public abstract Class MethodVisitor

The method visitor to which this visitor must delegate method calls. May be null.

Returns:MethodVisitor

the method visitor to which this visitor must delegate method calls, or null.

Visits the number of method parameters that can have annotations. By default (i.e. when this method is not called), all the method parameters defined by the method descriptor can have annotations.

Parameters

parameterCount:int

the number of method parameters than can have annotations. This number must be less or equal than the number of parameter types in the method descriptor. It can be strictly less when a method has synthetic parameters and when these parameters are ignored when computing parameter indices for the purpose of parameter annotations (see https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.18).

visible:boolean

true to define the number of method parameters that can have annotations visible at runtime, false to define the number of method parameters that can have annotations invisible at runtime.

Visits an annotation of this method.

Parameters

descriptor:String

the class descriptor of the annotation class.

visible:boolean

true if the annotation is visible at runtime.

Returns:AnnotationVisitor

a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.

Visits the default value of this annotation interface method.

Returns:AnnotationVisitor

a visitor to the visit the actual default value of this annotation interface method, or null if this visitor is not interested in visiting this default value. The 'name' parameters passed to the methods of this annotation visitor are ignored. Moreover, exactly one visit method must be called on this annotation visitor, followed by visitEnd.

Visits a non standard attribute of this method.

Parameters

attribute:Attribute

an attribute.

Starts the visit of the method's code, if any (i.e. non abstract method).

Visits the end of the method. This method, which is the last one to be called, is used to inform the visitor that all the annotations and attributes of the method have been visited.

Visits a field instruction. A field instruction is an instruction that loads or stores the value of a field of an object.

Parameters

opcode:int

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

owner:String

the internal name of the field's owner class (see Type#getInternalName()).

name:String

the field's name.

descriptor:String

the field's descriptor (see Type).

Visits the current state of the local variables and operand stack elements. This method must(*) be called just before any instruction i that follows an unconditional branch instruction such as GOTO or THROW, that is the target of a jump instruction, or that starts an exception handler block. The visited types must describe the values of the local variables and of the operand stack elements just before i is executed.

(*) this is mandatory only for classes whose version is greater than or equal to Opcodes#V1_6.

The frames of a method must be given either in expanded form, or in compressed form (all frames must use the same format, i.e. you must not mix expanded and compressed frames within a single method):

• In expanded form, all frames must have the F_NEW type.
• In compressed form, frames are basically "deltas" from the state of the previous frame:
  • Opcodes#F_SAME representing frame with exactly the same locals as the previous frame and with the empty stack.
  • Opcodes#F_SAME1 representing frame with exactly the same locals as the previous frame and with single value on the stack ( numStack is 1 and stack[0] contains value for the type of the stack item).
  • Opcodes#F_APPEND representing frame with current locals are the same as the locals in the previous frame, except that additional locals are defined ( numLocal is 1, 2 or 3 and local elements contains values representing added types).
  • Opcodes#F_CHOP representing frame with current locals are the same as the locals in the previous frame, except that the last 1-3 locals are absent and with the empty stack (numLocal is 1, 2 or 3).
  • Opcodes#F_FULL representing complete frame data.

Parameters

type:int

the type of this stack map frame. Must be Opcodes#F_NEW for expanded frames, or Opcodes#F_FULL, Opcodes#F_APPEND, Opcodes#F_CHOP, Opcodes#F_SAME or Opcodes#F_APPEND, Opcodes#F_SAME1 for compressed frames.

numLocal:int

the number of local variables in the visited frame. Long and double values count for one variable.

local:Object[]

the local variable types in this frame. This array must not be modified. Primitive types are represented by Opcodes#TOP, Opcodes#INTEGER, Opcodes#FLOAT, Opcodes#LONG, Opcodes#DOUBLE, Opcodes#NULL or Opcodes#UNINITIALIZED_THIS (long and double are represented by a single element). Reference types are represented by String objects (representing internal names, see Type#getInternalName()), and uninitialized types by Label objects (this label designates the NEW instruction that created this uninitialized value).

numStack:int

the number of operand stack elements in the visited frame. Long and double values count for one stack element.

stack:Object[]

the operand stack types in this frame. This array must not be modified. Its content has the same format as the "local" array.

