June 2010 - Boston Java Meetup Presentation on Java's Class File Format and Byte Code

1. Introduction to Class File
Format & Byte Code
By Douglas Q Hawkins
Wireless
Event Code: JM67

2. Topics
Class File Format
Byte Code
Dynamic Generation of Byte Code
Annotation Processing Tool

3. Class File Format

4. Class File Format
CA FE BA BE Minor Version Major Version
Constant Pool
Flags This Class Super Class
Interfaces
Fields
Methods
Attributes

5. Class File Format
CA FE BA BE Minor Version Major Version
Constant Pool
Flags This Class Super Class
Interfaces
Fields
Methods
Attributes

6. Class File Format
CA FE BA BE Minor Version Major Version
Constant Pool
Flags This Class Super Class
Interfaces
Fields
Methods
Attributes

7. Class File Format
CA FE BA BE Minor Version Major Version
Constant Pool
Flags This Class Super Class
Interfaces
Fields
Methods
Attributes

8. Class File Format
CA FE BA BE Minor Version Major Version
Constant Pool
d
ize
gs
on
ar
hr
ar
nc
su atile t/v
pu te d
Flags This Class Super Class
al sy
ce
iva te
tiv ct
l n
ab tfp
vo nsie
pr ec
fin r/
na ra
fa
ic
tra e
pr ic
pe
Interfaces
st
er
bl
ric
ot
at
int
st
st
Fields
Methods
Attributes

9. Class File Format
CA FE BA BE Minor Version Major Version
Constant Pool
Flags This Class Super Class
Interfaces
Fields
Methods
Attributes

10. Class File Format
CA FE BA BE Minor Version Major Version
Constant Pool
Flags This Class Super Class
Interfaces
Fields
Methods
Attributes

11. Class File Format
CA FE BA BE Minor Version Major Version
Constant Pool
Flags This Class Super Class
Interfaces
Fields
Methods
Attributes

12. Class File Format
CA FE BA BE Minor Version Major Version
Constant Pool
Flags This Class Super Class
Interfaces
Fields
Methods
Attributes

13. Class File Format
CA FE BA BE Minor Version Major Version
Constant Pool
Flags This Class Super Class
Interfaces
Fields
Methods
Attributes

14. Class File Format
CA FE BA BE Minor Version Major Version
Constant Pool
Flags This Class Super Class
Interfaces
Fields
Methods
Attributes

15. Constant Pool
C 2 UTF 10 HelloWorld
C 4 UTF 16
“java/lang/Object”
UTF 6 “<init>” UTF
3 “()V” UTF 4 “Code”
M 3 9 N&T 5 6 UTF 4
“main” UTF 22
“([Ljava/lang/String;)V”
F 13 15 C 14 UTF
16 “java/lang/System”

16. Constant Pool (continued)
N&T 16 17 UTF 3 “out”
UTF 21 “Ljava/io/PrintStream;”
S
19 UTF 11 “Hello World”
M21 23
C 22 UTF 19 “java/io/PrintStream”
N&T 24 25 UTF
7 “println”
UTF 21 (Ljava/lang/String;)V

17. Field Format
Flags Name Descriptor
Attributes

18. Name Flags
Field Format
int
er
fa
ce
st
ric
Attributes
ab tfp
s
na tra
tiv ct
tra e
vo nsie
Descriptor
l n
su atile t/v
pe ar
fin r/ ar
al sy gs
st nc
at hr
pr ic on
ot ize
pr ec
iva te d
pu te d
bl
ic

19. Field Format
Flags Name Descriptor
“name”
Attributes

20. Field Format
Flags Name Descriptor “Ljava/lang/String;”
Attributes

21. Field Format
Flags Name Descriptor
Attributes

22. Field Format
Flags Name Descriptor
Attributes
ConstantValue

23. Method Format
Flags Name Descriptor
Attributes

24. Name Flags
int
er
fa
ce
Method Format
st
ric
Attributes
ab tfp
s
na tra
tiv ct
tra e
vo nsie
Descriptor
l n
su atile t/v
pe ar
fin r/ ar
al sy gs
st nc
at hr
pr ic on
ot ize
pr ec
iva te d
pu te d
bl
ic

