Package xyz.cofe.trambda.bc.mth

Class MFieldInsn

  • All Implemented Interfaces:
    Serializable, xyz.cofe.collection.ImTree<ByteCode>, xyz.cofe.collection.ImTreeWalk<ByteCode>, ByteCode, MethodByteCode, MethodWriter
    public class MFieldInsn
extends MAbstractBC
implements MethodWriter
    Доступ к полю объекта

    the opcode of the type instruction to be visited. This opcode is either GETSTATIC, PUTSTATIC, GETFIELD or PUTFIELD.

    getstatic

    Operation

    Get static field from class

    Format

     getstatic
 indexbyte1
 indexbyte2

    Forms

    getstatic = 178 (0xb2)

    Operand Stack

     ..., →
 ..., value

    Description

    The unsigned indexbyte1 and indexbyte2 are used to construct an index into the run-time constant pool of the current class (§2.6), where the value of the index is (indexbyte1 << 8) | indexbyte2. The run-time constant pool item at that index must be a symbolic reference to a field (§5.1), which gives the name and descriptor of the field as well as a symbolic reference to the class or interface in which the field is to be found. The referenced field is resolved (§5.4.3.2). On successful resolution of the field, the class or interface that declared the resolved field is initialized (§5.5) if that class or interface has not already been initialized. The value of the class or interface field is fetched and pushed onto the operand stack.

    Linking Exceptions

    During resolution of the symbolic reference to the class or interface field, any of the exceptions pertaining to field resolution (§5.4.3.2) can be thrown. Otherwise, if the resolved field is not a static (class) field or an interface field, getstatic throws an IncompatibleClassChangeError.

    Run-time Exception

    Otherwise, if execution of this getstatic instruction causes initialization of the referenced class or interface, getstatic may throw an Error as detailed in §5.5.
    putstatic

    Operation

    Set static field in class

    Format

     putstatic
 indexbyte1
 indexbyte2

    Forms

    putstatic = 179 (0xb3)

    Operand Stack

     ..., value →
 ...

    Description

    The unsigned indexbyte1 and indexbyte2 are used to construct an index into the run-time constant pool of the current class (§2.6), where the value of the index is (indexbyte1 << 8) | indexbyte2. The run-time constant pool item at that index must be a symbolic reference to a field (§5.1), which gives the name and descriptor of the field as well as a symbolic reference to the class or interface in which the field is to be found. The referenced field is resolved (§5.4.3.2).

    On successful resolution of the field, the class or interface that declared the resolved field is initialized (§5.5) if that class or interface has not already been initialized.

    The type of a value stored by a putstatic instruction must be compatible with the descriptor of the referenced field (§4.3.2). If the field descriptor type is boolean, byte, char, short, or int, then the value must be an int. If the field descriptor type is float, long, or double, then the value must be a float, long, or double, respectively. If the field descriptor type is a reference type, then the value must be of a type that is assignment compatible (JLS §5.2) with the field descriptor type. If the field is final, it must be declared in the current class, and the instruction must occur in the <clinit> method of the current class (§2.9).

    The value is popped from the operand stack and undergoes value set conversion (§2.8.3), resulting in value'. The class field is set to value'.

    Linking Exceptions

    During resolution of the symbolic reference to the class or interface field, any of the exceptions pertaining to field resolution (§5.4.3.2) can be thrown.

    Otherwise, if the resolved field is not a static (class) field or an interface field, putstatic throws an IncompatibleClassChangeError.

    Otherwise, if the field is final, it must be declared in the current class, and the instruction must occur in the <clinit> method of the current class. Otherwise, an IllegalAccessError is thrown.

    Run-time Exception

    Otherwise, if execution of this putstatic instruction causes initialization of the referenced class or interface, putstatic may throw an Error as detailed in §5.5.

