CheckMethodAdapter (ASM 4.1 Documentation)

java.lang.Object
- org.objectweb.asm.MethodVisitor
- - org.objectweb.asm.util.CheckMethodAdapter

```
public class CheckMethodAdapter
extends MethodVisitor
```
A MethodVisitor that checks that its methods are properly used. More precisely this method adapter checks each instruction individually, i.e., each visit method checks some preconditions based only on its arguments - such as the fact that the given opcode is correct for a given visit method. This adapter can also perform some basic data flow checks (more precisely those that can be performed without the full class hierarchy - see BasicVerifier). For instance in a method whose signature is void m (), the invalid instruction IRETURN, or the invalid sequence IADD L2I will be detected if the data flow checks are enabled. These checks are enabled by using the CheckMethodAdapter(int,String,String,MethodVisitor,Map) constructor. They are not performed if any other constructor is used.

Author:

Eric Bruneton

Field Summary

Fields
Modifier and Type Field and Description

int version
The class version number.
- Fields inherited from class org.objectweb.asm.MethodVisitor
  api, mv

Fields
Modifier and Type	Field and Description
`int`	`version` The class version number.

Constructor Summary

Constructors
Modifier	Constructor and Description
`protected`	`CheckMethodAdapter(int api, MethodVisitor mv, Map<Label,Integer> labels)` Constructs a new `CheckMethodAdapter` object.
	`CheckMethodAdapter(int access, String name, String desc, MethodVisitor cmv, Map<Label,Integer> labels)` Constructs a new `CheckMethodAdapter` object.
	`CheckMethodAdapter(MethodVisitor mv)` Constructs a new `CheckMethodAdapter` object.
	`CheckMethodAdapter(MethodVisitor mv, Map<Label,Integer> labels)` Constructs a new `CheckMethodAdapter` object.

Method Summary

Methods
Modifier and Type	Method and Description
`AnnotationVisitor`	`visitAnnotation(String desc, boolean visible)` Visits an annotation of this method.
`AnnotationVisitor`	`visitAnnotationDefault()` Visits the default value of this annotation interface method.
`void`	`visitAttribute(Attribute attr)` Visits a non standard attribute of this method.
`void`	`visitCode()` Starts the visit of the method's code, if any (i.e. non abstract method).
`void`	`visitEnd()` Visits the end of the method.
`void`	`visitFieldInsn(int opcode, String owner, String name, String desc)` Visits a field instruction.
`void`	`visitFrame(int type, int nLocal, Object[] local, int nStack, Object[] stack)` Visits the current state of the local variables and operand stack elements.
`void`	`visitIincInsn(int var, int increment)` Visits an IINC instruction.
`void`	`visitInsn(int opcode)` Visits a zero operand instruction.
`void`	`visitIntInsn(int opcode, int operand)` Visits an instruction with a single int operand.
`void`	`visitInvokeDynamicInsn(String name, String desc, Handle bsm, Object... bsmArgs)` Visits an invokedynamic instruction.
`void`	`visitJumpInsn(int opcode, Label label)` Visits a jump instruction.
`void`	`visitLabel(Label label)` Visits a label.
`void`	`visitLdcInsn(Object cst)` Visits a LDC instruction.
`void`	`visitLineNumber(int line, Label start)` Visits a line number declaration.
`void`	`visitLocalVariable(String name, String desc, String signature, Label start, Label end, int index)` Visits a local variable declaration.
`void`	`visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels)` Visits a LOOKUPSWITCH instruction.
`void`	`visitMaxs(int maxStack, int maxLocals)` Visits the maximum stack size and the maximum number of local variables of the method.
`void`	`visitMethodInsn(int opcode, String owner, String name, String desc)` Visits a method instruction.
`void`	`visitMultiANewArrayInsn(String desc, int dims)` Visits a MULTIANEWARRAY instruction.
`AnnotationVisitor`	`visitParameterAnnotation(int parameter, String desc, boolean visible)` Visits an annotation of a parameter this method.
`void`	`visitTableSwitchInsn(int min, int max, Label dflt, Label... labels)` Visits a TABLESWITCH instruction.
`void`	`visitTryCatchBlock(Label start, Label end, Label handler, String type)` Visits a try catch block.
`void`	`visitTypeInsn(int opcode, String type)` Visits a type instruction.
`void`	`visitVarInsn(int opcode, int var)` Visits a local variable instruction.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - version
```
public int version
```
    The class version number.
- Constructor Detail
  - CheckMethodAdapter
```
public CheckMethodAdapter(MethodVisitor mv)
```
    Constructs a new CheckMethodAdapter object. This method adapter will not perform any data flow check (see CheckMethodAdapter(int,String,String,MethodVisitor,Map)). Subclasses must not use this constructor. Instead, they must use the CheckMethodAdapter(int, MethodVisitor, Map) version.
    
