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Not all access bits make sense for all declarations: for example, the "super" and "interface" access flags are applied to classes only.

If an access bit is used improperly, the assembler prints a warning, but places the bit in the access set.

Note that deprecated and synthetic keywords are not translated to access flags in the Java sense. For these jasm generates a corresponding Deprecated or Synthetic attributes instead of access bits. The synthetic access flag is used to mark compiler generated members not seen in the source (for example, a field reference to an anonymous outer class).

Warning
icon false
TAG: one of       int float long double Asciz String class Field Method NameAndType InterfaceMethod MethodType MethodHandle InvokeDynamic

 

Local names represent labels, trap-labels and local variables. Their scope is constrained by method parenthesis.

 

Warning
icon false
LOCAL_NAME:       IDENT CONSTANT_INDEX:       #NUMBER

 

Each CONSTANT_INDEX represents a reference into the constant pool at the specified location.

General Class Structure

Warning
icon false
INTERFACES: list of       CONSTANT_CELL(class) TOP_LEVEL_COMPONENT: one of       CONSTANT_DECLARATION FIELD_DECLARATION METHOD_DECLARATION INNER_CLASS_DECARATIONS CLASS: sequence of     ANNOTATIONS CLASS_ACCESS CONSTANT_CELL(class) [extends CONSTANT_CELL(class)] [implements INTERFACES] [version INTEGER:INTEGER] { [TOP_LEVEL_COMPONENT...] } CLASS_ACCESS: list of     [public][final][super][interface][abstract][synthetic][annotation][enum]

 

The extends CONSTANT_CELL(class) clause places the "super" element of the class file. The implements INTERFACES clause places the table of interfaces. Since the assembler does not distinguish interfaces and ordinary classes (the only difference is one access bit), the table of interfaces of an interface class must be declared with implements keyword, and not extends, as in Java language.

Note:The last two rules allow TOP_LEVEL_COMPONENT to appear in any order and number. For example, you can split constant pool table into several parts, mixing constants and method declarations.

General Source File Structure

 

Warning
icon false
PACKAGE_DECLARATION:     package IDENT;

 

Package declaration can appear only once in source file.

 

Warning
icon false
SOURCE_FILE: sequence of     PACKAGE_DECLARATION CLASS...

 

The Constant Pool and Constant Elements

A CONSTANT_CELL refers to an element in the constant pool. It may refer to the element either by its index or its value:

 

Warning
icon false
CONSTANT_CELL:     CONSTANT_INDEX     TAGGED_CONSTANT_VALUE

 

Generic rule for TAGGED_CONSTANT_VALUE is:

 

Warning
icon false
TAGGED_CONSTANT_VALUE:     [TAG] CONSTANT_VALUE

 

A TAG may be omitted when the context only allows one kind of a tag. For example, the argument of an anewarray instruction should be a CONSTANT_CELL which represents a class, so instead of

    anewarray class java/lang/Object

one may write:

    anewarray java/lang/Object

It is possible to write another tag, e.g.:

    anewarray String java/lang/Object

However, the resulting program will be incorrect.

Another example of an implicit tag (eg. a context which implies tag) is the header of a class declaration. You may write:

    aClass {
    }

which is equivalent to:

    class aClass {
    }

Below, the tag implied by context will be included in the rules, e.g.:

    CONSTANT_VALUE(int).

The exact notation of CONSTANT_VALUE depends on the (explicit or implicit) TAG.

 

Warning
icon false
TAGGED_CONSTANT_VALUE: INTEGER   [INTEGER|LONG]   [FLOAT|INTEGER]   bits INTEGER   [FLOAT|DOUBLE|INTEGER|LONG]   [bits INTEGER | bits LONG]   EXTERNAL_NAME   CONSTANT_NAME   CONSTANT_NAME   NAME_AND_TYPE   CONSTANT_FIELD   CONSTANT_FIELD   INVOKESUBTAG : CONSTANT_FIELD [FIELDREF|METHODREF|INTERFACEMETHODREF] CONSTANT_NAME INVOKESUBTAG : CONSTANT_FIELD : NAME_AND_TYPE [INVOKEDYNAMIC_STATIC_ARGS]

 

 

Note

When the JASM parser encounters an InvokeDynamic constant, it creates an entry in the BootstrapMethods attribute (the BootstrapMethods attribute is produced if it has not already been created). The entry contains a reference to the MethodHandle item in the constant pool, and, optionally, a sequence of references to additional static arguments (ldc-type constants) to the bootstrap method.

