OpenJDK 27 · com.sun.jdi.ObjectReference · APIdia, the JavaDoc alternative

Modifier and Type	Field and Description
public static final int	INVOKE_NONVIRTUAL Perform non-virtual method invocation
public static final int	INVOKE_SINGLE_THREADED Perform method invocation with only the invoking thread resumed

Method Summary

Modifier and Type	Method and Description
public void	disableCollection() Prevents garbage collection for this object.
public void	enableCollection() Permits garbage collection for this object.
public int	Returns: the integer count of the number of entries. entryCount() Returns the number of times this object's monitor has been entered by the current owning thread if the owning thread is platform thread; Returns 0 if not owned by a platform thread.
public boolean	Returns: true if the Object is an ObjectReference, if the ObjectReferences belong to the same VM, and if applying the "==" operator on the mirrored objects in that VM evaluates to true. equals(Object obj) Compares the specified Object with this ObjectReference for equality.
public Value	Returns: the `Value` of the instance field. getValue(Field the field containing the requested value sig) Gets the value of a given instance or static field in this object.
public Map<Field, Value>	Returns: a Map of the requested `Field` objects with their `Value`. getValues(List<? extends Field> a list of `Field` objects containing the requested values. fields) Gets the value of multiple instance and/or static fields in this object.
public int	Returns: the integer hash code hashCode() Returns the hash code value for this ObjectReference.
public Value	Returns: a `Value` mirror of the invoked method's return value. invokeMethod(ThreadReference the thread in which to invoke. thread, Method the `Method` to invoke. method, List<? extends Value> the list of `Value` arguments bound to the invoked method. Values from the list are assigned to arguments in the order they appear in the method signature. arguments, int the integer bit flag options. options) Invokes the specified `Method` on this object in the target VM.
public boolean	Returns: `true` if this `ObjectReference` has been collected; `false` otherwise. isCollected() Determines if this object has been garbage collected in the target VM.
public ThreadReference	Returns: the `ThreadReference` of the platform thread which currently owns the monitor, or null if the monitor is owned by a virtual thread or not owned. owningThread() Returns a `ThreadReference` for the platform thread, if any, which currently owns this object's monitor.
public ReferenceType	Returns: the `ReferenceType` for this object. referenceType() Gets the `ReferenceType` that mirrors the type of this object.
public List<ObjectReference>	Returns: a List of `ObjectReference` objects. If there are no objects that reference this object, a zero-length list is returned.. referringObjects(long The maximum number of referring objects to return. Must be non-negative. If zero, all referring objects are returned. maxReferrers) Returns objects that directly reference this object.
public void	setValue(Field the field containing the requested value field, Value the new value to assign value) Sets the value of a given instance or static field in this object.
public long	Returns: a long unique ID uniqueID() Returns a unique identifier for this ObjectReference.
public List<ThreadReference>	Returns: a List of `ThreadReference` objects. The list has zero length if no threads are waiting for the monitor, or only virtual threads are waiting for the monitor. waitingThreads() Returns a List containing a `ThreadReference` for each platform thread currently waiting for this object's monitor.

Inherited from com.sun.jdi.Value:: type

INVOKE_NONVIRTUAL	back to summary
public static final int INVOKE_NONVIRTUAL Perform non-virtual method invocation

INVOKE_SINGLE_THREADED	back to summary
public static final int INVOKE_SINGLE_THREADED Perform method invocation with only the invoking thread resumed

Method Detail

disableCollection back to summary

disableCollection	back to summary
public void disableCollection() Prevents garbage collection for this object. By default all `ObjectReference` values returned by JDI may be collected at any time the target VM is running. A call to this method guarantees that the object will not be collected. `enableCollection` can be used to allow collection once again. Calls to this method are counted. Every call to this method requires a corresponding call to `enableCollection` before garbage collection is re-enabled. Note that while the target VM is suspended, no garbage collection will occur because all threads are suspended. The typical examination of variables, fields, and arrays during the suspension is safe without explicitly disabling garbage collection. This method should be used sparingly, as it alters the pattern of garbage collection in the target VM and, consequently, may result in application behavior under the debugger that differs from its non-debugged behavior. Exceptions VMCannotBeModifiedException: if the VirtualMachine is read-only - see `VirtualMachine#canBeModified()`.

public void disableCollection()

Prevents garbage collection for this object. By default all ObjectReference values returned by JDI may be collected at any time the target VM is running. A call to this method guarantees that the object will not be collected. enableCollection can be used to allow collection once again.

