Java Virtual Machine's Internal Architecture
Content
11/18/2010
Java Virtual Machine's Internal Archite…
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main() main() void String main() // On CD-ROM in file jvm/ex1/Echo.java class Echo { }
public static void main(String[] args) { int len = args.length; for (int i = 0; i < len; ++i) { System.out.print(args[i] + " "); } System.out.println(); }
main() java Echo java java Echo Greetings, Planet.
java Echo Echo main() void String Greetings, Planet. main() String String Echo arg[0] "Greetings," arg[1] "Planet." main() main() exit() Runtime System Echo main() artima.com/insidejvm/ed2/jvmP.html
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main()
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boolean int byte boolean false true boolean int boolean byte byte boolean byte short int long char float double long returnAddress finally returnAddress reference reference null reference byte
short int
long
char
float double
returnAddress artima.com/insidejvm/ed2/jvmP.html
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reference
null
byte short int char float returnAddress reference long double
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java.lang java.lang.ClassLoader ClassLoader java.lang.Class Г Class
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Г Г Г Г
Г CLASSPATH CLASSPATH .class CLASSPATH java.lang.Object Object.class java\lang CLASSPATH CLASSPATH Г
Г ClassLoader artima.com/insidejvm/ed2/jvmP.html
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// Four of the methods declared in class java.lang.ClassLoader: protected final Class defineClass(String name, byte data[], int offset, int length); protected final Class defineClass(String name, byte data[], int offset, int length, ProtectionDomain protectionDomain); protected final Class findSystemClass(String name); protected final void resolveClass(Class c);
ClassLoader defineClass() byte data[] length ClassLoader offset name defineClass() protectionDomain defineClass() ClassLoader findSystemClass() String Class ClassNotFoundException findSystemClass() findSystemClass() resolveClass() Class Class defineClass() Г Г defineClass() Class resolveClass() ClassLoader Г
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Г
Lava Lava Г artima.com/insidejvm/ed2/jvmP.html
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java.lang.Object public abstract final Object java.lang java.lang.Object java/lang/Object
ClassLoader Class
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public private protected static final volatile transient
void public private protected static final synchronized native abstract
ClassLoader artima.com/insidejvm/ed2/jvmP.html
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Class java.lang.Class Class Class Class Class // A method declared in class java.lang.Class: public static Class forName(String className);
forName("java.lang.Object") Class java.lang.Object forName("java.util.Enumeration") Class Enumeration java.util forName() Class ClassNotFoundException forName() Class getClass() Object // A method declared in class java.lang.Object: public final Class getClass();
java.lang.Integer Class java.lang.Integer getClass() Integer Class Class Class Class // Some of the methods declared in class java.lang.Class: public String getName(); public Class getSuperClass(); public boolean isInterface(); public Class[] getInterfaces(); public ClassLoader getClassLoader();
getName() getSuperClass() Class java.lang.Object getSuperClass() null isInterface() true Class false getInterfaces() Class getInterfaces() getClassLoader() artima.com/insidejvm/ed2/jvmP.html
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ClassLoader null
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// On Lava CD-ROM class { in file jvm/ex2/Lava.java
private int speed = 5; // 5 kilometers per hour
}
void flow() { }
// On CD-ROM in file jvm/ex2/Volcano.java class Volcano { }
public static void main(String[] args) { Lava lava = new Lava(); lava.flow(); }
main() Volcano Volcano main() Volcano Volcano Volcano Volcano.class Volcano main() main() Volcano main() Volcano Lava Г artima.com/insidejvm/ed2/jvmP.html
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main() main() Volcano Lava Lava
"Lava" forName() Class Class Lava Lava.class Lava Volcano "Lava" Lava Volcano Lava "Lava" Lava Lava Volcano Lava Lava Lava speed Lava Object Г main() Lava speed flow() Lava artima.com/insidejvm/ed2/jvmP.html
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OutOfMemory artima.com/insidejvm/ed2/jvmP.html
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instanceof artima.com/insidejvm/ed2/jvmP.html
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Г Object wait() notify() notifyAll() artima.com/insidejvm/ed2/jvmP.html