INVOKESUBTAGs for MethodHandle and (const) InvokeDynamic are defined as follows:

 

Warning
icon false
INVOKESUBTAG: REF_GETFIELD [1] REF_GETSTATIC [2] REF_PUTFIELD [3] REF_PUTSTATIC [4] REF_INVOKEVIRTUAL [5] REF_INVOKESTATIC [6] REF_INVOKESPECIAL [7] REF_NEWINVOKESPECIAL [8] REF_INVOKEINTERFACE [9]

 

Static arguments for an InvokeDynamic constant are defined as follows:

 

Warning
icon false
INVOKEDYNAMIC_STATIC_ARGUMENTS:     INVOKEDYNAMIC_STATIC_ARG ',' ... INVOKEDYNAMIC_STATIC_ARG: (one of)     INVOKEDYNAMIC_STATIC_ARG_CONSTANT_VALUE INVOKEDYNAMIC_STATIC_ARG_CONSTANT_VALUE: int INTEGER long [INTEGER|LONG] float [FLOAT|INTEGER] double [FLOAT|DOUBLE|INTEGER|LONG] class CONSTANT_NAME String CONSTANT_NAME MethodHandle INVOKESUBTAG:CONSTANT_FIELD MethodType CONSTANT_NAME

 

INTEGER, LONG, FLOAT, and DOUBLE correspond to IntegerLiteral and FloatingPointLiteral as described in The Java Language Specification. If a double-word constant (LONG or DOUBLE) is represented with a single-word value (INTEGER or FLOAT, respectively), single-word value is simply promoted to double-word, as described in The Java Language Specification. If floating-point constant (FLOAT or DOUBLE) is represented with an integral value (INTEGER or LONG, respectively), the result depends on whether the integral number is preceded with the keyword "bits". If "bits" is not used, the result is a floating-point number closest in value to the decimal number. If the keyword "bits" is used, the floating-point constant takes bits of the integral value without conversion.

Thus,

   float 2;

means the same as

   float 2.0f;

and the same as

   float bits 0x40000000;

while

   float bits 2;

actually means the same as

   float bits 0x00000002;

and the same as

   float 2.8026e-45f

 

Warning
icon false
CONSTANT_NAME:     CONSTANT_INDEX     EXTERNAL_NAME EXTERNAL_NAME:     IDENT STRING

 

External names are names of class, method, field, or type, which stay in resulting .class file, and may be represented both by IDENT or by STRING (which is useful when name contains non-letter characters).

 

Warning
icon false
NAME_AND_TYPE:     CONSTANT_INDEX     CONSTANT_NAME:CONSTANT_NAME

 

In this second example, the first CONSTANT_NAME denotes the name of a field and second denotes its type.

 

Warning
icon false
CONSTANT_FIELD:     CONSTANT_INDEX     [CONSTANT_NAME.]NAME_AND_TYPE

 

In this third example, CONSTANT_NAME denotes to the class of a field. If CONSTANT_NAME is omitted, the current class is assumed.

Constant Declarations

Constant declarations are demonstrated in the examples below:

Info
icon false
const #1=int 1234 , #2=String "a string" , #3=Method get:I ;

 

Warning
icon false
CONSTANT_DECLARATION:     const CONSTANT_DECLARATORS ; CONSTANT_DECLARATORS: list of     CONSTANT_DECLARATOR CONSTANT_DECLARATOR:     CONSTANT_INDEX = TAGGED_CONSTANT_VALUE

 

Field Variables

 

Warning
icon false
FIELD_DECLARATION:     ANNOTATIONS FIELD_ACCESS Field FIELD_DECLARATORS ; FIELD_DECLARATORS: list of     FIELD_DECLARATOR FIELD_DECLARATOR:     EXTERNAL_NAME:CONSTANT_NAME [ = TAGGED_CONSTANT_VALUE ] FIELD_ACCESS: list of     [public|private|protected][final][static][volatile][transient][synthetic][enum]

 

Example:

Info
icon false
public static Field field1:I = int 1234, field2:S ;

Access bits (public and static) are applied both to field1 and field2. The EXTERNAL_NAME denotes the name of the field, CONSTANT_NAME denotes its type, TAGGED_CONSTANT_VALUEdenotes initial value.

Method Declarations

 

Warning
icon false
METHOD_DECLARATION: sequence of     ANNOTATIONS METHOD_ACCESS Method     EXTERNAL_NAME:CONSTANT_NAME     [THROWS]     STACK_SIZE     [LOCAL_VAR_SIZE]     { INSTRUCTION_STATEMENT... }

 

The EXTERNAL_NAME denotes the name of the method, CONSTANT_NAME denotes its type.