Calls to this method are counted. Every call to this method requires a corresponding call to enableCollection before garbage collection is re-enabled.

Note that while the target VM is suspended, no garbage collection will occur because all threads are suspended. The typical examination of variables, fields, and arrays during the suspension is safe without explicitly disabling garbage collection.

This method should be used sparingly, as it alters the pattern of garbage collection in the target VM and, consequently, may result in application behavior under the debugger that differs from its non-debugged behavior.

Exceptions

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

enableCollection back to summary

enableCollection	back to summary
public void enableCollection() Permits garbage collection for this object. By default all `ObjectReference` values returned by JDI may be collected at any time the target VM is running. A call to this method is necessary only if garbage collection was previously disabled with `disableCollection`. Exceptions VMCannotBeModifiedException: if the VirtualMachine is read-only - see `VirtualMachine#canBeModified()`.

public void enableCollection()

Permits garbage collection for this object. By default all ObjectReference values returned by JDI may be collected at any time the target VM is running. A call to this method is necessary only if garbage collection was previously disabled with disableCollection.

Exceptions

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

entryCount back to summary

entryCount	back to summary
public int entryCount() throws IncompatibleThreadStateException Returns the number of times this object's monitor has been entered by the current owning thread if the owning thread is platform thread; Returns 0 if not owned by a platform thread. See `ThreadReference#ownedMonitors` for a definition of ownership. Not all target VMs support this operation. See `VirtualMachine#canGetMonitorInfo` to determine if the operation is supported. Returns:int the integer count of the number of entries. Exceptions IncompatibleThreadStateException: if the owning thread is not suspended in the target VM UnsupportedOperationException: if the target VM does not support this operation. See Also `owningThread`

public int entryCount() throws IncompatibleThreadStateException

Returns the number of times this object's monitor has been entered by the current owning thread if the owning thread is platform thread; Returns 0 if not owned by a platform thread. See ThreadReference#ownedMonitors for a definition of ownership.

Not all target VMs support this operation. See VirtualMachine#canGetMonitorInfo to determine if the operation is supported.

Returns:int

the integer count of the number of entries.

Exceptions

IncompatibleThreadStateException:: if the owning thread is not suspended in the target VM
UnsupportedOperationException:: if the target VM does not support this operation.

See Also

owningThread

equals	back to summary
public boolean equals(Object obj) Compares the specified Object with this ObjectReference for equality. Returns:boolean true if the Object is an ObjectReference, if the ObjectReferences belong to the same VM, and if applying the "==" operator on the mirrored objects in that VM evaluates to true.

equals

back to summary

public boolean equals(Object obj)

Compares the specified Object with this ObjectReference for equality.

Returns:boolean: true if the Object is an ObjectReference, if the ObjectReferences belong to the same VM, and if applying the "==" operator on the mirrored objects in that VM evaluates to true.

getValue back to summary

getValue	back to summary
public Value getValue(Field sig) Gets the value of a given instance or static field in this object. The Field must be valid for this ObjectReference; that is, it must be from the mirrored object's class or a superclass of that class. Parameters sig:Field the field containing the requested value Returns:Value the `Value` of the instance field. Exceptions IllegalArgumentException: if the field is not valid for this object's class.

public Value getValue(Field sig)

Gets the value of a given instance or static field in this object. The Field must be valid for this ObjectReference; that is, it must be from the mirrored object's class or a superclass of that class.

Parameters

sig:Field: the field containing the requested value

Returns:Value

the Value of the instance field.