    Notes

    A putstatic instruction may be used only to set the value of an interface field on the initialization of that field. Interface fields may be assigned to only once, on execution of an interface variable initialization expression when the interface is initialized (§5.5, JLS §9.3.1).
    getfield

    Operation

    Fetch field from object

    Format

     getfield
 indexbyte1
 indexbyte2

    Forms

    getfield = 180 (0xb4)

    Operand Stack

     ..., objectref →
 ..., value

    Description

    The objectref, which must be of type reference, is popped from the operand stack. The unsigned indexbyte1 and indexbyte2 are used to construct an index into the run-time constant pool of the current class (§2.6), where the value of the index is (indexbyte1 << 8) | indexbyte2. The run-time constant pool item at that index must be a symbolic reference to a field (§5.1), which gives the name and descriptor of the field as well as a symbolic reference to the class in which the field is to be found. The referenced field is resolved (§5.4.3.2). The value of the referenced field in objectref is fetched and pushed onto the operand stack. The type of objectref must not be an array type. If the field is protected, and it is a member of a superclass of the current class, and the field is not declared in the same run-time package (§5.3) as the current class, then the class of objectref must be either the current class or a subclass of the current class.

    Linking Exceptions

    During resolution of the symbolic reference to the field, any of the errors pertaining to field resolution (§5.4.3.2) can be thrown. Otherwise, if the resolved field is a static field, getfield throws an IncompatibleClassChangeError.

    Run-time Exception

    Otherwise, if objectref is null, the getfield instruction throws a NullPointerException.

    Notes

    The getfield instruction cannot be used to access the length field of an array. The arraylength instruction (§arraylength) is used instead.
    putfield

    Operation

    Set field in object

    Format

     putfield
 indexbyte1
 indexbyte2

    Forms

    putfield = 181 (0xb5)

    Operand Stack

     ..., objectref, value →
 ...

    Description

    The unsigned indexbyte1 and indexbyte2 are used to construct an index into the run-time constant pool of the current class (§2.6), where the value of the index is (indexbyte1 << 8) | indexbyte2. The run-time constant pool item at that index must be a symbolic reference to a field (§5.1), which gives the name and descriptor of the field as well as a symbolic reference to the class in which the field is to be found. The class of objectref must not be an array. If the field is protected, and it is a member of a superclass of the current class, and the field is not declared in the same run-time package (§5.3) as the current class, then the class of objectref must be either the current class or a subclass of the current class.

    The referenced field is resolved (§5.4.3.2). The type of a value stored by a putfield instruction must be compatible with the descriptor of the referenced field (§4.3.2). If the field descriptor type is boolean, byte, char, short, or int, then the value must be an int. If the field descriptor type is float, long, or double, then the value must be a float, long, or double, respectively. If the field descriptor type is a reference type, then the value must be of a type that is assignment compatible (JLS §5.2) with the field descriptor type. If the field is final, it must be declared in the current class, and the instruction must occur in an instance initialization method (<init>) of the current class (§2.9).

    The value and objectref are popped from the operand stack. The objectref must be of type reference. The value undergoes value set conversion (§2.8.3), resulting in value', and the referenced field in objectref is set to value'.

    Linking Exceptions

    During resolution of the symbolic reference to the field, any of the exceptions pertaining to field resolution (§5.4.3.2) can be thrown.

    Otherwise, if the resolved field is a static field, putfield throws an IncompatibleClassChangeError.

    Otherwise, if the field is final, it must be declared in the current class, and the instruction must occur in an instance initialization method (<init>) of the current class. Otherwise, an IllegalAccessError is thrown.

    Run-time Exception

    Otherwise, if objectref is null, the putfield instruction throws a NullPointerException.
    See Also:
    Serialized Form

    • Constructor Detail

      • MFieldInsn

        public MFieldInsn()
        Конструктор по умолчанию

      • MFieldInsn

        public MFieldInsn​(int opcode,
                  String owner,
                  String name,
                  String descriptor)

      • MFieldInsn

        public MFieldInsn​(MFieldInsn sample)
        Конструктор копирования
        Parameters:
        sample - образец