 

Warning
icon false
METHOD_ACCESS: list of     [public|private|protected][static][final][synthetic][bridge][varargs] [native][abstract][strict][synthetic] THROWS:     throws EXCEPTIONS EXCEPTIONS: list of     CONSTANT_CELL(class)

 

The meaning of the THROWS clause is the same as in Java Language Specification - it forms Exceptions attribute of a method. Jasm itself does not use this attribute in any way.

 

Warning
icon false
STACK_SIZE:     stack NUMBER

 

The NUMBER denotes maximum operand stack size of the method.

 

Warning
icon false
LOCAL_VAR_SIZE:     locals NUMBER

 

The NUMBER denotes number of local variables of the method. If omitted, it is calculated by assembler according to the signature of the method and local variable declarations.

Instructions

 

VM Instructions

Warning
icon false
INSTRUCTION_STATEMENT:     [NUMBER] [LABEL:] INSTRUCTION|PSEUDO_INSTRUCTION ;

 

Jasm allows for a NUMBER (which is ignored) at the beginning of each line. This is allowed in order to remain consistent with the jdis disassembler. Jdis puts line numbers in disassembled code that may be reassembled using Jasm without any additional modifications.

Warning
icon false
INSTRUCTION:     OPCODE [ARGUMENTS] ARGUMENTS: list of     ARGUMENT ARGUMENT:     NUMBER LABEL LOCAL_VARIABLE TRAP_IDENT CONSTANT_CELL SWITCHTABLE TYPE LABEL:     NUMBER IDENT LOCAL_VARIABLE:     NUMBER IDENT TRAP_IDENT:     IDENT TYPE:     NUMBER boolean byte char int float long double class SWITCHTABLE:     { [NUMBER:LABEL...] [default:LABEL] }

 

SWITCHTABLE example: Java_text

Note
icon false
switch (x) { case 11: x=1; break; case 12: x=2; break; default: x=3; }

will be coded in assembler as follows:

Info
icon false
tableswitch { 11: L24; 12: L29; default: L34 } L24: iconst_1; istore_1; goto L36; L29: iconst_2 ; istore_1; goto L36; L34: iconst_3; istore_1; L36: ....

OPCODE is any mnemocode from the instruction set. If mnemocode needs an ARGUMENT, it cannot be omitted. Moreover, the kind (and number) of the argument(s) must match the kind (and number) required by the mnemocode:

Warning
icon false
aload, astore, fload, fstore, iload, istore, lload, lstore, dload, dstore, ver, endvar: LOCAL_VARIABLE iinc: LOCAL_VARIABLE, NUMBER sipush, bipush, bytecode: NUMBER tableswitch, lookupswitch: SWITCHTABLE newarray: TYPE jsr, goto, ifeq, ifge, ifgt, ifle, iflt, ifne, if_icmpeq, if_icmpne, if_icmpge, if_icmpgt, if_icmple, if_icmplt, if_acmpeq, if_acmpne, ifnull, ifnonnull, try, endtry: LABEL jsr_w, goto_w: LABEL ldc_w, ldc2_w, ldc: CONSTANT_CELL new, anewarray, instanceof, checkcast, CONSTANT_CELL(class) multianewarray NUMBER, CONSTANT_CELL(class) putstatic, getstatic, putfield, getfield: CONSTANT_CELL(Field) invokevirtual, invokenonvirtual, invokestatic: CONSTANT_CELL(Method) invokeinterface: NUMBER, CONSTANT_CELL(Method) invokedynamic: CONSTANT_CELL(InvokeDynamic)  aaload,  aastore,  aconst_null,  aload_0,  aload_1,  aload_2,  aload_3,  aload_w ,  areturn,  arraylength,  astore_0,  astore_1,  astore_2,  astore_3,  astore_w,  athrow,  baload,  bastore,  caload,  castore,  d2f,  d2i,  d2l,  dadd,  daload,  dastore,  dcmpg,  dcmpl,  dconst_0,  dconst_1,  ddiv,  dead,  dload_0,  dload_1,  dload_2,  dload_3,  dload_w ,  dmul,  dneg,  drem,  dreturn,  dstore_0,  dstore_1,  dstore_2,  dstore_3,  dstore_w,  dsub,  dup,  dup2,  dup2_x1,  dup2_x2,  dup_x1,  dup_x2,  f2d,  f2i,  f2l,  fadd,  faload,  fastore,  fcmpg,  fcmpl,  fconst_0,  fconst_1,  fconst_2,  fdiv,  fload_0,  fload_1,  fload_2,  fload_3,  fload_w,  fmul,  fneg,  frem,  freturn ,  fstore_0,  fstore_1,  fstore_2,  fstore_3,  fstore_w,  fsub ,  i2b,  i2c,  i2d,  i2f,  i2l,  i2s,  iadd,  iaload,  iand,  iastore,  iconst_0,  iconst_1,  iconst_2,  iconst_3,  iconst_4,  iconst_5,  iconst_m1,  idiv,  iinc_w,  iload_0,  iload_1,  iload_2,  iload_3,  iload_w,  imul,  ineg,  int2byte,  int2char,  int2short,  ior,  irem,  ireturn,  ishl,  ishr,  istore_0,  istore_1,  istore_2,  istore_3,  istore_w,  isub,  iushr,  ixor,  l2d,  l2f,  l2i,  label,  ladd,  laload,  land,  lastore,  lcmp,  lconst_0,  lconst_1,  ldiv,  lload_0,  lload_1,  lload_2,  lload_3,  lload_w,  lmul,  lneg,  lor,  lrem,  lreturn,  lshl,  lshr,  lstore_0,  lstore_1,  lstore_2,  lstore_3,  lstore_w,  lsub,  lushr,  lxor,  monitorenter,  monitorexit,  nonpriv,  nop,  pop,  pop2,  priv,  ret,  return,  ret_w,  saload,  sastore,  swap,   wide <No Arguments>