Exceptions

IllegalArgumentException:: if the field is not valid for this object's class.

getValues back to summary

getValues	back to summary
public Map<Field, Value> getValues(List<? extends Field> fields) Gets the value of multiple instance and/or static fields in this object. The Fields must be valid for this ObjectReference; that is, they must be from the mirrored object's class or a superclass of that class. Parameters fields:List<? extends Field> a list of `Field` objects containing the requested values. Returns:Map<Field, Value> a Map of the requested `Field` objects with their `Value`. Exceptions IllegalArgumentException: if any field is not valid for this object's class.

public Map<Field, Value> getValues(List<? extends Field> fields)

Gets the value of multiple instance and/or static fields in this object. The Fields must be valid for this ObjectReference; that is, they must be from the mirrored object's class or a superclass of that class.

Parameters

fields:List<? extends Field>: a list of Field objects containing the requested values.

Returns:Map<Field, Value>

a Map of the requested Field objects with their Value.

Exceptions

IllegalArgumentException:: if any field is not valid for this object's class.

hashCode	back to summary
public int hashCode() Returns the hash code value for this ObjectReference. Returns:int the integer hash code

hashCode

back to summary

public int hashCode()

Returns the hash code value for this ObjectReference.

Returns:int: the integer hash code

invokeMethod back to summary

invokeMethod	back to summary
public Value invokeMethod(ThreadReference thread, Method method, List<? extends Value> arguments, int options) throws InvalidTypeException, ClassNotLoadedException, IncompatibleThreadStateException, InvocationException Invokes the specified `Method` on this object in the target VM. The specified method can be defined in this object's class, in a superclass of this object's class, or in an interface implemented by this object. The method may be a static method or an instance method, but not a static initializer or constructor. Use `ClassType#newInstance` to create a new object and run its constructor. The method invocation will occur in the specified thread. Method invocation can occur only if the specified thread has been suspended by an event which occurred in that thread. Method invocation is not supported when the target VM has been suspended through `VirtualMachine#suspend` or when the specified thread is suspended through `ThreadReference#suspend`. The specified method is invoked with the arguments in the specified argument list. The method invocation is synchronous; this method does not return until the invoked method returns in the target VM. If the invoked method throws an exception, this method will throw an `InvocationException` which contains a mirror to the exception object thrown. Object arguments must be assignment compatible with the argument type (This implies that the argument type must be loaded through the enclosing class's class loader). Primitive arguments must be either assignment compatible with the argument type or must be convertible to the argument type without loss of information. If the method being called accepts a variable number of arguments, then the last argument type is an array of some component type. The argument in the matching position can be omitted, or can be null, an array of the same component type, or an argument of the component type followed by any number of other arguments of the same type. If the argument is omitted, then a 0 length array of the component type is passed. The component type can be a primitive type. Autoboxing is not supported. See section 5.2 of The Java Language Specification for more information on assignment compatibility. By default, the method is invoked using dynamic lookup as documented in section 15.12.4.4 of The Java Language Specification in particular, overriding based on the runtime type of the object mirrored by this `ObjectReference` will occur. This behavior can be changed by specifying the `INVOKE_NONVIRTUAL` bit flag in the `options` argument. If this flag is set, the specified method is invoked whether or not it is overridden for this object's runtime type. The method, in this case, must have an implementation, either in a class or an interface. This option is useful for performing method invocations like those done with the `super` keyword in the Java programming language. By default, all threads in the target VM are resumed while the method is being invoked if they were previously suspended by an event or by `VirtualMachine#suspend` or `ThreadReference#suspend`. This is done to prevent the deadlocks that will occur if any of the threads own resources, such as monitors, that will be needed by the invoked method. Note, however, that this implicit resume acts exactly like `ThreadReference#resume`, so if the thread's suspend count is greater than 1, it will remain in a suspended state during the invocation and thus a deadlock could still occur. By default, when the invocation completes, all threads in the target VM are suspended, regardless their state before the invocation. It is possible that breakpoints or other events might occur during the invocation. This can cause deadlocks as described above. It can also cause a deadlock if invokeMethod is called from the client's event handler thread. In this case, this thread will be waiting for the invokeMethod to complete and won't read the EventSet that comes in for the new event. If this new EventSet is SUSPEND_ALL, then a deadlock will occur because no one will resume the EventSet. To avoid this, all EventRequests should be disabled before doing the invokeMethod, or the invokeMethod should not be done from the client's event handler thread. The resumption of other threads during the invocation can be prevented by specifying the `INVOKE_SINGLE_THREADED` bit flag in the `options` argument; however, there is no protection against or recovery from the deadlocks described above, so this option should be used with great caution. Only the specified thread will be resumed (as described for all threads above). Upon completion of a single threaded invoke, the invoking thread will be suspended once again. Note that any threads started during the single threaded invocation will not be suspended when the invocation completes. If the target VM is disconnected during the invoke (for example, through `VirtualMachine#dispose`) the method invocation continues. API Note Virtual threads are typically user-mode threads scheduled by the Java runtime rather than the operating system. As such, there may be more cases with virtual threads where the `INVOKE_SINGLE_THREADED` option may cause a deadlock. For example, suspending all threads in the target VM may suspend threads that support the timer mechanism for virtual threads, and thus methods such as `Thread#sleep` may deadlock. Parameters thread:ThreadReference the thread in which to invoke. method:Method the `Method` to invoke. arguments:List<? extends Value> the list of `Value` arguments bound to the invoked method. Values from the list are assigned to arguments in the order they appear in the method signature. options:int the integer bit flag options. Returns:Value a `Value` mirror of the invoked method's return value. Exceptions InvalidTypeException: If the arguments do not meet this requirement -- Object arguments must be assignment compatible with the argument type. This implies that the argument type must be loaded through the enclosing class's class loader. Primitive arguments must be either assignment compatible with the argument type or must be convertible to the argument type without loss of information. See JLS section 5.2 for more information on assignment compatibility. ClassNotLoadedException: if any argument type has not yet been loaded through the appropriate class loader. IncompatibleThreadStateException: if the specified thread has not been suspended by an event. InvocationException: if the method invocation resulted in an exception in the target VM. IllegalArgumentException: if the method is not a member of this object's class, if the size of the argument list does not match the number of declared arguments for the method, if the method is a constructor or static initializer, or if `INVOKE_NONVIRTUAL` is specified and the method is abstract. VMCannotBeModifiedException: if the VirtualMachine is read-only - see `VirtualMachine#canBeModified()`.

