DirectMethodHandleDesc interface in Java

java.lang.constant.DirectMethodHandleDesc

A nominal descriptor for a direct MethodHandle. A DirectMethodHandleDesc corresponds to a Constant_MethodHandle_info entry in the constant pool of a class file.

Declaration

public interface DirectMethodHandleDesc extends MethodHandleDesc {

    enum Kind {

        STATIC(REF_invokeStatic),

        INTERFACE_STATIC(REF_invokeStatic, true),

        VIRTUAL(REF_invokeVirtual),

        INTERFACE_VIRTUAL(REF_invokeInterface, true),

        SPECIAL(REF_invokeSpecial),

        INTERFACE_SPECIAL(REF_invokeSpecial, true),

        CONSTRUCTOR(REF_newInvokeSpecial),

        GETTER(REF_getField),

        SETTER(REF_putField),

        STATIC_GETTER(REF_getStatic),

        STATIC_SETTER(REF_putStatic);

        public final int refKind;

        public final boolean isInterface;

        Kind(int refKind) {
            this(refKind, false);
        }

        Kind(int refKind, boolean isInterface) {
            this.refKind = refKind;
            this.isInterface = isInterface;
        }

        public static Kind valueOf(int refKind) {
            return valueOf(refKind, false);
        }

        public static Kind valueOf(int refKind, boolean isInterface) {
            int i = tableIndex(refKind, isInterface);
            if (i >= 0 && i < TABLE.length) {
                Kind kind = TABLE[i];
                if (kind == null) {
                    throw new IllegalArgumentException(String.format("refKind=%d", refKind));
                }
                if (kind.refKind == refKind && kind.isInterface == isInterface) {
                    return kind;
                }
            }
            throw new IllegalArgumentException(String.format("refKind=%d", refKind));
        }

        private static int tableIndex(int refKind, boolean isInterface) {
            if (refKind < 0)
                return refKind;
            return (refKind * 2) + (isInterface ? 1 : 0);
        }

        private static final @Stable Kind[] TABLE;

        static {
            // Pack the static table.
            int max = 0;
            for (Kind k : values())
                max = Math.max(max, tableIndex(k.refKind, true));

            TABLE = new Kind[max + 1];
            for (Kind kind : values()) {
                int i = tableIndex(kind.refKind, kind.isInterface);
                if (i >= TABLE.length || TABLE[i] != null)
                    throw new AssertionError("TABLE entry for " + kind);
                TABLE[i] = kind;
            }
            int ii = tableIndex(REF_invokeInterface, false);
            if (TABLE[ii] != null)
                throw new AssertionError("TABLE entry for (invokeInterface, false) used by " + TABLE[ii]);
            TABLE[ii] = INTERFACE_VIRTUAL;

            for (Kind kind : values()) {
                if (!kind.isInterface) {

                    int i = tableIndex(kind.refKind, true);
                    if (TABLE[i] == null) {
                        // There is not a specific Kind for interfaces
                        if (kind == VIRTUAL)
                            kind = INTERFACE_VIRTUAL;
                        if (TABLE[i] == null)
                            TABLE[i] = kind;
                    }
                }
            }
        }

        boolean isVirtualMethod() {
            switch (this) {
            case VIRTUAL:
            case SPECIAL:
            case INTERFACE_VIRTUAL:
            case INTERFACE_SPECIAL:
                return true;
            default:
                return false;
            }
        }
    }

    Kind kind();

    int refKind();

    boolean isOwnerInterface();

    ClassDesc owner();

    String methodName();

    String lookupDescriptor();
}

Methods

1. Kind

java.lang.constant.DirectMethodHandleDesc.Kind

Kinds of method handle that can be described with DirectMethodHandleDesc.

2. valueOf(int refKind)

Kind java.lang.constant.DirectMethodHandleDesc.Kind.valueOf(int refKind)

This method takes one argument. This method returns the enumeration member with the given refKind field.

Parameters: One parameter is required for this method.

refKind: refKind of desired member.

Returns: the matching enumeration member.

Throws:

1. IllegalArgumentException - if there is no such member

3. valueOf(int refKind, boolean isInterface)

Kind java.lang.constant.DirectMethodHandleDesc.Kind.valueOf(int refKind, boolean isInterface)

This method takes two arguments. This method returns the enumeration member with the given refKind and isInterface arguments.

Parameters: Two parameters are required for this method.

refKind: refKind of the desired member.

isInterface: whether the desired member is for interface methods.

Returns: the matching enumeration member.

Throws:

1. IllegalArgumentException - if there is no such member

4. isVirtualMethod()

boolean java.lang.constant.DirectMethodHandleDesc.Kind.isVirtualMethod()

Does this Kind correspond to a virtual method invocation?

Returns: if this Kind corresponds to a virtual method invocation.

5. kind()

Kind java.lang.constant.DirectMethodHandleDesc.kind()

This method returns the kind of method handle described by this nominal descriptor.

Returns: the Kind

6. refKind()

int java.lang.constant.DirectMethodHandleDesc.refKind()

This method returns the refKind of the method handle described by this nominal reference, as defined by MethodHandleInfo.

Returns: the reference kind.

7. isOwnerInterface()

boolean java.lang.constant.DirectMethodHandleDesc.isOwnerInterface()

This method indicates if the method is declared by an interface

Returns: true if the method is declared by an interface

8. owner()

ClassDesc java.lang.constant.DirectMethodHandleDesc.owner()

This method returns a ClassDesc describing the class declaring the method or field described by this nominal descriptor.

Returns: the class declaring the method or field.

9. methodName()

String java.lang.constant.DirectMethodHandleDesc.methodName()

This method returns the name of the method or field described by this nominal descriptor. For constructors, returns the reserved name "<init>".

Returns: the name of the method or field.

10. lookupDescriptor()

String java.lang.constant.DirectMethodHandleDesc.lookupDescriptor()

This method returns the lookup descriptor of the method handle described by this descriptor, after adjusting for the invocation mode.

Some other classes/interfaces of java.lang.constant

MethodTypeDesc: A nominal descriptor for a MethodType constant.

MethodHandleDesc: A nominal descriptor for a MethodHandle constant.

DynamicConstantDesc: A nominal descriptor for a dynamic constant.

DynamicCallSiteDesc: A nominal descriptor for an invoke dynamic call site.

DirectMethodHandleDesc: A nominal descriptor for a direct MethodHandle. A DirectMethodHandleDesc corresponds to a Constant_MethodHandle_info entry in the constant pool of a class file.

ConstantDescs: Predefined values of nominal descriptors for common constants, including descriptors for primitive class types and other common platform types, and descriptors for method handles for standard bootstrap methods.

ConstantDesc: A nominal descriptor for a loadable constant value. Such a descriptor can be resolved via ConstantDesc.resolveConstantDesc(MethodHandles.Lookup) to yield the constant value itself.

Constable: Represents a type that is constable. A constable type is one whose values are constants that can be represented in the constant pool of a Java class file.

ClassDesc: A nominal descriptor for a Class constant.