 

InvokeDynamic Instructions

InvokeDynamic instructions are instructions that allow dynamic binding of methods to a call site. These instructions in JASM form are rather complex, and the JASM assembler does some of the necessary work to create a BootstrapMethods attribute for entries of binding methods.

Info
icon false
class Test version 51:0 { Method m:"()V" stack 0 locals 1 { invokedynamic REF_invokeSpecial:bsmName:"()V" // information about bootstrap method :methName:"(I)I" // dynamic call-site name ("methName") // plus the argument and return types of the call ("(I)I") int 1, long 2l; // optional sequence of additional static arguments to the // bootstrap method (ldc-type constants) } } // end Class Test

 

his JASM code has an invokedynamic instruction of the form:

 

Warning
icon false
invokedynamic (CONSTANT_CELL(INVOKEDYNAMIC))

 

where the INVOKEDYNAMIC constant is represented as specified

 

Warning
icon false
invokedynamic INVOKESUBTAG : CONSTANT_FIELD (bootstrapmethod signature) : NAME_AND_TYPE (CallSite) [Arguments (Optional)]

The JASM assembler creates the appropriate constant entries and entries into the BootstrapMethods attribute in a resulting class file.

You can also create InvokeDynamic constants and BootstrapMethods explicitly:

Info
icon false
#22; //class Test3 version 51:0 { const #1 = InvokeDynamic 0:#11; // REF_invokeSpecial:Test3.bsmName:"()V":name:"(I)I" int 1, long 2l const #2 = Asciz "Test3"; const #3 = long 2l; const #5 = class #6; // java/lang/Object const #6 = Asciz "java/lang/Object"; const #7 = Asciz "name"; const #8 = int 1; const #9 = Asciz "SourceFile"; const #10 = Asciz "Test3.jasm"; const #11 = NameAndType #7:#21; // name:"(I)I" const #12 = Asciz "()V"; const #13 = Method #22.#17; // Test3.bsmName:"()V" const #14 = Asciz "Code"; const #15 = Asciz "m"; const #16 = Asciz "BootstrapMethods"; const #17 = NameAndType #20:#12; // bsmName:"()V" const #18 = Asciz "LineNumberTable"; const #19 = MethodHandle 7:#13; // REF_invokeSpecial:Test3.bsmName:"()V" const #20 = Asciz "bsmName"; const #21 = Asciz "(I)I"; const #22 = class #2; // Test3 const #23 = class #6; // java/lang/Object Method #15:#12 stack 0 locals 1 { 0: invokedynamic #1; // InvokeDynamic REF_invokeSpecial:Test3.bsmName:"()V":name:"(I)I" int 1, long 2l; } BootstrapMethod #19 #8 #3; } // end Class Test3

 

In this example, const #1 = InvokeDynamic 0:#11; is the InvokeDynamic constant that refers to BootstrapMethod at index '0' in the BootstrapMethods Attribute (BootstrapMethod #19 #8 #3; which refers to the MethodHandle at const #19, plus 2 other static args (at const #8 and const #3).