25. Method Format
Flags Name Descriptor
“main”
Attributes

26. Method Format
Flags Name Descriptor “([Ljava/lang/String;)V”
Attributes

27. Method Format
Flags Name Descriptor
Attributes

28. Method Format
Flags Name Descriptor
Attributes
Exceptions

29. Method Format
Flags Name Descriptor
Attributes
Exceptions
Code

30. Constant Pool
C 2 UTF 10 HelloWorld
C 4 UTF 16
“java/lang/Object”
UTF 6 “<init>” UTF
3 “()V” UTF 4 “Code”
M 3 9 N&T 5 6 UTF 4
“main” UTF 22
“([Ljava/lang/String;)V”
F 13 15 C 14 UTF
16 “java/lang/System”

31. Constant Pool
1 2
C 2 UTF 10 HelloWorld
3 4
C 4 UTF 16
“java/lang/Object”
5 6
UTF 6 “<init>” UTF
7
3 “()V” UTF 4 “Code”
8 9 10
M 3 9 N&T 5 6 UTF 4
11
“main” UTF 22
“([Ljava/lang/String;)V”
12 13 14
F 13 15 C 14 UTF
16 “java/lang/System”

32. Constant Pool
1 2
C 2 UTF 10 HelloWorld
3 4
C 4 UTF 16
“java/lang/Object”
5 6
UTF 6 “<init>” UTF
7
3 “()V” UTF 4 “Code”
8 9 10
M 3 9 N&T 5 6 UTF 4
11
“main” UTF 22
“([Ljava/lang/String;)V”
12 13 14
F 13 15 C 14 UTF
16 “java/lang/System”

33. Constant Pool
1 2
C 2 UTF 10 HelloWorld
3 4
C 4 UTF 16
“java/lang/Object”
5 6
UTF 6 “<init>” UTF
7
3 “()V” UTF 4 “Code”
8 9 10
M 3 9 N&T 5 6 UTF 4
11
“main” UTF 22
“([Ljava/lang/String;)V”
12 13 14
F 13 15 C 14 UTF
16 “java/lang/System”

34. Browsing Class File Format
JClassLib Viewer

35. Byte Code

36. Stack Based Virtual Machine
0 iconst_1
0 1 2 3
1 iconst_2
2 iadd
3 istore_0
4 iload_0

37. Stack Based Virtual Machine
0 iconst_1
0 1 2 3
1 iconst_2
2 iadd
3 istore_0
4 iload_0
1

38. Stack Based Virtual Machine
0 iconst_1
0 1 2 3
1 iconst_2
2 iadd
3 istore_0
4 iload_0
2
1

39. Stack Based Virtual Machine
0 iconst_1
0 1 2 3
1 iconst_2
2 iadd
3 istore_0
4 iload_0
1+2

40. Stack Based Virtual Machine
0 iconst_1
0 1 2 3
1 iconst_2
2 iadd
3 istore_0
4 iload_0
3

41. Stack Based Virtual Machine
0 iconst_1
0 1 2 3
1 iconst_2 3
2 iadd
3 istore_0
4 iload_0

42. Stack Based Virtual Machine
0 iconst_1
0 1 2 3
1 iconst_2 3
2 iadd
3 istore_0
4 iload_0
3

43. Operation Types
Load and Store
Arithmetic and Logic
Type Conversion
Branch Instructions
Object Creation and Manipulation
Operand Stack
Method Invocation

44. Data Types
ac ts refix
als
ns e P
ray oc
Co Cod
By ture
Ar k / L
St tan
na
te
Sig
boolean Z
Integer Types
byte B b
char C c
short S s
int I i
long J l
float F f
double D d
reference L a
void V

45. Parameters and Local Variables
static int volume(
int width,
int depth,
int height )
{
int area = width * depth;
int volume = area * height;
return volume;
}

46. Parameters and Local Variables
static int volume( 0 iload_0
int width,
1 iload_1
int depth,
int height ) 2 imul
{ 3 istore_3
int area = width * depth;
4 iload_3
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4
11ireturn

47. Parameters and Local Variables
static int volume( 0 iload_0
int width,
1 iload_1
int depth,
2 imul
e
int height )
are t
h
lum
igh
h
pt
a
dt
{ 3 istore_3
de
he
vo
wi
0 1 2 3 4
int area = width * depth;
4 iload_3
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4
11ireturn

48. Parameters and Local Variables
static int volume( 0 iload_0
int width,
1 iload_1
int depth,
2 imul
e
int height )
are t
h
lum
igh
h
pt
a
dt
{ 3 istore_3
de
he
vo
wi
0 1 2 3 4
int area = width * depth;
4 iload_3 1 2 3
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4
11ireturn

