are to be obtained.
Returns:
an array of long containing one element for each element in the 'refTypes' list. Element i of the array contains the number of instances in the target VM of the ReferenceType at position i in the 'refTypes' list. If the 'refTypes' list is empty, a zero-length array is returned. If a ReferenceType in refTypes has been garbage collected, zero is returned for its instance count.
Throws:
UnsupportedOperationException - if the target virtual machine does not support this operation - see canGetInstanceInfo()
NullPointerException - if the 'refTypes' list is null.
Since:
1.6
See Also:
ReferenceType.instances(long), ObjectReference.referringObjects(long)

description

String description()

Returns text information on the target VM and the debugger support that mirrors it. No specific format for this information is guaranteed. Typically, this string contains version information for the target VM and debugger interfaces. More precise information on VM and JDI versions is available through version(), VirtualMachineManager.majorInterfaceVersion(), and VirtualMachineManager.minorInterfaceVersion()

Returns:
the description.

version

String version()

Returns the version of the Java Runtime Environment in the target VM as reported by the property java.version. For obtaining the JDI interface version, use VirtualMachineManager.majorInterfaceVersion() and VirtualMachineManager.minorInterfaceVersion()

Returns:
the target VM version.

name

String name()

Returns the name of the target VM as reported by the property java.vm.name.

Returns:
the target VM name.

setDebugTraceMode

void setDebugTraceMode(int traceFlags)

Traces the activities performed by the com.sun.jdi implementation. All trace information is output to System.err. The given trace flags are used to limit the output to only the information desired. The given flags are in effect and the corresponding trace will continue until the next call to this method.

Output is implementation dependent and trace mode may be ignored.

Parameters:
traceFlags - identifies which kinds of tracing to enable.

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Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/11/docs/api/jdk.jdi/com/sun/jdi/VirtualMachine.html