 

Pseudo Instructions

Pseudo instructions are 'assembler directives', and not really instructions (in the VM sense) They typically come in two forms: Code-generating Pseudo-Instructions, and Attribute-Generating Pseudo-Instructions.

Code-Generating Pseudo-Instructions

The bytecode directive instructs the assembler to put a collection of raw bytes into the code attribute of a method:

Warning
icon false
bytecode NUMBERS     NUMBERS is list of NUMBERs (divided by COMMA).

 Inserts bytes in place of the instruction. May have any number of numeric arguments, each of them to be converted into a byte and inserted in method's code.

Attribute-Generating Pseudo-Instructions

The rest of pseudo_instructions do not produce any bytecodes, and are used to form tables: local variable table, exception table,
Stack Maps, and Stack Map Frames. Line Number Tables can not be specified, but they are constructed by the assembler itself.

 

Local Variable Table Attribute Generation

 

Warning
icon false
var LOCAL_VARIABLE     Starts local variable range endvar LOCAL_VARIABLE     Ends local variable range. LOCAL_VARIABLE means name or index of local variable table entry.

 

Example:

Note
icon false
static void main (String[] args) { Tester inst = new Tester(); inst.callSub(); }

 

will be coded in assembler as follows:

Info
icon false
static Method #8:#9 // main:"([Ljava/lang/String;)V" stack 2 locals 2 { 4 var 0; // args:"[Ljava/lang/String;". 0: new #1; // class Tester; 3: dup; 4: invokespecial #2; // Method "<init>":"()V"; 7: astore_1; 6 var 1; // inst:"LTester 8: aload_1; 9: invokevirtual #3; // Method callSub:"()V"; 7 12: return;  endvar 0, 1; }

 

 

Exception Table Attribute Generation

To generate exception table, three pseudo-instructions are used.

Warning
icon false
try TRAP_IDENT         Starts trap range     endtry TRAP_IDENT         Ends trap range     catch TRAP_IDENT CONSTANT_CELL(class)         Starts exception handler.

TRAP_IDENT represents the name or number of an exception table entry. CONSTANT_CELL in "catch" pseudo_instruction means catch type. Each exception table entry contains 4 values:start-pc, end-pc, catch-pc, catch-type. In jasm, each entry is denoted with some (local) identifier, as an example: TRAP_IDENT.

To set start-pc, place "try TRAP_IDENT" before the instruction with the desirable program counter. Similarly, use "endtry TRAP_IDENT" for end-pc and "catch TRAP_IDENT, catch-type" for catch-pc and catch-type (which is usually a constant pool reference). Try, endtry, and catch pseudoinstructions may be placed in any order. The order of entries in exception table is significant (see JVM specification). However, the only way to control this order is to place catch-clauses in appropriate textual order: assembler adds an entry in the exception table each time it encounters a catch-clause.

Example:

Note
icon false
try { try { throw new Exception("EXC"); } catch (NullPointerException e){ throw e; } catch (Exception e){ throw e; } } catch (Throwable e){ throw e; }

 

will be coded in assembler as follows:

Info
icon false
try R1, R2; // single "try" or "endtry" can start several regions new class java/lang/Exception; dup; ldc String "EXC"; invokespecial java/lang/Exception.<init>:"(Ljava/lang/String;)V"; athrow;  endtry R1;  catch R1 java/lang/NullPointerException; // only one "catch" per entry allowed   astore_1; aload_1; athrow;  catch R1 java/lang/Exception; // same region (R1) can appear in different catches astore_1; aload_1; athrow;  endtry R2;  catch R2 java/lang/Throwable; astore_1; aload_1; athrow;

 

StackMap Table Attribute Generation

Stack Maps are denoted by the pseudo-op opcode stack_map, and they can be identified by three basic items:

Warning
icon false
stackMap_Item_MapType = (bogus | int | float | double | long | null | this | CP) stackMap_Item_Object = CONSTANT_CELL_CLASS stackMap_Item_NewObject = at LABEL

All stack_map directives are collected by the assembler, and are used to create a StackMap Table attribute.