49. Parameters and Local Variables
static int volume( 0 iload_0
int width,
1 iload_1
int depth,
2 imul
e
int height )
are t
h
lum
igh
h
pt
a
dt
{ 3 istore_3
de
he
vo
wi
0 1 2 3 4
int area = width * depth;
4 iload_3 1 2 3
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4
11ireturn 1

50. Parameters and Local Variables
static int volume( 0 iload_0
int width,
1 iload_1
int depth,
2 imul
e
int height )
are t
h
lum
igh
h
pt
a
dt
{ 3 istore_3
de
he
vo
wi
0 1 2 3 4
int area = width * depth;
4 iload_3 1 2 3
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4 2
11ireturn 1

51. Parameters and Local Variables
static int volume( 0 iload_0
int width,
1 iload_1
int depth,
2 imul
e
int height )
are t
h
lum
igh
h
pt
a
dt
{ 3 istore_3
de
he
vo
wi
0 1 2 3 4
int area = width * depth;
4 iload_3 1 2 3
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4
11ireturn 2

52. Parameters and Local Variables
static int volume( 0 iload_0
int width,
1 iload_1
int depth,
2 imul
e
int height )
are t
h
lum
igh
h
pt
a
dt
{ 3 istore_3
de
he
vo
wi
0 1 2 3 4
int area = width * depth;
4 iload_3 1 2 3 2
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4
11ireturn

53. Parameters and Local Variables
static int volume( 0 iload_0
int width,
1 iload_1
int depth,
2 imul
e
int height )
are t
h
lum
igh
h
pt
a
dt
{ 3 istore_3
de
he
vo
wi
0 1 2 3 4
int area = width * depth;
4 iload_3 1 2 3 2
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4
11ireturn 2

54. Parameters and Local Variables
static int volume( 0 iload_0
int width,
1 iload_1
int depth,
2 imul
e
int height )
are t
h
lum
igh
h
pt
a
dt
{ 3 istore_3
de
he
vo
wi
0 1 2 3 4
int area = width * depth;
4 iload_3 1 2 3 2
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4 3
11ireturn 2

55. Parameters and Local Variables
static int volume( 0 iload_0
int width,
1 iload_1
int depth,
2 imul
e
int height )
are t
h
lum
igh
h
pt
a
dt
{ 3 istore_3
de
he
vo
wi
0 1 2 3 4
int area = width * depth;
4 iload_3 1 2 3 2
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4
11ireturn 6

56. Parameters and Local Variables
static int volume( 0 iload_0
int width,
1 iload_1
int depth,
2 imul
e
int height )
are t
h
lum
igh
h
pt
a
dt
{ 3 istore_3
de
he
vo
wi
0 1 2 3 4
int area = width * depth;
4 iload_3 1 2 3 2 6
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4
11ireturn

57. Parameters and Local Variables
static int volume( 0 iload_0
int width,
1 iload_1
int depth,
2 imul
e
int height )
are t
h
lum
igh
h
pt
a
dt
{ 3 istore_3
de
he
vo
wi
0 1 2 3 4
int area = width * depth;
4 iload_3 1 2 3 2 6
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4
11ireturn 6

58. Parameters and Local Variables
static int volume( 0 iload_0
int width,
1 iload_1
int depth,
2 imul
e
int height )
are t
h
lum
igh
h
pt
a
dt
{ 3 istore_3
de
he
vo
wi
0 1 2 3 4
int area = width * depth;
4 iload_3 1 2 3 2 6
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4
11ireturn

59. Static vs Virtual Methods
static int volume( 0 iload_0
int width, 1 iload_1
int depth,
2 imul
e
int height )
are t
he h
lum
h
igh
pt
a
dt
{ 3 istore_3
de
wi
vo
0 1 2 3 4 5
int area = width * depth; 4 iload_3
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4
11 ireturn

60. Static vs Virtual Methods
int volume( 0 iload_0
int width, 1 iload_1
int depth,
2 imul
e
int height )
are t
he h
lum
h
igh
pt
a
dt
{ 3 istore_3
de
wi
vo
0 1 2 3 4 5
int area = width * depth; 4 iload_3
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4
11 ireturn

