?.?.?. ???????? ?.?. (email: [e-mail])

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????????-??????????????? ?????? ?
????????????????
?????? 8. ?????????? ? ?????
?.?.?. ???????? ?.?. (email egrinkrug_at_hse.ru)
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Runtime Type Information

• ???????? ????????? ? ????????????? ?????????? ?
  ????? ?? ????? ?????????? ????????? ??????
  ???????? ???.
• ?????????? ??????
• ??????????? ????? Shape c ??????? draw()
• ??? ?????????? ??????????? ?????? (?.?. ? ??????
  ?????????????)

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?????? ??????????
4
??? ??? ????????? ??? ????? ?????????

• ??? ????? Shape ?? ????? ?????????????????
• ????? draw() ???????? ?????? Shape ??????
  ?????????? ????? toString() ??? ?????? ????????
  ?????????? ??????
• ??? ????? ?????? System.out.println() ??????????
  ?????? this
• ????? toString() ? Shape ???????????. ??
• ?????????????? ????? toString() ??
  java.lang.Object
• ????????? ??????????? ?? Shape ?????? ??????????
  toString().
• ????? this ??????????? ? ????????? ????????????
  ?????, ????????????? ?????????? ??? toString()
• ??? ????????? ??????????? ?????????? ???? ?
  ?????? ??????????? ???? ?????????? ??????????
  ?????????????? ???? ?????? ?????? ?????? ???????
  Shape.
• ????? ???????? ??????????? ??? ?????? ??????
  ?????????? ?? ????? draw() ? ?? ????? toString()
• ????????? ?????????
• Circle.draw()
• Square.draw()
• Triangle.draw()
• ??? ????, ???? ???-???? ??????? ??????, ? ?????
  ????? ????? Shape ?? ???????? (????????, ?????
  ????????? ???????????? ? ??????? ????)? ???
  ?????? ??? ???????, ???? ?????? ???????? ?????

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?????? Class

• ?????? ?????, ??????????????? ? ?????????,
  ??????????? ????? ???????? Class
• ??? ????????? ? ?????????? ?????? ?????? ??? ????
  ????????? ?????? Class, ??????? ??????????? ?
  ??????????? ????? ? ??????????? .class
• ???? ?????? ??????????? ??????????? ???????
  (ClassLoader??)
• ???????? ??????? ????? ??????????? ???????
  ???????????? ??????????? ???????, ??????? ?????
  ?????????????? ??????????? ?????????
• ???????? (????????) ????????? ???????? ??????
  ?????????? JVM
• ?????? ???? ????????? ????????? ??????????
  ??????, ??????? Java API, ? ?????????? ?????
• ?????????????? ?????????? ??????? ?????
  ?????????? ?????? ? ???-???????, ?? ???? ??? ????
  ???????? ???????? ?? ?? ????...
• ??? ?????? ??????????? ? JVM ???????????, ???
  ?????? ?????????????
• ??????????? ????-??? ??????????? JVM ??
  ????????????.

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?????? Class

• ?????? Class ??? ???? ??????, ??????????????
  ???????, ? ??????? ????? ?????????????? ?
  ?????????, ?????????? ??????? ?? ????.
• ?????? ?????? ????? ????? ?? ??????
  java.lang.Object
• public final Class getClass()
• ?????????? ????? ?? ????? ??????? (?????,
  ????????? ?????? ??????)
• ?????? ?????? ???????? ? ?? ????? ????
  ?????????????????
• ????????
• void myMethod ( Object parameter )
• Class parameterClass parameter.getClass()
  //
• - ????????? getClass() ??? ????????? ??????
  ???????????? ????????? ?? ????? ?????????? (at
  runtime)...

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????? Class

• ??? ??????? Class ??????????? public final ??????
  Class
• Object ? new Object() // ??? new
  Tri?ngle(), ? ?.?. ? ?.?.
• Class oc o.getClass() // ???
  ?????? ???? ?????????? ?????? Class !!!
• Class cc oc.getClass() // ? ???
  ????? ?lass ??? ???? ????? !!!
• (cc.getClass() cc) --gt true // ??? ?????
  ??? ?? ??? !!!
• ????? Class ??? ?????????, ????????????
  ????????, ??????? ????? ??????????? ? ?????????
  Class (??? ?????? - ?????? ???????? ? C ?)
• ??? ? ??? ????? ????????, ???? ?????? ?? ??????,
  ????? ????????? ??? ???? ???????? ????????,
  ???????????? ? ?????? ??????? (?.?.
  ???????-?????)
• ???? ?????? ?? ?????????? ?????, ????? ????????
  (?????????????) ?????? ?????? Class ??? ???????
  ??????????? ??????.
• ??? ? ????? ?????, ????? Class ????? ???????????
  ??????, ?? ????????? ??????? ?????????? (???????
  Class) ??? ?? ??????.
• C????? ? ???????? ?????????? ??????? ?????? Class
  ???????? ??????? ?????????? ?????????
  ????????-???????????????? ???????????????? ?
  Java, ?????? ? ???????? ?????? Object.

