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

  • Field Details

    • TRACE_NONE

      static final int TRACE_NONE
      All tracing is disabled.
      See Also:

    • TRACE_SENDS

      static final int TRACE_SENDS
      Tracing enabled for JDWP packets sent to target VM.
      See Also:

    • TRACE_RECEIVES

      static final int TRACE_RECEIVES
      Tracing enabled for JDWP packets received from target VM.
      See Also:

    • TRACE_EVENTS

      static final int TRACE_EVENTS
      Tracing enabled for internal event handling.
      See Also:

    • TRACE_REFTYPES

      static final int TRACE_REFTYPES
      Tracing enabled for internal management of reference types.
      See Also:

    • TRACE_OBJREFS

      static final int TRACE_OBJREFS
      Tracing enabled for internal management of object references.
      See Also:

    • TRACE_ALL

      static final int TRACE_ALL
      All tracing is enabled.
      See Also:

  • Method Details

    • 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 in the target VM.

      The returned list includes all reference types, including hidden classes or interfaces, 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.
      See Also:

    • 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 indices 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.
      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:

    • allThreads

      List<ThreadReference> allThreads()
      Returns a list of the live threads in the target VM. Threads that have not yet started or threads that have terminated are not included in the list.

      The returned list contains a ThreadReference for each live platform thread in the target VM. This includes platform threads created with the java.lang.Thread API and all native threads attached to the target VM with JNI code.

      It is implementation dependent if the list contains elements for live virtual threads in the target VM. The target VM may not return any references to virtual threads, or it may be configured to return a reference to some or all virtual threads. Tools that want to track all virtual threads may enable ThreadStartRequest and ThreadDeathRequest to get notifications when virtual threads start and terminate.

      Returns:
      a list of ThreadReference objects for the threads in the target VM

    • suspend

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

      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 Also:

    • 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 Also:

    • 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:

    • canAddMethod

      @Deprecated(since="15") boolean canAddMethod()
      Deprecated.
      A JVM TI based JDWP back-end will never set this capability to true.
      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:

    • canUnrestrictedlyRedefineClasses

      @Deprecated(since="15") boolean canUnrestrictedlyRedefineClasses()
      Deprecated.
      A JVM TI based JDWP back-end will never set this capability to true.
      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:

    • 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:

    • 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:

    • 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:

    • 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:

    • 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:

    • canUseSourceNameFilters

      boolean canUseSourceNameFilters()
      Determines if the target VM supports the filtering of class prepare events by source name.
      Returns:
      true if the feature is supported, false otherwise.
      Since:
      1.6
      See Also:

    • 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:

    • 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:

    • 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:

    • 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:

    • 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:

    • 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:

    • 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:

    • 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:

    • 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.