61. Static vs Virtual Methods
int volume( 0 iload_0
int width, 1 iload_1
int depth,
2 imul
e
int height )
are t
he h
lum
h
igh
pt
a
dt
s
{ 3 istore_3
de
thi
wi
vo
0 1 2 3 4 5
int area = width * depth; 4 iload_3
int volume = area * height;
return volume; 5 iload_2
} 6 imul
7 istore 4
9 iload 4
11 ireturn

62. Static vs Virtual Methods
int volume( 0 iload_1
int width, 1 iload_2
int depth,
2 imul
e
int height )
are t
he h
lum
h
igh
pt
a
dt
s
{ 3 istore 4
de
thi
wi
vo
0 1 2 3 4 5
int area = width * depth; 5 iload 4
int volume = area * height;
return volume; 7 iload_3
} 8 imul
9 istore 5
11 iload 5
13 ireturn

63. Hello World
System.out.println( “Hello World” );

64. Hello World
System.out.println( “Hello World” );
0 getstatic System.out
3 ldc “Hello World”
5 invokevirtual PrintStream.println
8 return

65. Hello World
System.out.println( “Hello World” );
0 1 2 3
0 getstatic System.out
3 ldc “Hello World”
5 invokevirtual PrintStream.println
“Hello World”
8 return
System.out

66. Hello World
System.out.println( “Hello World” );
0 1 2 3
0 getstatic System.out
3 ldc “Hello World”
5 invokevirtual PrintStream.println
“Hello World”
8 return
System.out

67. Hello World
System.out.println( “Hello World” );
0 1 2 3
0 getstatic System.out
3 ldc “Hello World”
5 invokevirtual PrintStream.println
“Hello World”
8 return
System.out

68. Hello World
g
s
ms
thi
System.out.println( “Hello World” );
0 1 2 3
0 getstatic System.out
3 ldc “Hello World”
5 invokevirtual PrintStream.println
“Hello World”
8 return
System.out

69. Types of Method Invocations
invokestatic - invoke static methods
invokevirtual - invoke instance method from class
invokeinterface - invoke instance method from interface
invokespecial - invoke <init> / invoke super method

70. New Object
return new BigDecimal(“2.0”);

71. New Object
return new BigDecimal(“2.0”);
0 new BigDecimal
3 dup
4 ldc “2.0”
6 invokespecial BigDecimal.<init>
9 areturn

72. New Object
return new BigDecimal(“2.0”);
0 1 2 3
0 new BigDecimal
3 dup
4 ldc “2.0”
“2.0”
6 invokespecial BigDecimal.<init>
9 areturn

73. New Object
return new BigDecimal(“2.0”);
0 1 2 3
0 new BigDecimal
3 dup
4 ldc “2.0”
“2.0”
6 invokespecial BigDecimal.<init>
9 areturn
BigDecimal

74. New Object
return new BigDecimal(“2.0”);
0 1 2 3
0 new BigDecimal
3 dup
4 ldc “2.0”
“2.0”
6 invokespecial BigDecimal.<init>
9 areturn
BigDecimal

75. New Object
return new BigDecimal(“2.0”);
0 1 2 3
0 new BigDecimal
3 dup
4 ldc “2.0”
“2.0”
6 invokespecial BigDecimal.<init>
9 areturn
BigDecimal

76. New Object
return new BigDecimal(“2.0”);
0 1 2 3
0 new BigDecimal
3 dup
4 ldc “2.0”
“2.0”
6 invokespecial BigDecimal.<init>
9 areturn
BigDecimal

77. If / Else
static boolean isPositive( int val ){
if ( val > 0 ) {
return true;
} else {
return false;
}
}

78. If / Else
static boolean isPositive( int val ){ 0 iload_0
test
if ( val > 0 ) { 1 ifle +5 //6
return true;
4 iconst_1
} else {
if
return false; 5 ireturn
} 6 iconst_0
else
} 7 ireturn

79. If / Else
static boolean isPositive( int val ){ 0 iload_0
test
if ( val > 0 ) { 1 ifle +5 //6
return true;
4 iconst_1
} else {
if
return false; 5 ireturn
} 6 iconst_0
else
} 7 ireturn

80. If / Else
static boolean isPositive( int val ){ 0 iload_0
test
if ( val > 0 ) { 1 ifle +5 //6
return true;
4 iconst_1
} else {
if
return false; 5 ireturn
} 6 iconst_0
else
} 7 ireturn

