The Java Version Almanac

Java Bytecode

Constant

Push constant values to operand stack.

Mnemonic	Opcode	Description
`aconst_null`	1	Push `null`
`bipush`	16	Push `byte`
`dconst_0`	14	Push `double` value `0.0`
`dconst_1`	15	Push `double` value `1.0`
`fconst_0`	11	Push `float` value `0.0`
`fconst_1`	12	Push `float` value `1.0`
`fconst_2`	13	Push `float` value `2.0`
`iconst_0`	3	Push `int` constant `0`
`iconst_1`	4	Push `int` constant `1`
`iconst_2`	5	Push `int` constant `2`
`iconst_3`	6	Push `int` constant `3`
`iconst_4`	7	Push `int` constant `4`
`iconst_5`	8	Push `int` constant `5`
`iconst_m1`	2	Push `int` constant `-1`
`lconst_0`	9	Push `long` constant
`lconst_1`	10	Push `long` constant
`ldc`	18	Push item from constant pool
`ldc_w`	19	Push item from constant pool (wide index)
`ldc2_w`	20	Push `long` or `double` from constant pool (wide index)
`sipush`	17	Push `short`

Data Source

Load

Load operand stack value from local variable.

Mnemonic	Opcode	Description
`aload`	25	Load reference from local variable
`aload_0`	42	Load reference from local variable `0`
`aload_1`	43	Load reference from local variable `1`
`aload_2`	44	Load reference from local variable `2`
`aload_3`	45	Load reference from local variable `3`
`dload`	24	Load `double` from local variable
`dload_0`	38	Load `double` from local variable `0`
`dload_1`	39	Load `double` from local variable `1`
`dload_2`	40	Load `double` from local variable `2`
`dload_3`	41	Load `double` from local variable `3`
`fload`	23	Load `float` from local variable
`fload_0`	34	Load `float` from local variable `0`
`fload_1`	35	Load `float` from local variable `1`
`fload_2`	36	Load `float` from local variable `2`
`fload_3`	37	Load `float` from local variable `3`
`iload`	21	Load `int` from local variable
`iload_0`	26	Load `int` from local variable
`iload_1`	27	Load `int` from local variable
`iload_2`	28	Load `int` from local variable
`iload_3`	29	Load `int` from local variable
`lload`	22	Load `long` from local variable
`lload_0`	30	Load `long` from local variable `0`
`lload_1`	31	Load `long` from local variable `1`
`lload_2`	32	Load `long` from local variable `2`
`lload_3`	33	Load `long` from local variable `3`

Data Source

Store

Store operand stack value to local variable.

Mnemonic	Opcode	Description
`astore`	58	Store reference into local variable
`astore_0`	75	Store reference into local variable `0`
`astore_1`	76	Store reference into local variable `1`
`astore_2`	77	Store reference into local variable `2`
`astore_3`	78	Store reference into local variable `3`
`dstore`	57	Store `double` into local variable
`dstore_0`	71	Store `double` into local variable `0`
`dstore_1`	72	Store `double` into local variable `1`
`dstore_2`	73	Store `double` into local variable `2`
`dstore_3`	74	Store `double` into local variable `3`
`fstore`	56	Store `float` into local variable
`fstore_0`	67	Store `float` into local variable `0`
`fstore_1`	68	Store `float` into local variable `1`
`fstore_2`	69	Store `float` into local variable `2`
`fstore_3`	70	Store `float` into local variable `3`
`istore`	54	Store `int` into local variable
`istore_0`	59	Store `int` into local variable `0`
`istore_1`	60	Store `int` into local variable `1`
`istore_2`	61	Store `int` into local variable `2`
`istore_3`	62	Store `int` into local variable `3`
`lstore`	55	Store `long` into local variable
`lstore_0`	63	Store `long` into local variable `0`
`lstore_1`	64	Store `long` into local variable `1`
`lstore_2`	65	Store `long` into local variable `2`
`lstore_3`	66	Store `long` into local variable `3`

Data Source

Stack

Manage operand stack.

Mnemonic	Opcode	Description
`dup`	89	Duplicate the top operand stack value
`dup_x1`	90	Duplicate the top operand stack value and insert two values down
`dup_x2`	91	Duplicate the top operand stack value and insert two or three values down
`dup2`	92	Duplicate the top one or two operand stack values
`dup2_x1`	93	Duplicate the top one or two operand stack values and insert two or three values down
`dup2_x2`	94	Duplicate the top one or two operand stack values and insert two, three, or four values down
`pop`	87	Pop the top operand stack value
`pop2`	88	Pop the top one or two operand stack values
`swap`	95	Swap the top two operand stack values

Data Source

Math

Calculate on operand stack.

Mnemonic	Opcode	Description
`dadd`	99	Add `double`
`ddiv`	111	Divide `double`
`dmul`	107	Multiply `double`
`dneg`	119	Negate `double`
`drem`	115	Remainder `double`
`dsub`	103	Subtract `double`
`fadd`	98	Add `float`
`fdiv`	110	Divide `float`
`fmul`	106	Multiply `float`
`fneg`	118	Negate `float`
`frem`	114	Remainder `float`
`fsub`	102	Subtract `float`
`iadd`	96	Add `int`
`iand`	126	Boolean AND `int`
`idiv`	108	Divide `int`
`iinc`	132	Increment local variable by constant
`imul`	104	Multiply `int`
`ineg`	116	Negate `int`
`ior`	128	Boolean OR `int`
`irem`	112	Remainder `int`
`ishl`	120	Shift left `int`
`ishr`	122	Arithmetic shift right `int`
`isub`	100	Subtract `int`
`iushr`	124	Logical shift right `int`
`ixor`	130	Boolean XOR `int`
`ladd`	97	Add `long`
`land`	127	Boolean AND `long`
`ldiv`	109	Divide `long`
`lmul`	105	Multiply `long`
`lneg`	117	Negate `long`
`lor`	129	Boolean OR `long`
`lrem`	113	Remainder `long`
`lshl`	121	Shift left `long`
`lshr`	123	Arithmetic shift right `long`
`lsub`	101	Subtract `long`
`lushr`	125	Logical shift right `long`
`lxor`	131	Boolean XOR `long`

Data Source

Conversion

Convert numeric types on operand stack.