public Value invokeMethod(ThreadReference thread, Method method, List<? extends Value> arguments, int options) throws InvalidTypeException, ClassNotLoadedException, IncompatibleThreadStateException, InvocationException

Invokes the specified Method on this object in the target VM. The specified method can be defined in this object's class, in a superclass of this object's class, or in an interface implemented by this object. The method may be a static method or an instance method, but not a static initializer or constructor. Use ClassType#newInstance to create a new object and run its constructor.

The method invocation will occur in the specified thread. Method invocation can occur only if the specified thread has been suspended by an event which occurred in that thread. Method invocation is not supported when the target VM has been suspended through VirtualMachine#suspend or when the specified thread is suspended through ThreadReference#suspend.

The specified method is invoked with the arguments in the specified argument list. The method invocation is synchronous; this method does not return until the invoked method returns in the target VM. If the invoked method throws an exception, this method will throw an InvocationException which contains a mirror to the exception object thrown.

Object arguments must be assignment compatible with the argument type (This implies that the argument type must be loaded through the enclosing class's class loader). Primitive arguments must be either assignment compatible with the argument type or must be convertible to the argument type without loss of information. If the method being called accepts a variable number of arguments, then the last argument type is an array of some component type. The argument in the matching position can be omitted, or can be null, an array of the same component type, or an argument of the component type followed by any number of other arguments of the same type. If the argument is omitted, then a 0 length array of the component type is passed. The component type can be a primitive type. Autoboxing is not supported. See section 5.2 of The Java Language Specification for more information on assignment compatibility.