81. If / Else
static boolean isPositive( int val ){ 0 iload_0
test
if ( val > 0 ) { 1 ifle +5 //6
return true;
4 iconst_1
} else {
if
return false; 5 ireturn
} 6 iconst_0
else
} 7 ireturn

82. If / Else
static boolean isPositive( int val ){ 0 iload_0
test
if ( val > 0 ) { 1 ifle +5 //6
return true;
4 iconst_1
} else {
if
return false; 5 ireturn
} 6 iconst_0
else
} 7 ireturn
static boolean isPositive( int val ){
return ( val > 0 );
}

83. If / Else
static boolean isPositive( int val ){
if ( val > 0 ) {
return true;
} else {
return false;
}
}
static boolean isPositive( int val ){
return ( val > 0 );
}

84. If / Else
static boolean isPositive( int val ){ 0 iload_0
test
if ( val > 0 ) { 1 ifle +5 //6
return true;
4 iconst_1
} else {
if
return false; 5 ireturn
} 6 iconst_0
else
} 7 ireturn
static boolean isPositive( int val ){
return ( val > 0 );
}

85. For Loop
static int sum( int min, int max ){
int sum = 0;
for ( int i=min; i<max; ++i ){
sum += i;
}
return sum;
}

86. before
0 iconst_0
For Loop
init & test loop
1 istore_2
2 iload_1
static int sum( int min, int max ){ 3 istore_3
int sum = 0; 4 goto +10 //14
for ( int i=min; i<max; ++i ){ 7 iload_2
loop body
sum += i; 8 iload_3
} 9 iadd
return sum; 10 istore_2
}
inc
11 iinc 3 by 1
14 iload_3
test 15 iload_1
16 if_icmplt -9 //7
19 iload_2
after
loop
20 ireturn

87. before
0 iconst_0
For Loop
init & test loop
1 istore_2
2 iload_1
static int sum( int min, int max ){ 3 istore_3
int sum = 0; 4 goto +10 //14
for ( int i=min; i<max; ++i ){ 7 iload_2
loop body
sum += i; 8 iload_3
} 9 iadd
return sum; 10 istore_2
}
inc
11 iinc 3 by 1
14 iload_3
test 15 iload_1
16 if_icmplt -9 //7
19 iload_2
after
loop
20 ireturn

88. before
0 iconst_0
For Loop
init & test loop
1 istore_2
2 iload_1
static int sum( int min, int max ){ 3 istore_3
int sum = 0; 4 goto +10 //14
for ( int i=min; i<max; ++i ){ 7 iload_2
loop body
sum += i; 8 iload_3
} 9 iadd
return sum; 10 istore_2
}
inc
11 iinc 3 by 1
14 iload_3
test 15 iload_1
16 if_icmplt -9 //7
19 iload_2
after
loop
20 ireturn

89. before
0 iconst_0
For Loop
init & test loop
1 istore_2
2 iload_1
static int sum( int min, int max ){ 3 istore_3
int sum = 0; 4 goto +10 //14
for ( int i=min; i<max; ++i ){ 7 iload_2
loop body
sum += i; 8 iload_3
} 9 iadd
return sum; 10 istore_2
}
inc
11 iinc 3 by 1
14 iload_3
test 15 iload_1
16 if_icmplt -9 //7
19 iload_2
after
loop
20 ireturn

90. before
0 iconst_0
For Loop
init & test loop
1 istore_2
2 iload_1
static int sum( int min, int max ){ 3 istore_3
int sum = 0; 4 goto +10 //14
for ( int i=min; i<max; ++i ){ 7 iload_2
loop body
sum += i; 8 iload_3
} 9 iadd
return sum; 10 istore_2
}
inc
11 iinc 3 by 1
14 iload_3
test 15 iload_1
16 if_icmplt -9 //7
19 iload_2
after
loop
20 ireturn

91. before
0 iconst_0
For Loop
init & test loop
1 istore_2
2 iload_1
static int sum( int min, int max ){ 3 istore_3
int sum = 0; 4 goto +10 //14
for ( int i=min; i<max; ++i ){ 7 iload_2
loop body
sum += i; 8 iload_3
} 9 iadd
return sum; 10 istore_2
}
inc
11 iinc 3 by 1
14 iload_3
test 15 iload_1
16 if_icmplt -9 //7
19 iload_2
after
loop
20 ireturn