Exceptions

IllegalStateException:

if a frame is visited just after another one, without any instruction between the two (unless this frame is a Opcodes#F_SAME frame, in which case it is silently ignored).

Visits an IINC instruction.

Parameters

varIndex:int

index of the local variable to be incremented.

increment:int

amount to increment the local variable by.

Visits a zero operand instruction.

Parameters

opcode:int

the opcode of the instruction to be visited. This opcode is either NOP, ACONST_NULL, ICONST_M1, ICONST_0, ICONST_1, ICONST_2, ICONST_3, ICONST_4, ICONST_5, LCONST_0, LCONST_1, FCONST_0, FCONST_1, FCONST_2, DCONST_0, DCONST_1, IALOAD, LALOAD, FALOAD, DALOAD, AALOAD, BALOAD, CALOAD, SALOAD, IASTORE, LASTORE, FASTORE, DASTORE, AASTORE, BASTORE, CASTORE, SASTORE, POP, POP2, DUP, DUP_X1, DUP_X2, DUP2, DUP2_X1, DUP2_X2, SWAP, IADD, LADD, FADD, DADD, ISUB, LSUB, FSUB, DSUB, IMUL, LMUL, FMUL, DMUL, IDIV, LDIV, FDIV, DDIV, IREM, LREM, FREM, DREM, INEG, LNEG, FNEG, DNEG, ISHL, LSHL, ISHR, LSHR, IUSHR, LUSHR, IAND, LAND, IOR, LOR, IXOR, LXOR, I2L, I2F, I2D, L2I, L2F, L2D, F2I, F2L, F2D, D2I, D2L, D2F, I2B, I2C, I2S, LCMP, FCMPL, FCMPG, DCMPL, DCMPG, IRETURN, LRETURN, FRETURN, DRETURN, ARETURN, RETURN, ARRAYLENGTH, ATHROW, MONITORENTER, or MONITOREXIT.

Visits an annotation on an instruction. This method must be called just after the annotated instruction. It can be called several times for the same instruction.

Parameters

typeRef:int

a reference to the annotated type. The sort of this type reference must be TypeReference#INSTANCEOF, TypeReference#NEW, TypeReference#CONSTRUCTOR_REFERENCE, TypeReference#METHOD_REFERENCE, TypeReference#CAST, TypeReference#CONSTRUCTOR_INVOCATION_TYPE_ARGUMENT, TypeReference#METHOD_INVOCATION_TYPE_ARGUMENT, TypeReference#CONSTRUCTOR_REFERENCE_TYPE_ARGUMENT, or TypeReference#METHOD_REFERENCE_TYPE_ARGUMENT. See TypeReference.

typePath:TypePath

the path to the annotated type argument, wildcard bound, array element type, or static inner type within 'typeRef'. May be null if the annotation targets 'typeRef' as a whole.

descriptor:String

the class descriptor of the annotation class.

visible:boolean

true if the annotation is visible at runtime.

Returns:AnnotationVisitor

a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.

Visits an instruction with a single int operand.

Parameters

opcode:int

the opcode of the instruction to be visited. This opcode is either BIPUSH, SIPUSH or NEWARRAY.

operand:int

the operand of the instruction to be visited.
When opcode is BIPUSH, operand value should be between Byte.MIN_VALUE and Byte.MAX_VALUE.
When opcode is SIPUSH, operand value should be between Short.MIN_VALUE and Short.MAX_VALUE.
When opcode is NEWARRAY, operand value should be one of Opcodes#T_BOOLEAN, Opcodes#T_CHAR, Opcodes#T_FLOAT, Opcodes#T_DOUBLE, Opcodes#T_BYTE, Opcodes#T_SHORT, Opcodes#T_INT or Opcodes#T_LONG.

Visits an invokedynamic instruction.

Parameters

name:String

the method's name.

descriptor:String

the method's descriptor (see Type).

bootstrapMethodHandle:Handle

the bootstrap method.

bootstrapMethodArguments:Object[]

the bootstrap method constant arguments. Each argument must be an Integer, Float, Long, Double, String, Type, Handle or ConstantDynamic value. This method is allowed to modify the content of the array so a caller should expect that this array may change.

Visits a jump instruction. A jump instruction is an instruction that may jump to another instruction.

