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public abstract class MethodVisitor
A visitor to visit a Java method. The methods of this class must be called in the following order: ( visitParameter )* [ visitAnnotationDefault ] ( visitAnnotation | visitAnnotableParameterCount | visitParameterAnnotation visitTypeAnnotation | visitAttribute )* [ visitCode ( visitFrame | visitXInsn | visitLabel | visitInsnAnnotation | visitTryCatchBlock | visitTryCatchAnnotation | visitLocalVariable | visitLocalVariableAnnotation | visitLineNumber )* visitMaxs ] visitEnd. In addition, the visitXInsn and visitLabel methods must be called in the sequential order of the bytecode instructions of the visited code, visitInsnAnnotation must be called after the annotated instruction, visitTryCatchBlock must be called before the labels passed as arguments have been visited, visitTryCatchBlockAnnotation must be called after the corresponding try catch block has been visited, and the visitLocalVariable, visitLocalVariableAnnotation and visitLineNumber methods must be called after the labels passed as arguments have been visited.
Fields
protected final int
The ASM API version implemented by this visitor.
protected MethodVisitor
The method visitor to which this visitor must delegate method calls.
Constructors
public
MethodVisitor(int api)
Constructs a new MethodVisitor.
public
MethodVisitor(int api, MethodVisitor methodVisitor)
Constructs a new MethodVisitor.
Methods
public void
visitAnnotableParameterCount(int parameterCount, boolean visible)
Visits the number of method parameters that can have annotations.
public AnnotationVisitor
visitAnnotation(String descriptor, boolean visible)
Visits an annotation of this method.
public AnnotationVisitor
Visits the default value of this annotation interface method.
public void
Visits a non standard attribute of this method.
public void
Starts the visit of the method's code, if any (i.e.
public void
Visits the end of the method.
public void
visitFieldInsn(int opcode, String owner, String name, String descriptor)
Visits a field instruction.
public void
visitFrame(int type, int numLocal, Object[] local, int numStack, Object[] stack)
Visits the current state of the local variables and operand stack elements.
public void
visitIincInsn(int var, int increment)
Visits an IINC instruction.
public void
visitInsn(int opcode)
Visits a zero operand instruction.
public AnnotationVisitor
visitInsnAnnotation(int typeRef, TypePath typePath, String descriptor, boolean visible)
Visits an annotation on an instruction.
public void
visitIntInsn(int opcode, int operand)
Visits an instruction with a single int operand.
public void
visitInvokeDynamicInsn(String name, String descriptor, Handle bootstrapMethodHandle, Object... bootstrapMethodArguments)
Visits an invokedynamic instruction.
public void
visitJumpInsn(int opcode, Label label)
Visits a jump instruction.
public void
Visits a label.
public void
Visits a LDC instruction.
public void
visitLineNumber(int line, Label start)
Visits a line number declaration.
public void
visitLocalVariable(String name, String descriptor, String signature, Label start, Label end, int index)
Visits a local variable declaration.
public AnnotationVisitor
visitLocalVariableAnnotation(int typeRef, TypePath typePath, Label[] start, Label[] end, int[] index, String descriptor, boolean visible)
Visits an annotation on a local variable type.
public void
visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels)
Visits a LOOKUPSWITCH instruction.
public void
visitMaxs(int maxStack, int maxLocals)
Visits the maximum stack size and the maximum number of local variables of the method.
public void
visitMethodInsn(int opcode, String owner, String name, String descriptor)
public void
visitMethodInsn(int opcode, String owner, String name, String descriptor, boolean isInterface)
Visits a method instruction.
public void
visitMultiANewArrayInsn(String descriptor, int numDimensions)
Visits a MULTIANEWARRAY instruction.
public void
visitParameter(String name, int access)
Visits a parameter of this method.
public AnnotationVisitor
visitParameterAnnotation(int parameter, String descriptor, boolean visible)
Visits an annotation of a parameter this method.
public void
visitTableSwitchInsn(int min, int max, Label dflt, Label... labels)
Visits a TABLESWITCH instruction.
public AnnotationVisitor
visitTryCatchAnnotation(int typeRef, TypePath typePath, String descriptor, boolean visible)
Visits an annotation on an exception handler type.
public void
visitTryCatchBlock(Label start, Label end, Label handler, String type)
Visits a try catch block.
public AnnotationVisitor
visitTypeAnnotation(int typeRef, TypePath typePath, String descriptor, boolean visible)
Visits an annotation on a type in the method signature.
public void
visitTypeInsn(int opcode, String type)
Visits a type instruction.
public void
visitVarInsn(int opcode, int var)
Visits a local variable instruction.
protected final int api
The ASM API version implemented by this visitor. The value of this field must be one of Opcodes.ASM4, Opcodes.ASM5, Opcodes.ASM6 or Opcodes.ASM7.