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???????? ?????? ?????? Class

• ????? ?????? Class ???????? immutable-????????
  (??? ??? ?????????) ??? ?????? ?????? Class
  ???????? ?????????? ?? ???????? Class??, ? ??
  ?????? ??.
• ????????? ????? ??????
• String getName () // ???? ?????? ??? ?????? (?
  jdk 1.0)
• ????????, com.grinkrug.rtti.Triangle
• String getSimpleName () // ???? ???????? ???
  ?????? (c jdk1.5)
• ????????, Triangle
• String getCanonicalName () // ???? ????????????
  ??? ?????? (? jdk1.5)
• ????????, com.grinkrug.rtti.Triangle
• ? ??????? ?? getName() ?????????? ?????? ?????
  ????????? ??????? ????? . (?????), ? ?? ????
  , null ??? ????????? ? ?????????
  ???????...(???????? ?? ?????????? ??? ???????? ?
  ?????? ?????????? ???????, ??????? ????????? ?
  ?????????!)

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??? ??? ?? ?????????? ???????

• ?????? ??? top-level ?????? / ?????????? ???
  ??? ????????????? ??? ?????? ?om.grinkrug.rtti.T
  riangle
• ?????? ??? ???????????? ???? ???
  ??????????????? ???????? ?????
• 
  int, byte, float
• ??????????? ??? ?????? ??????? ?????????????? ???
  ??????? (?????????? ?? ?????? ??????????????
  ??????????? ???????) ??? ???? ?????????,
• ??? ??????????? ???? ????????? ??????????
  ?????????, ? ????????? ???????? L lt??? ????gt
  
• ???????? F ????????? ?????? float ?
  Ljava.lang.Object ?????? Object??.
• ???????????? ????? ????????? ? jdk1.5(), ???
  ???????? ?????, ?? ?? ???????? ?????? ?????
  (fully qualified names) ?? ??????? jdk.

boolean Z float F byte
B int I char
C long J double
D short S ????? ???
????????? L
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• ????????? ?????? ?? ????? (static - ?????)
• public static Class forName ( String className )
• 
  throws ?lassNotFoundException
• ???????? ??? ???? ?????? ??? ?????????? ??????
  (fully qualified name)
• ?????????? ?????? ?? ?????? Class,
  ??????????????? ?????????? ????? (?????????
  ?????? ????? ??? ?????????????, ?? ????? ???????,
  ??????? ??? ????...).
• ????????? ?????? ?? ?????-????????
• ???? ?????? ????? ?????????? ????????, ?????? ??
  ???? ????? ???????? ?? ?????-???????? Class c
  Triangle.class
• ???????????? ???????????? ??? (? ??????? ?? fully
  qualified name ??? ?????? forName())
  Object.class
• ????????? ?????? ?????????????? ???????????? (?
  ?? ? ????????, ??? ?????? ??????) ? ?????????????
  ????????????? ?? ??????? ????????????? ?????? ???
  ?????????? ??? ????? ?????.
• ? Java ??? ??????????? ??????????????? ?????, ??
  ???? ??????????????? ????? ???????????? ??
  ???????, ? ?? ???, ??? ??? ????? ?????????, ?.?.
  ????????? ??? ?????????. ???????, ????? ?????
  ?????.

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?????? ?????? ?lass ??? ??????? ???????????????
??????? ?????? ??????? Class ????? ??????
??????????? ???, ??? ????? ????????????? ????? ?
????.