Parameters

opcode:int

the opcode of the type instruction to be visited. This opcode is either IFEQ, IFNE, IFLT, IFGE, IFGT, IFLE, IF_ICMPEQ, IF_ICMPNE, IF_ICMPLT, IF_ICMPGE, IF_ICMPGT, IF_ICMPLE, IF_ACMPEQ, IF_ACMPNE, GOTO, JSR, IFNULL or IFNONNULL.

label:Label

the operand of the instruction to be visited. This operand is a label that designates the instruction to which the jump instruction may jump.

Visits a label. A label designates the instruction that will be visited just after it.

Parameters

label:Label

a Label object.

Visits a LDC instruction. Note that new constant types may be added in future versions of the Java Virtual Machine. To easily detect new constant types, implementations of this method should check for unexpected constant types, like this:

if (cst instanceof Integer) {
    // ...
} else if (cst instanceof Float) {
    // ...
} else if (cst instanceof Long) {
    // ...
} else if (cst instanceof Double) {
    // ...
} else if (cst instanceof String) {
    // ...
} else if (cst instanceof Type) {
    int sort = ((Type) cst).getSort();
    if (sort == Type.OBJECT) {
        // ...
    } else if (sort == Type.ARRAY) {
        // ...
    } else if (sort == Type.METHOD) {
        // ...
    } else {
        // throw an exception
    }
} else if (cst instanceof Handle) {
    // ...
} else if (cst instanceof ConstantDynamic) {
    // ...
} else {
    // throw an exception
}

Parameters

value:Object

the constant to be loaded on the stack. This parameter must be a non null Integer, a Float, a Long, a Double, a String, a Type of OBJECT or ARRAY sort for .class constants, for classes whose version is 49, a Type of METHOD sort for MethodType, a Handle for MethodHandle constants, for classes whose version is 51 or a ConstantDynamic for a constant dynamic for classes whose version is 55.

Visits a line number declaration.

Parameters

line:int

a line number. This number refers to the source file from which the class was compiled.

start:Label

the first instruction corresponding to this line number.

Exceptions

IllegalArgumentException:

if start has not already been visited by this visitor (by the visitLabel method).

Visits a local variable declaration.

Parameters

name:String

the name of a local variable.

descriptor:String

the type descriptor of this local variable.

signature:String

the type signature of this local variable. May be null if the local variable type does not use generic types.

start:Label

the first instruction corresponding to the scope of this local variable (inclusive).

end:Label

the last instruction corresponding to the scope of this local variable (exclusive).

index:int

the local variable's index.

Exceptions

IllegalArgumentException:

if one of the labels has not already been visited by this visitor (by the visitLabel method).

Visits an annotation on a local variable type.

Parameters

typeRef:int

a reference to the annotated type. The sort of this type reference must be TypeReference#LOCAL_VARIABLE or TypeReference#RESOURCE_VARIABLE. See TypeReference.

typePath:TypePath

the path to the annotated type argument, wildcard bound, array element type, or static inner type within 'typeRef'. May be null if the annotation targets 'typeRef' as a whole.

start:Label[]

the fist instructions corresponding to the continuous ranges that make the scope of this local variable (inclusive).

end:Label[]

the last instructions corresponding to the continuous ranges that make the scope of this local variable (exclusive). This array must have the same size as the 'start' array.

index:int[]

the local variable's index in each range. This array must have the same size as the 'start' array.

descriptor:String

the class descriptor of the annotation class.

visible:boolean

true if the annotation is visible at runtime.

Returns:AnnotationVisitor

a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.

Visits a LOOKUPSWITCH instruction.

Parameters

dflt:Label

beginning of the default handler block.

keys:int[]

the values of the keys.

labels:Label[]

beginnings of the handler blocks. labels[i] is the beginning of the handler block for the keys[i] key.

Visits the maximum stack size and the maximum number of local variables of the method.

Parameters

maxStack:int

maximum stack size of the method.

maxLocals:int

maximum number of local variables for the method.

Visits a method instruction. A method instruction is an instruction that invokes a method.

Parameters

opcode:int

the opcode of the type instruction to be visited. This opcode is either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or INVOKEINTERFACE.

owner:String

the internal name of the method's owner class (see Type#getInternalName()).

name:String

the method's name.

descriptor:String

the method's descriptor (see Type).