By default, the method is invoked using dynamic lookup as documented in section 15.12.4.4 of The Java Language Specification in particular, overriding based on the runtime type of the object mirrored by this ObjectReference will occur. This behavior can be changed by specifying the INVOKE_NONVIRTUAL bit flag in the options argument. If this flag is set, the specified method is invoked whether or not it is overridden for this object's runtime type. The method, in this case, must have an implementation, either in a class or an interface. This option is useful for performing method invocations like those done with the super keyword in the Java programming language.

By default, all threads in the target VM are resumed while the method is being invoked if they were previously suspended by an event or by VirtualMachine#suspend or ThreadReference#suspend. This is done to prevent the deadlocks that will occur if any of the threads own resources, such as monitors, that will be needed by the invoked method. Note, however, that this implicit resume acts exactly like ThreadReference#resume, so if the thread's suspend count is greater than 1, it will remain in a suspended state during the invocation and thus a deadlock could still occur. By default, when the invocation completes, all threads in the target VM are suspended, regardless their state before the invocation. It is possible that breakpoints or other events might occur during the invocation. This can cause deadlocks as described above. It can also cause a deadlock if invokeMethod is called from the client's event handler thread. In this case, this thread will be waiting for the invokeMethod to complete and won't read the EventSet that comes in for the new event. If this new EventSet is SUSPEND_ALL, then a deadlock will occur because no one will resume the EventSet. To avoid this, all EventRequests should be disabled before doing the invokeMethod, or the invokeMethod should not be done from the client's event handler thread.

The resumption of other threads during the invocation can be prevented by specifying the INVOKE_SINGLE_THREADED bit flag in the options argument; however, there is no protection against or recovery from the deadlocks described above, so this option should be used with great caution. Only the specified thread will be resumed (as described for all threads above). Upon completion of a single threaded invoke, the invoking thread will be suspended once again. Note that any threads started during the single threaded invocation will not be suspended when the invocation completes.

If the target VM is disconnected during the invoke (for example, through VirtualMachine#dispose) the method invocation continues.

API Note

Virtual threads are typically user-mode threads scheduled by the Java runtime rather than the operating system. As such, there may be more cases with virtual threads where the INVOKE_SINGLE_THREADED option may cause a deadlock. For example, suspending all threads in the target VM may suspend threads that support the timer mechanism for virtual threads, and thus methods such as Thread#sleep may deadlock.

Parameters

thread:ThreadReference: the thread in which to invoke.
method:Method: the Method to invoke.
arguments:List<? extends Value>: the list of Value arguments bound to the invoked method. Values from the list are assigned to arguments in the order they appear in the method signature.
options:int: the integer bit flag options.

Returns:Value

a Value mirror of the invoked method's return value.

Exceptions

InvalidTypeException:: If the arguments do not meet this requirement -- Object arguments must be assignment compatible with the argument type. This implies that the argument type must be loaded through the enclosing class's class loader. Primitive arguments must be either assignment compatible with the argument type or must be convertible to the argument type without loss of information. See JLS section 5.2 for more information on assignment compatibility.
ClassNotLoadedException:: if any argument type has not yet been loaded through the appropriate class loader.
IncompatibleThreadStateException:: if the specified thread has not been suspended by an event.
InvocationException:: if the method invocation resulted in an exception in the target VM.
IllegalArgumentException:: if the method is not a member of this object's class, if the size of the argument list does not match the number of declared arguments for the method, if the method is a constructor or static initializer, or if INVOKE_NONVIRTUAL is specified and the method is abstract.
VMCannotBeModifiedException:: if the VirtualMachine is read-only - see VirtualMachine#canBeModified().

isCollected back to summary

isCollected	back to summary
public boolean isCollected() Determines if this object has been garbage collected in the target VM. Returns:boolean `true` if this `ObjectReference` has been collected; `false` otherwise. Exceptions VMCannotBeModifiedException: if the VirtualMachine is read-only - see `VirtualMachine#canBeModified()`.

public boolean isCollected()

Determines if this object has been garbage collected in the target VM.

Returns:boolean

true if this ObjectReference has been collected; false otherwise.