Example 1 (MapType):

Info
icon false
public Method "<init>":"()V"     stack 1 locals 1 {        aload_0;        invokespecial    Method java/lang/Object."<init>":"()V";         return;         stack_frame_type full;           stack_map bogus;         ... }

Example 2 (Object):

Info
icon false
public Method "<init>":"()V"     stack 2 locals 1 {         ...         stack_map class java/lang/Object;         nop;         return; }

Example 3 (NewObject):

Info
icon false
public Method "<init>":"()V"     stack 2 locals 1 {         ...         stack_map at L5;         nop;         return; }

StackFrameType Table Attribute Generation

StackFrameTypes are similar assembler directives as StackMap. These directives can appear anywhere in the code, and the assembler will collect them to produce a StackFrameType attribute.

Warning
icon false
frame_type = ( same | stack1 | stack1_ex | chop1 | chop2 | chop3 | same_ex | append | full )

Example 1 (full stack frame type):

 

Info
icon false
public Method "<init>":"()V"     stack 1 locals 1 {        aload_0;        invokespecial    Method java/lang/Object."<init>":"()V";         return;         stack_frame_type full;         stack_map bogus;         ... }

 

Example 2 (append, chop2, and same stack frame types):

 

Info
icon false
public Method foo:"(Z)V" stack 2 locals 5 {         ... iload_2; iconst_2; if_icmpge L30; L27: stack_frame_type append; locals_map int, int; iconst_2; istore 4; L30: stack_frame_type chop2; goto L9; L33: stack_frame_type same; getstatic Field java/lang/System.out:"Ljava/io/PrintStream;"; ldc String "Chop2 attribute test"; invokevirtual Method java/io/PrintStream.println:"(Ljava/lang/String;)V"; return;         ... }

 

LocalsMap Table

Locals Maps are typically associated with a stack_frame_type, and are accumulated per stack frame. They typically follow a stack_frame_type directive.

Warning
icon false
locals_type = stackMap_Item_MapType | CONSTANT_CELL_CLASS

Example (a locals map specifying 2 ints):

 

Info
icon false
public Method foo:"(Z)V" stack 2 locals 5 {         ... iload_2; iconst_2; if_icmpge L30; L27: stack_frame_type append; locals_map int, int; iconst_2; istore 4; L30: stack_frame_type chop2; goto L9; L33: stack_frame_type same; getstatic Field java/lang/System.out:"Ljava/io/PrintStream;"; ldc String "Chop2 attribute test"; invokevirtual Method java/io/PrintStream.println:"(Ljava/lang/String;)V"; return;         ... }

Inner-Class Declarations

Warning
icon false
INNER_CLASS_DECLARATIONS: list of     INNER_CLASS_DECLARATION INNER_CLASS_DECLARATION:     INNER_CLASS_ACCESS InnerClass [INNER_CLASS_NAME=]? INNER_CLASS_INFO [of OUTER_CLASS_INFO]? ; INNER_CLASS_NAME:     IDENT | CPX_name INNER_CLASS_INFO:     CONSTANT_CELL(class)   OUTER_CLASS_INFO:     CONSTANT_CELL(class) INNER_CLASS_ACCESS: list of     [public|protected|private][static][final][interface][abstract] [synthetic][annotation][enum]

Example:

Info
icon false
InnerClass InCl=class test$InCl of class test;

Annotation Declarations

Member Annotations

Member annotations are a subset of the basic annotations support provided in JDK 5.0 (1.5). These are annotations that ornament Packages, Classes, and Members either visibly (accessible at runtime) or invisibly (not accessible at runtime). In JASM, visible annotations are denoted by the token @, while invisible annotations are denoted by the token @-.

Synopsis

invisibly (not accessible at runtime). In JASM, visible annotations are denoted by the token @, while invisible annotations are denoted by the token @-.

Synopsis

Warning
icon false
ANNOTATIONS:     [ANNOTATION_DECLARATION]+; ANNOTATION_DECLARATION:     @+|@- ANNOTATION_NAME [ANNOTATION_VALUE_DECLARATIONS]   The '@+' token identifies a Runtime Visible Annotation, where the '@-' token identifies a Runtime Invisible Annotation.   ANNOTATION_NAME:     IDENT ANNOTATION_VALUE_DECLARATIONS: list of (comma separated)     ANNOTATION_VALUE_DECLARATION ANNOTATION_VALUE_DECLARATION:     [ANNOTATION_VALUE_IDENT=] [ANNOTATION_VALUE] ANNOTATION_VALUE_IDENT:     IDENT ANNOTATION_VALUE:     ANNOTATION_VALUE_PRIMITIVE | Array of ANNOTATION_VALUE_PRIMITIVE ANNOTATION_VALUE_PRIMITIVE:     PRIMITIVE_TYPE | STRING | CLASS | ENUM | ANNOTATION_DECLARATION CLASS:     class CONSTANT_CELL(class) ENUM:     enum CONSTANT_CELL(class) CONSTANT_CELL(string) (where string is Enum type name) PRIMITIVE_TYPE:     BOOLEAN | BYTE | CHAR | SHORT | INTEGER | LONG | FLOAT | DOUBLE

The '@+' token identifies a Runtime Visible Annotation, where the '@-' token identifies a Runtime Invisible Annotation.