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Г Class int int int "[I" byte "[[[B" Object "[[Ljava.lang.Object" int int
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Object
returnAddress
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Г
Г int float reference returnAddress byte short char int long double artima.com/insidejvm/ed2/jvmP.html
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long long long double // On CD-ROM in file jvm/ex3/Example3a.java class Example3a {
public static int runClassMethod(int i, long l, float f, double d, Object o, byte b) {
return 0; }
public int runInstanceMethod(char c, double d, short s, boolean b) {
}
}
return 0;
runInstanceMethod() reference this artima.com/insidejvm/ed2/jvmP.html
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runClassMethod() this byte short char boolean int boolean int boolean byte short char
byte short char int int byte short char Object o runClassMethod() i j Example3b j i i j // On CD-ROM in file jvm/ex3/Example3b.java class Example3b {
public static void runtwoLoops() {
for (int i = 0; i < 10; ++i) { System.out.println(i); }
}
for (int j = 9; j >= 0; --j) { System.out.println(j); } }
long double
Г
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int long float double reference returnType byte short char int iadd int int int int iload_0 iload_1 iadd istore_2
// // // //
push the int in local variable 0 push the int in local variable 1 pop two ints, add them, push result pop int, store into local variable 2
iload_0 iload_1 int iadd int int istore_2
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int long float double String
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// On CD-ROM in file jvm/ex3/Example3c.java class Example3c {
public static void addAndPrint() { double result = addTwoTypes(1, 88.88); System.out.println(result); }
}
public static double addTwoTypes(int i, double d) { return i + d; }
addAndPrint() addTwoTypes() addAndPrint() int double addTwoTypes()
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addTwoTypes() addAndPrint() addTwoTypes() Г addTwoTypes() addTwoTypes() javac addTwoTypes() addTwoTypes() double int addAndPrint() addTwoType() addTwoTypes() double addAndPrint() double addAndPrint() addTwoType()
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addAndPrint() addAndPrint() addTwoType() addAndPrint() addTwoType()
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goto return athrow throw athrow ArithmeticException idiv ldiv irem lrem int long doMathForever() // On CD-ROM in file jvm/ex4/Act.java class Act { }
public static void doMathForever() { int i = 0; for (;;) { i += 1; i *= 2; } }
doMathForever() // // // // // //
Bytecode stream: 03 3b 84 00 01 1a 05 68 3b a7 ff f9 Disassembly: Method void doMathForever() Left column: offset of instruction from beginning of method | Center column: instruction mnemonic and any operands | | Right column: comment 0 iconst_0 // 03 1 istore_0 // 3b 2 iinc 0, 1 // 84 00 01
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5 6 7 8 9
iload_0 iconst_2 imul istore_0 goto 2
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// // // // //
1a 05 68 3b a7 ff f9
javap javap goto iinc iinc goto -7 goto 2 iinc .o .obj
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istore int fstore float int float
int float dup goto arraylength instanceof arraylength instanceof
byte
b
baload byte
short
s
saload short
int long
i l
iaload int laload long
char
c
caload char
float
f
faload float
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double
d
daload double
reference a
aaload reference
int long float int double reference dup int float reference returnAddress dup long double long double dup2 byte short char int int byte short char
byte
int
short
int
int
int
long
long
char
int
float
double
reference
float double reference
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Г
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Г wait() notify() notifyAll() Object Г long double
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int long double volatile long long double long double long double long double long double
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Г Г
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applets/EternalMath.html doMathForever() Act iconst_0 iconst_0 doMathForever() i iconst_0 istore_0
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iinc i i += 1 doMathForever() iload_0 iconst_2 int imul ints istore_0 i *= 2 doMathForever() goto iinc goto for (;;) doMathForever()
jvm applets/EternalMath.html applets/JVMSimulators applets/JVMSi applets/JVMSimulators/COM/ mulators/COM/artima/jvmsim artima/jvmsim
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http://www.artima.com/insid http://www.art ima.com/insidejvm/resources ejvm/resources/ /
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