• ???????? ?? ?????? ????? ????????????
• public boolean isInterface ( )
• ???????? ?? ?????? ????? ??????? ????????
• public boolean isArray ( )
• - ? ???? ????????, ??
• public Class getComponentType ( )
• ???????? ?? ????? ????? Enum-???
• public boolean isEnum ( )
• ???????????? ?? ?????? ????? ??????????? ????
• public boolean isPrimitive ( )
• ???????? ?? ????? ????? ??????????
• public boolean isAnonimousClass ( )
• ???????? ?? ????? ????? ??????????
• public boolean isLocalClass()
• ???????? ?? ????? ????? ???????-??????
  (?????????)
• public boolean isMemberClass ( )
• ????? ????? ???????????? ?????? ??????
• public Class getDeclaringClass ( )

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• ????? ?????????? ??????????? ?????? ??????? ???
  ????????????
• public Class getInterfaces()
• ????? ?????????? ? ??????? ???????
• public Class getSuperclass()
• ???????????? ?? ?????? ????? ?????????? /
  ?????????????? ????????
• public boolean isAssignableFrom (Class
  another)
• ????? ??????????? ??????? ??? ??????? ??????
  ??????
• public ClassLoader getClassLaoder()
• ?????? ?????? ??????????? ?????? ??????
• public Package getPackage()
• ???????? ?? ?????????? ?????? ????????? ???????
  ???????
• public boolean isInstance(Object o)
• ??? ???????????? ?????????? ?????????
  instanceof
• if(shape instanceof Triangle )
• Triangle t (Triangle)shape
• ????????? ??????, ????? ????? ????? ????????????
  ?????????? ? ??? ?? ???? ?????????? ?????
  isInstance() ? ???????? instanceof ?

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Reflection ???????????? ?????? ? ???????

• ??? ????, ???? ?? ????? ???????? ? ?????
  ????????
• ?? ????? ?????????, ??????? ???????? ? ??????????
  ????????
• ??? ???????? ?????-?? ?????? (??? ?????????
  ????), ? ??????? ??????????? ??.
• ??? ???????? ???????? ??? ?????????????
  ????????????????
• ???-?? ?????? ?????????? ??????? ??????????
• ?? ?????????? ?? ?? ???? ???????????, ???
  ?????? ?????? ???????, ??? ??????????, ??? ????
  (?.?. ??? ?????????????? ??????)
• ???????? ?????????????? ????? ???? ??????? ? ??
  ?????? ???????????????? (????????)
  ??????????????
• ??? ????????? ??????? ??????? (Remote Method
  Invocation, RMI), ??? ?? ????? ???????? ?
  ???????? ?? ?????? ??????, ??? ?????????????
  ??????? ?? ????? ??? ?????????? ????? ?????????.
• ??? ????????????? ???????????? / ??????????????
  ????????, ?. ??.

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????? Class ? reflection

• ????? Class ???????????? ????????? Reflection
  (??? ? ?????????)
• ?????????????? ????????? ?????????????? ???????
  java.lang.reflect.
• ? ?????????? java.lang.reflect ???? ??????,
  ??????? ??????? ????????? JVM ??? ????????????
  ?????? ?????? ? ???????? ?????????? ?????????.
  ????????? ?? ??? ????????
• Constructor
• Method
• Field
• ????? Class ????? ??????, ??????????? ????????
  ??? ??????? ??? ????????? ?????????? ?????? ?
  ???????????? ?? ? ????????. ????? ????, ? ?????
  ?????? Class ???? ?????? ??? ??????? ???
  ????????? ???????, ? ?.?.

15
?????????? ?????????? ? ?????????????
??????(??????????? ?????? ??????? ?????? Class)

• ????????? ???? public ????????????? ??????
• public Constructor getConstructors ( )
  throws SecurityException
• ????????? ???? ????????????? ?????? (???????
  ?????????)
• public Constructor getDeclaredConstructors (
  ) throws SecurityException
• ????????? ????????? public - ???????????? ??????
• public Constructor getConstructor (Class
  paramTypes)
• throws NoSuchMethodException,
  SecurityException
• ????????? ????????? ????????????,
  ???????????????? ? ??????
• public Constructor getDeclaredConstructor
  (Class paramTypes)
• throws NoSuchMethodException,
  SecurityException

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???????????????? ??????

• ????????? ????? ??? ????? ????????? ????
  ?????????? (??? ??????? ???????????? ???
  ??????????)
• public Object newInstance() throws
  InstantiationException,IllegalAccessException

• ?????? ??????????? (java.lang.reflect.Constructor)
  ?????????
• ????????? ?????????? ?????? (?????? ??? ???
  ?????? ???????????), ?.?. -???? ??????????,
  ??????????, ...
• ????????? ???????? ? ????????????? ?????? ???????
  ??????, ???????? ??????????? ??????????? (??????,
  ??? ??????????? ??? ????????????), ? ?????????
  ??????????? ????????

static Object createInstance(Constructor c,
Object params) throws Exception
return c.newInstance(params)
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?????????? ?????????? ? ???????
??????(??????????? ?????? ??????? ?????? Class)