Annotations

@Deprecated

Visits a method instruction. A method instruction is an instruction that invokes a method.

Parameters

opcode:int

the opcode of the type instruction to be visited. This opcode is either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or INVOKEINTERFACE.

owner:String

the internal name of the method's owner class (see Type#getInternalName()).

name:String

the method's name.

descriptor:String

the method's descriptor (see Type).

isInterface:boolean

if the method's owner class is an interface.

Visits a MULTIANEWARRAY instruction.

Parameters

descriptor:String

an array type descriptor (see Type).

numDimensions:int

the number of dimensions of the array to allocate.

Visits a parameter of this method.

Parameters

name:String

parameter name or null if none is provided.

access:int

the parameter's access flags, only ACC_FINAL, ACC_SYNTHETIC or/and ACC_MANDATED are allowed (see Opcodes).

Visits an annotation of a parameter this method.

Parameters

parameter:int

the parameter index. This index must be strictly smaller than the number of parameters in the method descriptor, and strictly smaller than the parameter count specified in visitAnnotableParameterCount.

Important Note

a parameter index i is not required to correspond to the i'th parameter descriptor in the method descriptor, in particular in case of synthetic parameters (see https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-4.html#jvms-4.7.18).

descriptor:String

the class descriptor of the annotation class.

visible:boolean

true if the annotation is visible at runtime.

Returns:AnnotationVisitor

a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.

Visits a TABLESWITCH instruction.

Parameters

min:int

the minimum key value.

max:int

the maximum key value.

dflt:Label

beginning of the default handler block.

labels:Label[]

beginnings of the handler blocks. labels[i] is the beginning of the handler block for the min + i key.

Visits an annotation on an exception handler type. This method must be called after the visitTryCatchBlock for the annotated exception handler. It can be called several times for the same exception handler.

Parameters

typeRef:int

a reference to the annotated type. The sort of this type reference must be TypeReference#EXCEPTION_PARAMETER. See TypeReference.

typePath:TypePath

the path to the annotated type argument, wildcard bound, array element type, or static inner type within 'typeRef'. May be null if the annotation targets 'typeRef' as a whole.

descriptor:String

the class descriptor of the annotation class.

visible:boolean

true if the annotation is visible at runtime.

Returns:AnnotationVisitor

a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.

Visits a try catch block.

Parameters

start:Label

the beginning of the exception handler's scope (inclusive).

end:Label

the end of the exception handler's scope (exclusive).

handler:Label

the beginning of the exception handler's code.

type:String

the internal name of the type of exceptions handled by the handler (see Type#getInternalName()), or null to catch any exceptions (for "finally" blocks).

Exceptions

IllegalArgumentException:

if one of the labels has already been visited by this visitor (by the visitLabel method).

Visits an annotation on a type in the method signature.

Parameters

typeRef:int

a reference to the annotated type. The sort of this type reference must be TypeReference#METHOD_TYPE_PARAMETER, TypeReference#METHOD_TYPE_PARAMETER_BOUND, TypeReference#METHOD_RETURN, TypeReference#METHOD_RECEIVER, TypeReference#METHOD_FORMAL_PARAMETER or TypeReference#THROWS. See TypeReference.

typePath:TypePath

the path to the annotated type argument, wildcard bound, array element type, or static inner type within 'typeRef'. May be null if the annotation targets 'typeRef' as a whole.

descriptor:String

the class descriptor of the annotation class.

visible:boolean

true if the annotation is visible at runtime.

Returns:AnnotationVisitor

a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.

Visits a type instruction. A type instruction is an instruction that takes the internal name of a class as parameter (see Type#getInternalName()).

Parameters

opcode:int

the opcode of the type instruction to be visited. This opcode is either NEW, ANEWARRAY, CHECKCAST or INSTANCEOF.

type:String

the operand of the instruction to be visited. This operand must be the internal name of an object or array class (see Type#getInternalName()).

Visits a local variable instruction. A local variable instruction is an instruction that loads or stores the value of a local variable.

Parameters

opcode:int

the opcode of the local variable instruction to be visited. This opcode is either ILOAD, LLOAD, FLOAD, DLOAD, ALOAD, ISTORE, LSTORE, FSTORE, DSTORE, ASTORE or RET.

varIndex:int

the operand of the instruction to be visited. This operand is the index of a local variable.