Exceptions

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

owningThread back to summary

owningThread	back to summary
public ThreadReference owningThread() throws IncompatibleThreadStateException Returns a `ThreadReference` for the platform thread, if any, which currently owns this object's monitor. See `ThreadReference#ownedMonitors` for a definition of ownership. Not all target VMs support this operation. See `VirtualMachine#canGetMonitorInfo` to determine if the operation is supported. Returns:ThreadReference the `ThreadReference` of the platform thread which currently owns the monitor, or null if the monitor is owned by a virtual thread or not owned. Exceptions IncompatibleThreadStateException: if the owning thread is not suspended in the target VM UnsupportedOperationException: if the target VM does not support this operation.

public ThreadReference owningThread() throws IncompatibleThreadStateException

Returns a ThreadReference for the platform thread, if any, which currently owns this object's monitor. See ThreadReference#ownedMonitors for a definition of ownership.

Not all target VMs support this operation. See VirtualMachine#canGetMonitorInfo to determine if the operation is supported.

Returns:ThreadReference

the ThreadReference of the platform thread which currently owns the monitor, or null if the monitor is owned by a virtual thread or not owned.

Exceptions

IncompatibleThreadStateException:: if the owning thread is not suspended in the target VM
UnsupportedOperationException:: if the target VM does not support this operation.

referenceType back to summary

referenceType	back to summary
public ReferenceType referenceType() Gets the `ReferenceType` that mirrors the type of this object. The type may be a subclass or implementor of the declared type of any field or variable which currently holds it. For example, right after the following statement. `Object obj = new String("Hello, world!");` The ReferenceType of obj will mirror java.lang.String and not java.lang.Object. The type of an object never changes, so this method will always return the same ReferenceType over the lifetime of the mirrored object. The returned ReferenceType will be a `ClassType` or `ArrayType` and never an `InterfaceType`. Returns:ReferenceType the `ReferenceType` for this object.

public ReferenceType referenceType()

Gets the ReferenceType that mirrors the type of this object. The type may be a subclass or implementor of the declared type of any field or variable which currently holds it. For example, right after the following statement.

Object obj = new String("Hello, world!");

The ReferenceType of obj will mirror java.lang.String and not java.lang.Object.

The type of an object never changes, so this method will always return the same ReferenceType over the lifetime of the mirrored object.

The returned ReferenceType will be a ClassType or ArrayType and never an InterfaceType.

Returns:ReferenceType: the ReferenceType for this object.

referringObjects back to summary

referringObjects	back to summary
public List<ObjectReference> referringObjects(long maxReferrers) Returns objects that directly reference this object. Only objects that are reachable for the purposes of garbage collection are returned. Note that an object can also be referenced in other ways, such as from a local variable in a stack frame, or from a JNI global reference. Such non-object referrers are not returned by this method. Not all target virtual machines support this operation. Use `VirtualMachine#canGetInstanceInfo()` to determine if the operation is supported. Parameters maxReferrers:long The maximum number of referring objects to return. Must be non-negative. If zero, all referring objects are returned. Returns:List<ObjectReference> a List of `ObjectReference` objects. If there are no objects that reference this object, a zero-length list is returned.. Exceptions UnsupportedOperationException: if the target virtual machine does not support this operation - see `VirtualMachine#canGetInstanceInfo()` IllegalArgumentException: if maxReferrers is less than zero. Since 1.6 See Also `VirtualMachine#instanceCounts(List)`, `ReferenceType#instances(long)`

public List<ObjectReference> referringObjects(long maxReferrers)

Returns objects that directly reference this object. Only objects that are reachable for the purposes of garbage collection are returned. Note that an object can also be referenced in other ways, such as from a local variable in a stack frame, or from a JNI global reference. Such non-object referrers are not returned by this method.

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

Parameters

maxReferrers:long: The maximum number of referring objects to return. Must be non-negative. If zero, all referring objects are returned.

Returns:List<ObjectReference>

a List of ObjectReference objects. If there are no objects that reference this object, a zero-length list is returned..

Exceptions

UnsupportedOperationException:: if the target virtual machine does not support this operation - see VirtualMachine#canGetInstanceInfo()
IllegalArgumentException:: if maxReferrers is less than zero.