    Parameters:
    mv - the method visitor to which this adapter must delegate calls.
  - CheckMethodAdapter
```
public CheckMethodAdapter(MethodVisitor mv,
                  Map<Label,Integer> labels)
```
    Constructs a new CheckMethodAdapter object. This method adapter will not perform any data flow check (see CheckMethodAdapter(int,String,String,MethodVisitor,Map)). Subclasses must not use this constructor. Instead, they must use the CheckMethodAdapter(int, MethodVisitor, Map) version.
    
    Parameters:
    mv - the method visitor to which this adapter must delegate calls.
    labels - a map of already visited labels (in other methods).
  - CheckMethodAdapter
```
protected CheckMethodAdapter(int api,
                  MethodVisitor mv,
                  Map<Label,Integer> labels)
```
    Constructs a new CheckMethodAdapter object. This method adapter will not perform any data flow check (see CheckMethodAdapter(int,String,String,MethodVisitor,Map)).
    
    Parameters:
    mv - the method visitor to which this adapter must delegate calls.
    labels - a map of already visited labels (in other methods).
  - CheckMethodAdapter
```
public CheckMethodAdapter(int access,
                  String name,
                  String desc,
                  MethodVisitor cmv,
                  Map<Label,Integer> labels)
```
    Constructs a new CheckMethodAdapter object. This method adapter will perform basic data flow checks. For instance in a method whose signature is void m (), the invalid instruction IRETURN, or the invalid sequence IADD L2I will be detected.
    
    Parameters:
    access - the method's access flags.
    name - the method's name.
    desc - the method's descriptor (see Type).
    cmv - the method visitor to which this adapter must delegate calls.
    labels - a map of already visited labels (in other methods).
- Method Detail
  - visitAnnotation
```
public AnnotationVisitor visitAnnotation(String desc,
                                boolean visible)
```
    Description copied from class: MethodVisitor
    
    Visits an annotation of this method.
    
    Overrides:
    
    visitAnnotation in class MethodVisitor
    
    Parameters:
    desc - the class descriptor of the annotation class.
    visible - true if the annotation is visible at runtime.
    
    Returns:
    a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.
  - visitAnnotationDefault
```
public AnnotationVisitor visitAnnotationDefault()
```
    Description copied from class: MethodVisitor
    
    Visits the default value of this annotation interface method.
    
    Overrides:
    
    visitAnnotationDefault in class MethodVisitor
    
    Returns:
    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.
  - visitParameterAnnotation
```
public AnnotationVisitor visitParameterAnnotation(int parameter,
                                         String desc,
                                         boolean visible)
```
    Description copied from class: MethodVisitor
    
    Visits an annotation of a parameter this method.
    
    Overrides:
    
    visitParameterAnnotation in class MethodVisitor
    
    Parameters:
    parameter - the parameter index.
    desc - the class descriptor of the annotation class.
    visible - true if the annotation is visible at runtime.
    
    Returns:
    a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.
  - visitAttribute
```
public void visitAttribute(Attribute attr)
```
    Description copied from class: MethodVisitor
    
    Visits a non standard attribute of this method.
    
    Overrides:
    
    visitAttribute in class MethodVisitor
    
    Parameters:
    attr - an attribute.
  - visitCode
```
public void visitCode()
```
    Description copied from class: MethodVisitor
    
    Starts the visit of the method's code, if any (i.e. non abstract method).
    
    Overrides:
    
    visitCode in class MethodVisitor
  - visitFrame
```
public void visitFrame(int type,
              int nLocal,
              Object[] local,
              int nStack,
              Object[] stack)
```
    Description copied from class: MethodVisitor
    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 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 ( nStack 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 (nLocal 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 (nLocals 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).
    Overrides:
    
    visitFrame in class MethodVisitor
    
    Parameters:
    type - 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.
    nLocal - the number of local variables in the visited frame.
    local - 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), and uninitialized types by Label objects (this label designates the NEW instruction that created this uninitialized value).
    nStack - the number of operand stack elements in the visited frame.
    stack - the operand stack types in this frame. This array must not be modified. Its content has the same format as the "local" array.
  - visitInsn
```
public void visitInsn(int opcode)
```
    Description copied from class: MethodVisitor
    
    Visits a zero operand instruction.
    
    Overrides:
    
    visitInsn in class MethodVisitor
    
    Parameters:
    opcode - 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.
  - visitIntInsn
```
public void visitIntInsn(int opcode,
                int operand)
```
    Description copied from class: MethodVisitor
    
    Visits an instruction with a single int operand.
    