Note
    Types (Boolean, Byte, Char, and Short) are normalized into Integer's within the constant pool.
    Annotation values with these types may be identified with a keyword in front of an integer value.

     eg.       boolean true (or: boolean 1)
                 byte 20
                 char 97
                 short 2130

    Other primitive types are parsed according to normal prefix and suffix conventions
    (eg. Double = xxx.xd, Float = xxx.xf, Long = xxxL). 
    Strings are identified and delimited by '"' (quotation marks).

   Keywords 'class' and 'enum' identify those annotation types explicitly. Values within classes and enums may
   either be identifiers (strings) or Constant Pool IDs.

   Annotations specified as the value of an Annotation field are identified by the JASM annotation keywords '@+' and '@-'.

   Arrays are delimited by '{' and '}' marks, with individual elements delimited by ',' (comma).

Examples

Example 1 (Class Annotation, Visible)

 

Info
icon false
@+ClassPreamble { author = "John Doe", date = "3/17/2002", currentRevision = 6, lastModified = "4/12/2004", lastModifiedBy = "Jane Doe", reviewers = { "Alice", "Bob", "Cindy"} } super public class MyClass version 50:0 {  ...

 

Example 2 (Field Annotation, Invisible)

Info
icon false
@-FieldPreamble {  author = "Mustafa", date = "3/17/2009", currentRevision = 4 } Field foo:I; ...

Example 3 (Field Annotation, All subtypes)

Info
icon false
@+FieldPreamble { boolAnnot = boolean 1, // Boolean charBear = char 97, // Char sharkByte = byte 17, // Byte shortCircuit = short 4386, // Short integerHead = 42, // Int longJohnSilver = 55l, // Long floatBoat = 1.0f, // Float doubleDip = 10.0d, // Double stringBeans = "foo", // String severity = enum FieldPreamble$Severity IMPORTANT, // Enum classAnnot = class FieldPreamble$FooBall, // Class tm = @+Trademark { description = "embedded", owner = "ktl"} // Annotation } Field foo:I; ...

Note:
 JASM does not enforce the annotation value declarations like a compiler would.  It only checks to see that an annotation structure is well-formed.

Type Annotations

Member annotations are a subset of the basic annotations support provided in JDK 7.0 (1.7). These are annotations that ornament Packages, Classes, and Members either visibly (accessible at runtime) or invisibly (not accessible at runtime). In JASM, visible annotations are denoted by the token @T+, while invisible annotations are denoted by the token @T-.

Synopsis

Warning
icon false
TYPE_ANNOTATION_DECLARATION:@T+|@T- ANNOTATION_NAME [TYPE_ANNOTATION_VALUE_DECLARATIONS] TYPE_ANNOTATION_VALUE_DECLARATIONS: list of (comma separated) TYPE_ANNOTATION_VALUE_DECLARATION TYPE_ANNOTATION_VALUE_DECLARATION:{ { ANNOTATION_VALUE_DECLARATION+ } TARGET PATH } TARGET:{ TARGET_TYPE TARGET_INFO } TARGET_TYPE:           TARGET_TYPE: TARGET_INFO_TYPE: CLASS_TYPE_PARAMETER  TYPEPARAM METHOD_TYPE_PARAMETER   TYPEPARAM CLASS_EXTENDS  SUPERTYPE CLASS_TYPE_PARAMETER_BOUND  TYPEPARAM_BOUND METHOD_TYPE_PARAMETER_BOUND TYPEPARAM_BOUND FIELD  EMPTY METHOD_RETURN  EMPTY| METHOD_RECEIVER EMPTY METHOD_FORMAL_PARAMETER METHODPARAM THROWS EXCEPTION LOCAL_VARIABLE LOCALVAR RESOURCE_VARIABLE LOCALVAR EXCEPTION_PARAM CATCH INSTANCEOF OFFSET NEW OFFSET CONSTRUCTOR_REFERE CE_RECEIVER OFFSET METHOD_REFERENCE_RECEIVER OFFSET  CAST TYPEARG CONSTRUCTOR_INVOCATION_TYPE_ARGUMENT TYPEARG METHOD_INVOCATION_TYPE_ARGUMENT TYPEARG CONSTRUCTOR_REFERENCE_TYPE_ARGUMENT TYPEARG METHOD_REFERENCE_TYPE_ARGUMENT TYPEARG   TARGET_INFO_TYPE: TYPEPARAM | SUPERTYPE | TYPEPARAM_BOUND | EMPTY | METHODPARAM | EXCEPTION | LOCALVAR | CATCH | OFFSET |  TYPEARG TYPEPARAM: paramIndex(INTEGER) SUPERTYPE: typeIndex(INTEGER)typeIndex(INTEGER) TYPEPARAM_BOUND: paramIndex(INTEGER) boundIndex(INTEGER) EMPTY:  METHODPARAM: index(paramIndex(INTEGER) EXCEPTION: typeIndex(INTEGER)  LOCALVAR: { LVENTRY }+numEntries LVENTRY: startpc(INTEGER) length(INTEGER) index(INTEGER)  offset(INTEGER) TYPEARG: offset(INTEGER) typeIndex(INTEGER) PATH: list of (space separated) { PATH_ENTRY+ } { PATH_KIND PATH_INDEX }