92. before
0 iconst_0
For Loop
init & test loop
1 istore_2
2 iload_1
static int sum( int min, int max ){ 3 istore_3
int sum = 0; 4 goto +10 //14
for ( int i=min; i<max; ++i ){ 7 iload_2
loop body
sum += i; 8 iload_3
} 9 iadd
return sum; 10 istore_2
}
inc
11 iinc 3 by 1
14 iload_3
test 15 iload_1
16 if_icmplt -9 //7
19 iload_2
after
loop
20 ireturn

93. Exception Handling
static int read( InputStream in ) {
try {
return in.read();
} catch ( IOException e ) {
return -1;
} finally {
IoUtils.closeQuietly( in );
}
}

94. 0 aload_0
Exception Handling 1 invokevirtual InputStream.read
try / finally
static int read( InputStream in ) { 4 istore_1
try { 5 aload_0
return in.read(); 6 invokestatic IoUtils.closeQuietly
} catch ( IOException e ) { 9 iload_1
return -1; 10 ireturn
} finally {
11 pop
IoUtils.closeQuietly( in );
catch / finally
12 aload_0
}
13 invokestatic IoUtils.closeQuietly
}
16 iconst_m1
17 ireturn
18 astore_2
19 aload_0
finally
20 invokestatic IoUtils.closeQuietly
23 aload_2
24 athrow

95. 0 aload_0
Exception Handling 1 invokevirtual InputStream.read
try / finally
static int read( InputStream in ) { 4 istore_1
try { 5 aload_0
return in.read(); 6 invokestatic IoUtils.closeQuietly
} catch ( IOException e ) { 9 iload_1
return -1; 10 ireturn
} finally {
11 pop
IoUtils.closeQuietly( in );
catch / finally
12 aload_0
}
13 invokestatic IoUtils.closeQuietly
}
16 iconst_m1
17 ireturn
18 astore_2
19 aload_0
finally
20 invokestatic IoUtils.closeQuietly
23 aload_2
24 athrow

96. 0 aload_0
Exception Handling 1 invokevirtual InputStream.read
try / finally
static int read( InputStream in ) { 4 istore_1
try { 5 aload_0
return in.read(); 6 invokestatic IoUtils.closeQuietly
} catch ( IOException e ) { 9 iload_1
return -1; 10 ireturn
} finally {
11 pop
IoUtils.closeQuietly( in );
catch / finally
12 aload_0
}
13 invokestatic IoUtils.closeQuietly
}
16 iconst_m1
17 ireturn
Exception Table
18 astore_2
start end handler Exception
19 aload_0
0 5 11 IOException
finally
20 invokestatic IoUtils.closeQuietly
0 5 18 any
23 aload_2
11 12 18 any 24 athrow

97. 0 aload_0
Exception Handling 1 invokevirtual InputStream.read
try / finally
static int read( InputStream in ) { 4 istore_1
try { 5 aload_0
return in.read(); 6 invokestatic IoUtils.closeQuietly
} catch ( IOException e ) { 9 iload_1
return -1; 10 ireturn
} finally {
11 pop
IoUtils.closeQuietly( in );
catch / finally
12 aload_0
}
13 invokestatic IoUtils.closeQuietly
}
16 iconst_m1
17 ireturn
Exception Table
18 astore_2
start end handler Exception
19 aload_0
0 5 11 IOException
finally
20 invokestatic IoUtils.closeQuietly
0 5 18 any
23 aload_2
11 12 18 any 24 athrow

98. More Attributes...
Java 1.2+
InnerClass
Synthetic
Deprecated

99. More Attributes...
Java 1.2+
InnerClass
Synthetic
Deprecated
Debugging
LineNumberTable
LocalVariableTable
SourceFile

100. More Attributes...
Java 1.2+ Java 5+
InnerClass Signature
Synthetic RuntimeVisibleAnnotations
Deprecated RuntimeInvisibleAnnotations
Debugging
LineNumberTable
LocalVariableTable
SourceFile

101. Byte Code Generation

102. Resources
The Java Virtual Machine Specification
http://java.sun.com/docs/books/jvms/
JClassLib Viewer
http://www.ej-technologies.com/products/jclasslib/
overview.html
Maxine VM
http://labs.oracle.com/projects/maxine/
New Features in Java 6 - Annotation Processing
http://www.javabeat.net/articles/14-java-60-features-
part-2-pluggable-annotation-proce-1.html