Since

1.6

setValue back to summary

setValue	back to summary
public void setValue(Field field, Value value) throws InvalidTypeException, ClassNotLoadedException Sets the value of a given instance or static field in this object. The `Field` must be valid for this ObjectReference; that is, it must be from the mirrored object's class or a superclass of that class. The field must not be final. Object values must be assignment compatible with the field type (This implies that the field type must be loaded through the enclosing class's class loader). Primitive values must be either assignment compatible with the field type or must be convertible to the field type without loss of information. See section 5.2 of The Java Language Specification for more information on assignment compatibility. Parameters field:Field the field containing the requested value value:Value the new value to assign Exceptions InvalidTypeException: if the value's type does not match the field's type. ClassNotLoadedException: if 'value' is not null, and the field type has not yet been loaded through the appropriate class loader. IllegalArgumentException: if the field is not valid for this object's class or the field is final. VMCannotBeModifiedException: if the VirtualMachine is read-only - see `VirtualMachine#canBeModified()`.

public void setValue(Field field, Value value) throws InvalidTypeException, ClassNotLoadedException

Sets the value of a given instance or static field in this object. The Field must be valid for this ObjectReference; that is, it must be from the mirrored object's class or a superclass of that class. The field must not be final.

Object values must be assignment compatible with the field type (This implies that the field type must be loaded through the enclosing class's class loader). Primitive values must be either assignment compatible with the field type or must be convertible to the field type without loss of information. See section 5.2 of The Java Language Specification for more information on assignment compatibility.

Parameters

field:Field: the field containing the requested value
value:Value: the new value to assign

Exceptions

InvalidTypeException:: if the value's type does not match the field's type.
ClassNotLoadedException:: if 'value' is not null, and the field type has not yet been loaded through the appropriate class loader.
IllegalArgumentException:: if the field is not valid for this object's class or the field is final.
VMCannotBeModifiedException:: if the VirtualMachine is read-only - see VirtualMachine#canBeModified().

uniqueID	back to summary
public long uniqueID() Returns a unique identifier for this ObjectReference. It is guaranteed to be unique among all ObjectReferences from the same VM that have not yet been disposed. The guarantee applies as long as this ObjectReference has not yet been disposed. Returns:long a long unique ID

uniqueID

back to summary

public long uniqueID()

Returns a unique identifier for this ObjectReference. It is guaranteed to be unique among all ObjectReferences from the same VM that have not yet been disposed. The guarantee applies as long as this ObjectReference has not yet been disposed.

Returns:long: a long unique ID

waitingThreads back to summary

waitingThreads	back to summary
public List<ThreadReference> waitingThreads() throws IncompatibleThreadStateException Returns a List containing a `ThreadReference` for each platform thread currently waiting for this object's monitor. See `ThreadReference#currentContendedMonitor` for information about when a thread is considered to be waiting for a monitor. Not all target VMs support this operation. See `VirtualMachine#canGetMonitorInfo` to determine if the operation is supported. Returns:List<ThreadReference> a List of `ThreadReference` objects. The list has zero length if no threads are waiting for the monitor, or only virtual threads are waiting for the monitor. Exceptions IncompatibleThreadStateException: if any waiting thread is not suspended in the target VM UnsupportedOperationException: if the target VM does not support this operation.

public List<ThreadReference> waitingThreads() throws IncompatibleThreadStateException

Returns a List containing a ThreadReference for each platform thread currently waiting for this object's monitor. See ThreadReference#currentContendedMonitor for information about when a thread is considered to be waiting for a monitor.

Not all target VMs support this operation. See VirtualMachine#canGetMonitorInfo to determine if the operation is supported.

Returns:List<ThreadReference>

a List of ThreadReference objects. The list has zero length if no threads are waiting for the monitor, or only virtual threads are waiting for the monitor.

Exceptions

IncompatibleThreadStateException:: if any waiting thread is not suspended in the target VM
UnsupportedOperationException:: if the target VM does not support this operation.

public Interface ObjectReference

Field Summary

Method Summary

Field Detail

Method Detail