OpenJDK 27 · sun.jvm.hotspot.types.Field · APIdia, the JavaDoc alternative

This is the basic interface which describes a field in a C/C++ data structure or a Java object.

The accessors in this class are designed to allow manual coercion of the data within the field, which is often necessary when interfacing with C programs. Therefore, the accessors here do not perform any type checking. Specializations of the Field interface, such as JByteField, provide getValue() methods which both perform type checking and return the appropriate specialized type.

See @see CIntegerType for a description of why all C integer types are bundled into the category "CIntegerType".

As an example, coercing a pointer field into an int can be done in the following fashion (assuming the application has registered an integer type in the type database called "intptr_t"):

{
  ...
  Address myObject = ...;
  CIntegerType intptr_tType = (CIntegerType) db.lookupType("intptr_t");
  long addrVal = field.getCInteger(myObject, intptr_tType);
  ...
}

FIXME: among other things, this interface is not sufficient to describe fields which are themselves arrays (like Symbol's u1 _body[1]).

Method Summary

Modifier and Type	Method and Description
public Address	getAddress(Address addr)
public Address	getAddress()
public long	getCInteger(Address addr, CIntegerType type)
public long	getCInteger(CIntegerType type)
public boolean	getJBoolean(Address addr) These accessors require that the field be nonstatic; otherwise, a WrongTypeException will be thrown.
public boolean	getJBoolean() These accessors require that the field be static; otherwise, a WrongTypeException will be thrown.
public byte	getJByte(Address addr)
public byte	getJByte()
public char	getJChar(Address addr)
public char	getJChar()
public double	getJDouble(Address addr)
public double	getJDouble()
public float	getJFloat(Address addr)
public float	getJFloat()
public int	getJInt(Address addr)
public int	getJInt()
public long	getJLong(Address addr)
public long	getJLong()
public short	getJShort(Address addr)
public short	getJShort()
public String	getName() Get the name of this field
public OopHandle	getNarrowOopHandle(Address addr)
public OopHandle	getNarrowOopHandle()
public long	getOffset() The offset of this field, in bytes, in its containing data structure, if nonstatic.
public OopHandle	getOopHandle(Address addr)
public OopHandle	getOopHandle()
public long	getSize() Get the size, in bytes, of this field.
public Address	getStaticFieldAddress() The address of this field, if it is a static field.
public Type	getType() Get the type of this field
public boolean	isStatic() Is this a static field?

Method Detail

getAddress	back to summary
public Address getAddress(Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getAddress	back to summary
public Address getAddress() throws UnmappedAddressException, UnalignedAddressException

getCInteger	back to summary
public long getCInteger(Address addr, CIntegerType type) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getCInteger	back to summary
public long getCInteger(CIntegerType type) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getJBoolean	back to summary
public boolean getJBoolean(Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException These accessors require that the field be nonstatic; otherwise, a WrongTypeException will be thrown. Note that type checking is not performed by these accessors in order to allow manual type coercion of field data. For better protection when accessing primitive fields, use the get(Type)Field accessors in Type.java. NOTE that the Address passed in to these routines may, in fact, be an OopHandle. Specifically, in a reflective system, dereferencing operations applied to the OopHandle must be performed atomically with respect to GC. See @see CIntegerType for a description of why all C integer types are bundled into the category "CIntegerType".

getJBoolean

back to summary

public boolean getJBoolean(Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

These accessors require that the field be nonstatic; otherwise, a WrongTypeException will be thrown. Note that type checking is not performed by these accessors in order to allow manual type coercion of field data. For better protection when accessing primitive fields, use the get(Type)Field accessors in Type.java.

NOTE that the Address passed in to these routines may, in fact, be an OopHandle. Specifically, in a reflective system, dereferencing operations applied to the OopHandle must be performed atomically with respect to GC.

See @see CIntegerType for a description of why all C integer types are bundled into the category "CIntegerType".

getJBoolean	back to summary
public boolean getJBoolean() throws UnmappedAddressException, UnalignedAddressException, WrongTypeException These accessors require that the field be static; otherwise, a WrongTypeException will be thrown. Note that type checking is not performed by these accessors in order to allow manual type coercion of field data. For better protection when accessing primitive fields, use the get(Type)Field accessors in Type.java. NOTE that the Address passed in to these routines may, in fact, be an OopHandle. Specifically, in a reflective system, dereferencing operations applied to the OopHandle must be performed atomically with respect to GC. See @see CIntegerType for a description of why all C integer types are bundled into the category "CIntegerType".

getJBoolean

back to summary

public boolean getJBoolean() throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

These accessors require that the field be static; otherwise, a WrongTypeException will be thrown. Note that type checking is not performed by these accessors in order to allow manual type coercion of field data. For better protection when accessing primitive fields, use the get(Type)Field accessors in Type.java.

See @see CIntegerType for a description of why all C integer types are bundled into the category "CIntegerType".

getJByte	back to summary
public byte getJByte(Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getJByte	back to summary
public byte getJByte() throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getJChar	back to summary
public char getJChar(Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getJChar	back to summary
public char getJChar() throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getJDouble	back to summary
public double getJDouble(Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getJDouble	back to summary
public double getJDouble() throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getJFloat	back to summary
public float getJFloat(Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getJFloat	back to summary
public float getJFloat() throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getJInt	back to summary
public int getJInt(Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getJInt	back to summary
public int getJInt() throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getJLong	back to summary
public long getJLong(Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getJLong	back to summary
public long getJLong() throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getJShort	back to summary
public short getJShort(Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getJShort	back to summary
public short getJShort() throws UnmappedAddressException, UnalignedAddressException, WrongTypeException

getName	back to summary
public String getName() Get the name of this field

getNarrowOopHandle	back to summary
public OopHandle getNarrowOopHandle(Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException, NotInHeapException

getNarrowOopHandle	back to summary
public OopHandle getNarrowOopHandle() throws UnmappedAddressException, UnalignedAddressException, NotInHeapException

getOffset	back to summary
public long getOffset() throws WrongTypeException The offset of this field, in bytes, in its containing data structure, if nonstatic. If this is a static field, throws a WrongTypeException.

getOopHandle	back to summary
public OopHandle getOopHandle(Address addr) throws UnmappedAddressException, UnalignedAddressException, WrongTypeException, NotInHeapException

getOopHandle	back to summary
public OopHandle getOopHandle() throws UnmappedAddressException, UnalignedAddressException, NotInHeapException

getSize	back to summary
public long getSize() Get the size, in bytes, of this field. Used for manual data structure traversal where necessary.

getStaticFieldAddress	back to summary
public Address getStaticFieldAddress() throws WrongTypeException The address of this field, if it is a static field. If this is a nonstatic field, throws a WrongTypeException.

getType	back to summary
public Type getType() Get the type of this field

isStatic	back to summary
public boolean isStatic() Is this a static field?

public Interface Field

Method Summary

Method Detail