    Overrides:
    
    visitIntInsn in class MethodVisitor
    
    Parameters:
    opcode - the opcode of the instruction to be visited. This opcode is either BIPUSH, SIPUSH or NEWARRAY.
    operand - 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.
  - visitVarInsn
```
public void visitVarInsn(int opcode,
                int var)
```
    Description copied from class: MethodVisitor
    
    Visits a local variable instruction. A local variable instruction is an instruction that loads or stores the value of a local variable.
    
    Overrides:
    
    visitVarInsn in class MethodVisitor
    
    Parameters:
    opcode - 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.
    var - the operand of the instruction to be visited. This operand is the index of a local variable.
  - visitTypeInsn
```
public void visitTypeInsn(int opcode,
                 String type)
```
    Description copied from class: MethodVisitor
    
    Visits a type instruction. A type instruction is an instruction that takes the internal name of a class as parameter.
    
    Overrides:
    
    visitTypeInsn in class MethodVisitor
    
    Parameters:
    opcode - the opcode of the type instruction to be visited. This opcode is either NEW, ANEWARRAY, CHECKCAST or INSTANCEOF.
    type - the operand of the instruction to be visited. This operand must be the internal name of an object or array class (see getInternalName).
  - visitFieldInsn
```
public void visitFieldInsn(int opcode,
                  String owner,
                  String name,
                  String desc)
```
    Description copied from class: MethodVisitor
    
    Visits a field instruction. A field instruction is an instruction that loads or stores the value of a field of an object.
    
    Overrides:
    
    visitFieldInsn in class MethodVisitor
    
    Parameters:
    opcode - the opcode of the type instruction to be visited. This opcode is either GETSTATIC, PUTSTATIC, GETFIELD or PUTFIELD.
    owner - the internal name of the field's owner class (see getInternalName).
    name - the field's name.
    desc - the field's descriptor (see Type).
  - visitMethodInsn
```
public void visitMethodInsn(int opcode,
                   String owner,
                   String name,
                   String desc)
```
    Description copied from class: MethodVisitor
    
    Visits a method instruction. A method instruction is an instruction that invokes a method.
    
    Overrides:
    
    visitMethodInsn in class MethodVisitor
    
    Parameters:
    opcode - the opcode of the type instruction to be visited. This opcode is either INVOKEVIRTUAL, INVOKESPECIAL, INVOKESTATIC or INVOKEINTERFACE.
    owner - the internal name of the method's owner class (see getInternalName).
    name - the method's name.
    desc - the method's descriptor (see Type).
  - visitInvokeDynamicInsn
```
public void visitInvokeDynamicInsn(String name,
                          String desc,
                          Handle bsm,
                          Object... bsmArgs)
```
    Description copied from class: MethodVisitor
    
    Visits an invokedynamic instruction.
    
    Overrides:
    
    visitInvokeDynamicInsn in class MethodVisitor
    
    Parameters:
    name - the method's name.
    desc - the method's descriptor (see Type).
    bsm - the bootstrap method.
    bsmArgs - the bootstrap method constant arguments. Each argument must be an Integer, Float, Long, Double, String, Type or Handle value. This method is allowed to modify the content of the array so a caller should expect that this array may change.
  - visitJumpInsn
```
public void visitJumpInsn(int opcode,
                 Label label)
```
    Description copied from class: MethodVisitor
    
    Visits a jump instruction. A jump instruction is an instruction that may jump to another instruction.
    
    Overrides:
    
    visitJumpInsn in class MethodVisitor
    
    Parameters:
    opcode - 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 - the operand of the instruction to be visited. This operand is a label that designates the instruction to which the jump instruction may jump.
  - visitLabel
```
public void visitLabel(Label label)
```
    Description copied from class: MethodVisitor
    
    Visits a label. A label designates the instruction that will be visited just after it.
    
    Overrides:
    