protected MethodVisitor mv
The method visitor to which this visitor must delegate method calls. May be null.
public MethodVisitor(int api)
Constructs a new MethodVisitor.
apithe ASM API version implemented by this visitor. Must be one of Opcodes.ASM4, Opcodes.ASM5, Opcodes.ASM6 or Opcodes.ASM7.
public MethodVisitor(int api, MethodVisitor methodVisitor)
Constructs a new MethodVisitor.
apithe ASM API version implemented by this visitor. Must be one of Opcodes.ASM4, Opcodes.ASM5, Opcodes.ASM6 or Opcodes.ASM7.
methodVisitorthe method visitor to which this visitor must delegate method calls. May be null.
public void visitAnnotableParameterCount(int parameterCount, boolean visible)
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.
parameterCountthe 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).
visibletrue 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.
public AnnotationVisitor visitAnnotation(String descriptor, boolean visible)
Visits an annotation of this method.
descriptorthe class descriptor of the annotation class.
visibletrue if the annotation is visible at runtime.
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.
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, exacly one visit method must be called on this annotation visitor, followed by visitEnd.
public void visitAttribute(Attribute attribute)
Visits a non standard attribute of this method.
attributean attribute.
public void visitCode()
Starts the visit of the method's code, if any (i.e. non abstract method).
public void visitEnd()
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.
public void visitFieldInsn(int opcode, String owner, String name, String descriptor)
Visits a field instruction. A field instruction is an instruction that loads or stores the value of a field of an object.
opcodethe opcode of the type instruction to be visited. This opcode is either GETSTATIC, PUTSTATIC, GETFIELD or PUTFIELD.
ownerthe internal name of the field's owner class (see Type.getInternalName()).
namethe field's name.
descriptorthe field's descriptor (see Type).
public void visitFrame(int type, int numLocal, Object[] local, int numStack, Object[] stack)
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.

In both cases the first frame, corresponding to the method's parameters and access flags, is implicit and must not be visited. Also, it is illegal to visit two or more frames for the same code location (i.e., at least one instruction must be visited between two calls to visitFrame).
typethe 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.
numLocalthe number of local variables in the visited frame.
localthe 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), and uninitialized types by Label objects (this label designates the NEW instruction that created this uninitialized value).
numStackthe number of operand stack elements in the visited frame.
stackthe operand stack types in this frame. This array must not be modified. Its content has the same format as the "local" array.
public void visitIincInsn(int var, int increment)
Visits an IINC instruction.
varindex of the local variable to be incremented.
incrementamount to increment the local variable by.
public void visitInsn(int opcode)
Visits a zero operand instruction.
opcodethe 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.
public AnnotationVisitor visitInsnAnnotation(int typeRef, TypePath typePath, String descriptor, boolean visible)
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.
typePaththe 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.
descriptorthe class descriptor of the annotation class.
visibletrue if the annotation is visible at runtime.
a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.
public void visitIntInsn(int opcode, int operand)
Visits an instruction with a single int operand.
opcodethe opcode of the instruction to be visited. This opcode is either BIPUSH, SIPUSH or NEWARRAY.
operandthe 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.
public void visitInvokeDynamicInsn(String name, String descriptor, Handle bootstrapMethodHandle, Object... bootstrapMethodArguments)
Visits an invokedynamic instruction.
namethe method's name.
descriptorthe method's descriptor (see Type).
bootstrapMethodHandlethe bootstrap method.
bootstrapMethodArgumentsthe 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.
public void visitJumpInsn(int opcode, Label label)
Visits a jump instruction. A jump instruction is an instruction that may jump to another instruction.
opcodethe 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.
labelthe operand of the instruction to be visited. This operand is a label that designates the instruction to which the jump instruction may jump.
public void visitLabel(Label label)
Visits a label. A label designates the instruction that will be visited just after it.
labela Label object.
public void visitLdcInsn(Object value)
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
 }
 
valuethe 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.
public void visitLineNumber(int line, Label start)
Visits a line number declaration.
linea line number. This number refers to the source file from which the class was compiled.
startthe first instruction corresponding to this line number.
public void visitLocalVariable(String name, String descriptor, String signature, Label start, Label end, int index)
Visits a local variable declaration.
namethe name of a local variable.
descriptorthe type descriptor of this local variable.
signaturethe type signature of this local variable. May be null if the local variable type does not use generic types.
startthe first instruction corresponding to the scope of this local variable (inclusive).
endthe last instruction corresponding to the scope of this local variable (exclusive).
indexthe local variable's index.
public AnnotationVisitor visitLocalVariableAnnotation(int typeRef, TypePath typePath, Label[] start, Label[] end, int[] index, String descriptor, boolean visible)
Visits an annotation on a local variable type.