Mnemonic	Opcode	Description
`d2f`	144	Convert `double` to `float`
`d2i`	142	Convert `double` to `int`
`d2l`	143	Convert `double` to `long`
`f2d`	141	Convert `float` to `double`
`f2i`	139	Convert `float` to `int`
`f2l`	140	Convert `float` to `long`
`i2b`	145	Convert `int` to `byte`
`i2c`	146	Convert `int` to `char`
`i2d`	135	Convert `int` to `double`
`i2f`	134	Convert `int` to `float`
`i2l`	133	Convert `int` to `long`
`i2s`	147	Convert `int` to `short`
`l2d`	138	Convert `long` to `double`
`l2f`	137	Convert `long` to `float`
`l2i`	136	Convert `long` to `int`

Data Source

Comparison

Compare values on operand stack.

Mnemonic	Opcode	Description
`dcmpg`	152	Compare `double`
`dcmpl`	151	Compare `double`
`fcmpg`	150	Compare `float`
`fcmpl`	149	Compare `float`
`lcmp`	148	Compare `long`

Data Source

Conditional

Conditional jumps depending on values on operand stack.

Mnemonic	Opcode	Description
`if_acmpeq`	165	Jump if reference comparison succeeds
`if_acmpne`	166	Jump if reference comparison succeeds
`if_icmpeq`	159	Jump if `int` comparison succeeds
`if_icmpge`	162	Jump if `int` comparison succeeds
`if_icmpgt`	163	Jump if `int` comparison succeeds
`if_icmple`	164	Jump if `int` comparison succeeds
`if_icmplt`	161	Jump if `int` comparison succeeds
`if_icmpne`	160	Jump if `int` comparison succeeds
`ifeq`	153	Jump if `int` comparison with zero succeeds
`ifge`	156	Jump if `int` comparison with zero succeeds
`ifgt`	157	Jump if `int` comparison with zero succeeds
`ifle`	158	Jump if `int` comparison with zero succeeds
`iflt`	155	Jump if `int` comparison with zero succeeds
`ifne`	154	Jump if `int` comparison with zero succeeds
`ifnonnull`	199	Jump if reference not `null`
`ifnull`	198	Jump if reference is `null`
`lookupswitch`	171	Access jump table by key match and jump
`tableswitch`	170	Access jump table by index and jump

Data Source

Objects

Interact with objects.

Mnemonic	Opcode	Description
`checkcast`	192	Check whether reference is of given type
`getfield`	180	Fetch field from object
`getstatic`	178	Get `static` field from class
`instanceof`	193	Determine if reference is of given type
`invokedynamic`	186	Invoke a dynamically-computed call site
`invokeinterface`	185	Invoke interface method
`invokespecial`	183	Directly invoke instance (initialization) method of the current class or its supertypes
`invokestatic`	184	Invoke `static` method
`invokevirtual`	182	Invoke instance method, dispatch based on class
`new`	187	Create new object
`putfield`	181	Set field in object
`putstatic`	179	Set static field in class

Data Source

Array

Create and access arrays.

Mnemonic	Opcode	Description
`aaload`	50	Load reference from array
`aastore`	83	Store into reference array
`anewarray`	189	Create new array of reference
`arraylength`	190	Get length of array
`baload`	51	Load `byte` or `boolean` from array
`bastore`	84	Store into `byte` or `boolean` array
`caload`	52	Load `char` from array
`castore`	85	Store into `char` array
`daload`	49	Load `double` from array
`dastore`	82	Store into `double` array
`faload`	48	Load `float` from array
`fastore`	81	Store into `float` array
`iaload`	46	Load `int` from array
`iastore`	79	Store into `int` array
`laload`	47	Load `long` from array
`lastore`	80	Store into `long` array
`multianewarray`	197	Create new multidimensional array
`newarray`	188	Create new array
`saload`	53	Load `short` from array
`sastore`	86	Store into `short` array

Data Source

Control Flow

Manage the control flow.

Mnemonic	Opcode	Description
`areturn`	176	Return reference from method
`athrow`	191	Throw `Throwable` reference
`dreturn`	175	Return `double` from method
`freturn`	174	Return `float` from method
`goto`	167	Unconditional jump
`goto_w`	200	Unconditional jump (wide index)
`ireturn`	172	Return `int` from method
`jsr`	168	Jump subroutine
`jsr_w`	201	Jump subroutine (wide index)
`lreturn`	173	Return `long` from method
`ret`	169	Return from subroutine
`return`	177	Return `void` from method

Data Source

Other

Various uncategorized opcodes

Mnemonic	Opcode	Description
`monitorenter`	194	Enter monitor for object
`monitorexit`	195	Exit monitor for object
`nop`	0	Do nothing
`wide`	196	Extend local variable index by additional bytes

Data Source

Reserved

Reserved opcodes for internal usage in VM implementations only.

Mnemonic	Opcode	Description
`breakpoint`	202	Reserved for internal usage in debuggers
`impdep1`	254	Reserved for internal usage in JVM
`impdep2`	255	Reserved for internal usage in JVM

Data Source