• ????????? ???? public ??????? ??????
• public Method getMethods ( ) throws
  SecurityException
• ????????? ???? ??????? ?????? (??????? ?????????,
  ?? ???????? ??? ??????????????)
• public Method getDeclaredMethods ( ) throws
  SecurityException
• ????????? ????????? public - ?????? ??????
• public Method getMethod (String name, Class
  paramTypes)
• throws NoSuchMethodException,
  SecurityException
• ????????? ????????? ??????, ???????????????? ?
  ??????
• public Method getDeclaredMethod (String name,
  Class paramTypes)
• throws NoSuchMethodException,
  SecurityException

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????????????? ??????? Method

• ??? ? ?????? Constructor, ?????? Method ?????
  ???????? ?????????? ? ???? (???? ??????????,
  ????????????? ????????, ????????? ?? ??
  ?????????? ????? ???????????, ? ??.)
• ???????? ?????????? ???????????? ??????? Method
  ???????? ?????? ??????
• ????????

public Object invoke (Object obj, Object
args) throws IllegalAccessException,
AllegalArgumentException, InvocationTargetExc
eption
static Object callMethod (Object o, Method m,
Objectparams) throws Exception return
m.invoke (o, params)
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?????? ? ?????? ??????(??????????? ??????
??????? ?????? Class)

• ????????? ???? public ????? ??????
• public Field getFields ( ) throws
  SecurityException
• ????????? ???? ????? ?????? (??????? ?????????,
  ?? ???????? ??? ??????????????)
• public Field getDeclaredFields ( ) throws
  SecurityException
• ????????? ????????? public - ???? ?????? ??
  ?????
• public Field getField (String name)
• throws NoSuchFieldException,
  SecurityException
• ????????? ????????? ????, ???????????????? ?
  ?????? ??????
• public Field getDeclaredField (String name)
• throws NoSuchFieldException,
  SecurityException

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?????? ? ?????? ??????

• ????? Field ???????????? ??? ??????? ? ????????
  ???? ?????? ? ??????????? ???????
• ???? ???? ? ?????? ???????????, ?? ??????????
  ?????? ? ???????? ??????? ???????????? ? ?????
  ???? null
• ??? ??????? ? ???????? ???? ? ?????? Field ????
  ????? ???????
• ??????
• public Object get (Object concreteObject)
• throws
  IllegalArgumentException, IllegalAccessExpublictio
  n
• public int getInt (Object concreteObject)
• throws IllegalArgumentException,
  IllegalAccessExpubliction
• // ? ??? ?????? ??????????? ?????
• ? ??????
• public void set (Object concreteObject, Object
  newValue)
• throws IllegalArgumentException,
  IllegalAccessExpubliction
• public void setInt (Object concreteObject, int
  newValue)
• throws IllegalArgumentExcep
  tion, IllegalAccessExpubliction
• // ? ??? ????? ??????????? ?????

21
Reflection ? ???????

• ? ?????????? reflection ???? ????????? ????? ???
  ????????????? ???????? ???????? ? ??????? ? ???
  java.lang.reflect.Array.
• ? ???? ??????
• ????????? ???????? ???????
• public static Object newInstance(Class
  componentType, int length)
• throws NegativeArraySizeException
• public static Object newInstance(Class
  componentType, int dimensions)
• throws IllegalArgumentException,
  NegativeArraySizeException
• ???????? ?????? ? ????????? ???????
• public static Object get (Object array, int
  index)
• throws IllegalArgumentException,
  ArrayIndexOutOfBoundsException
• public static void set (Object array, int index,
  Object newValue)
• throws IllegalArgumentException,
  ArrayIndexOutOfBoundsException
• ? ?? ??????? ??? ??????????? ????? ?????????
  ???????...
• ??? ????? ????????? ??????? ???????????? ?????? ?
  ??????????

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?????????? ???????????? ??????? reflection

• ??? ?????????? ???????? ??????? ??????????
• ??? ???????????? ???????, ??? ????????????? ??
  runtime
• ??? ?????? (??? ??????????? ???????????? ???????)
  ?? ????????? ? ????????? ????? (????????? ???!)
• ???????????? ?????? ?????????? ????????? (????
  ???? ?????? ?????????? ????????? ??????????????)

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?????????????????? reflection

• ? ?????????? ????? ??????? ? JDK 5() ?????????
  ??????????????? ?????????? ? reflection-??????????
  ? ? ????? ?????? Class
• ??? ???????? ????? ???????? ??????????? ? ??????
  ? ??????, ???????????? ? Java
• ?? ?????????? ????? ?????????????????? ? ????????
  reflection ??? ??? ? ??????????.

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QA