    visitLabel in class MethodVisitor
    
    Parameters:
    label - a Label object.
  - visitLdcInsn
```
public void visitLdcInsn(Object cst)
```
    Description copied from class: MethodVisitor
    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 {
     // throw an exception
 }
 
```
    Overrides:
    
    visitLdcInsn in class MethodVisitor
    
    Parameters:
    cst - 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 49.0, a Type of METHOD sort or a Handle for MethodType and MethodHandle constants, for classes whose version is 51.0.
  - visitIincInsn
```
public void visitIincInsn(int var,
                 int increment)
```
    Description copied from class: MethodVisitor
    
    Visits an IINC instruction.
    
    Overrides:
    
    visitIincInsn in class MethodVisitor
    
    Parameters:
    var - index of the local variable to be incremented.
    increment - amount to increment the local variable by.
  - visitTableSwitchInsn
```
public void visitTableSwitchInsn(int min,
                        int max,
                        Label dflt,
                        Label... labels)
```
    Description copied from class: MethodVisitor
    
    Visits a TABLESWITCH instruction.
    
    Overrides:
    
    visitTableSwitchInsn in class MethodVisitor
    
    Parameters:
    min - the minimum key value.
    max - the maximum key value.
    dflt - beginning of the default handler block.
    labels - beginnings of the handler blocks. labels[i] is the beginning of the handler block for the min + i key.
  - visitLookupSwitchInsn
```
public void visitLookupSwitchInsn(Label dflt,
                         int[] keys,
                         Label[] labels)
```
    Description copied from class: MethodVisitor
    
    Visits a LOOKUPSWITCH instruction.
    
    Overrides:
    
    visitLookupSwitchInsn in class MethodVisitor
    
    Parameters:
    dflt - beginning of the default handler block.
    keys - the values of the keys.
    labels - beginnings of the handler blocks. labels[i] is the beginning of the handler block for the keys[i] key.
  - visitMultiANewArrayInsn
```
public void visitMultiANewArrayInsn(String desc,
                           int dims)
```
    Description copied from class: MethodVisitor
    
    Visits a MULTIANEWARRAY instruction.
    
    Overrides:
    
    visitMultiANewArrayInsn in class MethodVisitor
    
    Parameters:
    desc - an array type descriptor (see Type).
    dims - number of dimensions of the array to allocate.
  - visitTryCatchBlock
```
public void visitTryCatchBlock(Label start,
                      Label end,
                      Label handler,
                      String type)
```
    Description copied from class: MethodVisitor
    
    Visits a try catch block.
    
    Overrides:
    
    visitTryCatchBlock in class MethodVisitor
    
    Parameters:
    start - beginning of the exception handler's scope (inclusive).
    end - end of the exception handler's scope (exclusive).
    handler - beginning of the exception handler's code.
    type - internal name of the type of exceptions handled by the handler, or null to catch any exceptions (for "finally" blocks).
  - visitLocalVariable
```
public void visitLocalVariable(String name,
                      String desc,
                      String signature,
                      Label start,
                      Label end,
                      int index)
```
    Description copied from class: MethodVisitor
    
    Visits a local variable declaration.
    
    Overrides:
    
    visitLocalVariable in class MethodVisitor
    
    Parameters:
    name - the name of a local variable.
    desc - the type descriptor of this local variable.
    signature - the type signature of this local variable. May be null if the local variable type does not use generic types.
    start - the first instruction corresponding to the scope of this local variable (inclusive).
    end - the last instruction corresponding to the scope of this local variable (exclusive).
    index - the local variable's index.
  - visitLineNumber
```
public void visitLineNumber(int line,
                   Label start)
```
    Description copied from class: MethodVisitor
    
    Visits a line number declaration.
    
    Overrides:
    
    visitLineNumber in class MethodVisitor
    
    Parameters:
    line - a line number. This number refers to the source file from which the class was compiled.
    start - the first instruction corresponding to this line number.
  - visitMaxs
```
public void visitMaxs(int maxStack,
             int maxLocals)
```
    Description copied from class: MethodVisitor
    
    Visits the maximum stack size and the maximum number of local variables of the method.
    
    Overrides:
    
    visitMaxs in class MethodVisitor
    
    Parameters:
    maxStack - maximum stack size of the method.
    maxLocals - maximum number of local variables for the method.
  - visitEnd
```
public void visitEnd()
```
    Description copied from class: MethodVisitor
    
    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.
    
    Overrides:
    
    visitEnd in class MethodVisitor

Class CheckMethodAdapter

Field Summary

Fields inherited from class org.objectweb.asm.MethodVisitor

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

version

Constructor Detail

CheckMethodAdapter

CheckMethodAdapter

CheckMethodAdapter

CheckMethodAdapter

Method Detail

visitAnnotation

visitAnnotationDefault

visitParameterAnnotation

visitAttribute

visitCode

visitFrame

visitInsn

visitIntInsn

visitVarInsn

visitTypeInsn

visitFieldInsn

visitMethodInsn

visitInvokeDynamicInsn

visitJumpInsn

visitLabel

visitLdcInsn

visitIincInsn

visitTableSwitchInsn

visitLookupSwitchInsn

visitMultiANewArrayInsn

visitTryCatchBlock

visitLocalVariable

visitLineNumber

visitMaxs

visitEnd