typeRefa reference to the annotated type. The sort of this type reference must be TypeReference.LOCAL_VARIABLE or TypeReference.RESOURCE_VARIABLE. See TypeReference.
typePaththe 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.
startthe fist instructions corresponding to the continuous ranges that make the scope of this local variable (inclusive).
endthe 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.
indexthe local variable's index in each range. This array must have the same size as the 'start' array.
descriptorthe class descriptor of the annotation class.
visibletrue if the annotation is visible at runtime.
a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.
public void visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels)
Visits a LOOKUPSWITCH instruction.
dfltbeginning of the default handler block.
keysthe values of the keys.
labelsbeginnings of the handler blocks. labels[i] is the beginning of the handler block for the keys[i] key.
public void visitMaxs(int maxStack, int maxLocals)
Visits the maximum stack size and the maximum number of local variables of the method.
maxStackmaximum stack size of the method.
maxLocalsmaximum number of local variables for the method.
public void visitMethodInsn(int opcode, String owner, String name, String descriptor)
Visits a method instruction. A method instruction is an instruction that invokes a method.
opcodethe opcode of the type instruction to be visited. This opcode is either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or INVOKEINTERFACE.
ownerthe internal name of the method's owner class (see Type.getInternalName()).
namethe method's name.
descriptorthe method's descriptor (see Type).
public void visitMethodInsn(int opcode, String owner, String name, String descriptor, boolean isInterface)
Visits a method instruction. A method instruction is an instruction that invokes a method.
opcodethe opcode of the type instruction to be visited. This opcode is either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or INVOKEINTERFACE.
ownerthe internal name of the method's owner class (see Type.getInternalName()).
namethe method's name.
descriptorthe method's descriptor (see Type).
isInterfaceif the method's owner class is an interface.
public void visitMultiANewArrayInsn(String descriptor, int numDimensions)
Visits a MULTIANEWARRAY instruction.
descriptoran array type descriptor (see Type).
numDimensionsthe number of dimensions of the array to allocate.
public void visitParameter(String name, int access)
Visits a parameter of this method.
nameparameter name or null if none is provided.
accessthe parameter's access flags, only ACC_FINAL, ACC_SYNTHETIC or/and ACC_MANDATED are allowed (see Opcodes).
public AnnotationVisitor visitParameterAnnotation(int parameter, String descriptor, boolean visible)
Visits an annotation of a parameter this method.
parameterthe 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(int, boolean). 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).
descriptorthe class descriptor of the annotation class.
visibletrue if the annotation is visible at runtime.
a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.
public void visitTableSwitchInsn(int min, int max, Label dflt, Label... labels)
Visits a TABLESWITCH instruction.
minthe minimum key value.
maxthe maximum key value.
dfltbeginning of the default handler block.
labelsbeginnings of the handler blocks. labels[i] is the beginning of the handler block for the min + i key.
public AnnotationVisitor visitTryCatchAnnotation(int typeRef, TypePath typePath, String descriptor, boolean visible)
Visits an annotation on an exception handler type. This method must be called after the visitTryCatchBlock(Label, Label, Label, String) for the annotated exception handler. It can be called several times for the same exception handler.
typeRefa reference to the annotated type. The sort of this type reference must be TypeReference.EXCEPTION_PARAMETER. See TypeReference.
typePaththe 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.
descriptorthe class descriptor of the annotation class.
visibletrue if the annotation is visible at runtime.
a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.
public void visitTryCatchBlock(Label start, Label end, Label handler, String type)
Visits a try catch block.
startthe beginning of the exception handler's scope (inclusive).
endthe end of the exception handler's scope (exclusive).
handlerthe beginning of the exception handler's code.
typethe internal name of the type of exceptions handled by the handler, or null to catch any exceptions (for "finally" blocks).
public AnnotationVisitor visitTypeAnnotation(int typeRef, TypePath typePath, String descriptor, boolean visible)
Visits an annotation on a type in the method signature.
typePaththe 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.
descriptorthe class descriptor of the annotation class.
visibletrue if the annotation is visible at runtime.
a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.
public void visitTypeInsn(int opcode, String type)
Visits a type instruction. A type instruction is an instruction that takes the internal name of a class as parameter.
opcodethe opcode of the type instruction to be visited. This opcode is either NEW, ANEWARRAY, CHECKCAST or INSTANCEOF.
typethe operand of the instruction to be visited. This operand must be the internal name of an object or array class (see Type.getInternalName()).
public void visitVarInsn(int opcode, int var)
Visits a local variable instruction. A local variable instruction is an instruction that loads or stores the value of a local variable.
opcodethe 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.
varthe operand of the instruction to be visited. This operand is the index of a local variable.