 

PATH_KIND: ARRAY | INNER_TYPE | WILDCARD | TYPE_ARGUMENT PATH_INDEX: INTEGER

 




Parameter Names and Parameter Annotations

Parameter annotations are another subset of the basic annotations support provided in JDK 5.0 (1.5). These are annotations that ornament Parameters to methods either visibly (accessible at runtime) or invisibly (not accessible at runtime). In JASM, visible parameter annotations are denoted by the token @+, while invisible parameter annotations are denoted by the token @-.

Parameter names come from an attribute introduced in JDK 8.0 (1.8).  These are fixed parameter names that are used to ornament parameters on methods.  In Jasm, parameter names are identified by the token # followed by { } braclets

Synopsis

Examples

Example 1 (Parameter Annotation)
Java Code

 

Note
icon false
public class MyClass2 { ... public int doSomething( @VisParamPreamble ( author = "gummy" ) @InVisParamPreamble ( author = "bears" ) int barber, boolean of, @VisParamPreamble ( author = "sour" ) @InVisParamPreamble ( author = "worms" ) int seville, @InVisParamPreamble1 ( reviewers = {"Dilbert", "Garfield"} ) boolean pastrami) { ... } ... }

JASM Code

Note:  The first two parameters are named ('P0'- 'P3').  Since this is a compiler controlled option, there is no way to specify parameter naming in Java source.

 

Info
icon false
super public class MyClass2 version 50:0 { ... public Method doSomething:"(IZIZ)I" stack 2 locals 5 0: #{P0 mandated} @+VisParamPreamble { author = "gummy" } @-InVisParamPreamble { author = "bears" } 1: #{P1 final synthetic mandated}   2: #{P2 mandated} @+VisParamPreamble { author = "sour" } @-InVisParamPreamble { author = "worms" } 3: #{P3 mandated} @-InVisParamPreamble1 { reviewers = { "Dilbert", "Garfield"} } { ... } } // end Class MyClass2

 

Default Annotations

  Default annotations are another subset of the basic annotations support provided in JDK 5.0 (1.5). These are annotations that ornament Annotations either visibly (accessible at runtime) or invisibly (not accessible at runtime). Default annotations specify a default value for a given annotation field.

Synopsis

Examples

Example 1 (Default Annotation)
Java Code

 

Note
icon false
import java.lang.annotation.*; @Retention(RetentionPolicy.RUNTIME) @interface Meth2Preamble {    String author() default "John Steinbeck"; }

JASM Code

 

Info
icon false
interface  Meth2Preamble     implements java/lang/annotation/Annotation     version 50:0 {  public abstract Method author:"()Ljava/lang/String;" default { "John Steinbeck" } ; } // end Class Meth2Preamble

 

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PicoJava Instructions

These instructions takes 2 bytes: prefix (254 for non-privileged variant and 255 for privileged) and the opcode itself. These instructions can be coded in assembler in 2 ways: as single mnemocode identical to the description or using "priv" and "nonpriv" instructions followed with an integer representing the opcode.

 



CATCH:

catch(INTEGER)


OFFSET:


PATH_ENTRY:


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Appendix B