Package org.plumelib.reflection
Class ReflectionPlume
- java.lang.Object
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- org.plumelib.reflection.ReflectionPlume
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public final class ReflectionPlume extends java.lang.Object
Utility functions related to reflection, Class, Method, ClassLoader, and classpath.
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static void
addToClasspath(java.lang.String dir)
Add the directory to the system classpath.static java.lang.Class<?>
classForName(@ClassGetName java.lang.String className)
LikeClass.forName(String)
: given a string representing a non-array class, returns the Class.static java.lang.String
classpathToString()
Returns the classpath as a multi-line string.static java.lang.Class<?>
defineClassFromFile(@BinaryName java.lang.String className, java.lang.String pathname)
Converts the bytes in a file into an instance of class Class, and resolves (links) the class.static @ClassGetSimpleName java.lang.String
fullyQualifiedNameToSimpleName(@FullyQualifiedName java.lang.String qualifiedName)
Returns the simple unqualified class name that corresponds to the specified fully qualified name.static @Nullable java.lang.Object
getPrivateField(java.lang.Object o, java.lang.String fieldName)
Reads the given field, which may be private.static boolean
isSubtype(java.lang.Class<?> sub, java.lang.Class<?> sup)
Return true iff sub is a subtype of sup.static <T> @Nullable java.lang.Class<T>
leastUpperBound(@PolyMustCall @PolyNull java.lang.Object[] objects)
Returns the least upper bound of the classes of the given objects.static <T> @Nullable java.lang.Class<T>
leastUpperBound(@Nullable java.lang.Class<T>[] classes)
Returns the least upper bound of all the given classes.static <T> @Nullable java.lang.Class<T>
leastUpperBound(@Nullable java.lang.Class<T> a, @Nullable java.lang.Class<T> b)
Returns the least upper bound of the given classes.static <T> @Nullable java.lang.Class<T>
leastUpperBound(java.util.List<? extends @Nullable java.lang.Object> objects)
Returns the least upper bound of the classes of the given objects.static java.lang.reflect.Method
methodForName(@BinaryName java.lang.String classname, java.lang.String methodname, java.lang.Class<?>[] params)
Given a class name and a method name in that class, return the method.static java.lang.reflect.Method
methodForName(java.lang.String method)
Given a method signature, return the method.static java.lang.String
nameWithoutPackage(java.lang.Class<?> c)
Returns the class name, including outer classes but without the package.static void
setFinalField(java.lang.Object o, java.lang.String fieldName, @Interned java.lang.Object value)
Sets the given field, which may be final and/or private.
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Method Detail
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isSubtype
@Pure public static boolean isSubtype(java.lang.Class<?> sub, java.lang.Class<?> sup)
Return true iff sub is a subtype of sup. If sub == sup, then sub is considered a subtype of sub and this method returns true.- Parameters:
sub
- class to test for being a subtypesup
- class to test for being a supertype- Returns:
- true iff sub is a subtype of sup
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classForName
public static java.lang.Class<?> classForName(@ClassGetName java.lang.String className) throws java.lang.ClassNotFoundException
LikeClass.forName(String)
: given a string representing a non-array class, returns the Class. UnlikeClass.forName(String)
, the argument may be a primitive type or a fully-qualified name (in addition to a binary name).If the given name can't be found, this method changes the last '.' to a dollar sign ($) and tries again. This accounts for inner classes that are incorrectly passed in in fully-qualified format instead of binary format. (It should try multiple dollar signs, not just at the last position.)
Recall the rather odd specification for
Class.forName(String)
: the argument is a binary name for non-arrays, but a field descriptor for arrays. This method uses the same rules, but additionally handles primitive types and, for non-arrays, fully-qualified names.- Parameters:
className
- name of the class- Returns:
- the Class corresponding to className
- Throws:
java.lang.ClassNotFoundException
- if the class is not found
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fullyQualifiedNameToSimpleName
public static @ClassGetSimpleName java.lang.String fullyQualifiedNameToSimpleName(@FullyQualifiedName java.lang.String qualifiedName)
Returns the simple unqualified class name that corresponds to the specified fully qualified name. For example, if qualifiedName is java.lang.String, String will be returned.- Parameters:
qualifiedName
- the fully-qualified name of a class- Returns:
- the simple unqualified name of the class
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nameWithoutPackage
public static java.lang.String nameWithoutPackage(java.lang.Class<?> c)
Returns the class name, including outer classes but without the package. Uses "." as the separator between outer an inner classes, as in Java source code.- Parameters:
c
- a class- Returns:
- the class name, including outer classes but without the package
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defineClassFromFile
public static java.lang.Class<?> defineClassFromFile(@BinaryName java.lang.String className, java.lang.String pathname) throws java.io.FileNotFoundException, java.io.IOException
Converts the bytes in a file into an instance of class Class, and resolves (links) the class. LikeClassLoader.defineClass(String,byte[],int,int)
, but takes a file name rather than an array of bytes as an argument, and also resolves (links) the class.- Parameters:
className
- the name of the class to define, or null if not knownpathname
- the pathname of a .class file- Returns:
- a Java Object corresponding to the Class defined in the .class file
- Throws:
java.io.FileNotFoundException
- if the file cannot be foundjava.io.IOException
- if there is trouble reading the file- See Also:
ClassLoader.defineClass(String,byte[],int,int)
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addToClasspath
public static void addToClasspath(java.lang.String dir)
Add the directory to the system classpath.- Parameters:
dir
- directory to add to the system classpath
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classpathToString
public static java.lang.String classpathToString()
Returns the classpath as a multi-line string.- Returns:
- the classpath as a multi-line string
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methodForName
public static java.lang.reflect.Method methodForName(java.lang.String method) throws java.lang.ClassNotFoundException, java.lang.NoSuchMethodException, java.lang.SecurityException
Given a method signature, return the method.Example calls are:
UtilPlume.methodForName( "org.plumelib.reflection.ReflectionPlume.methodForName" +"(java.lang.String, java.lang.String, java.lang.Class[])") UtilPlume.methodForName("org.plumelib.reflection.ReflectionPlume.methodForName" +"(java.lang.String,java.lang.String,java.lang.Class[])") UtilPlume.methodForName("java.lang.Math.min(int,int)")
- Parameters:
method
- a method signature- Returns:
- the method corresponding to the given signature
- Throws:
java.lang.ClassNotFoundException
- if the class is not foundjava.lang.NoSuchMethodException
- if the method is not foundjava.lang.SecurityException
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methodForName
public static java.lang.reflect.Method methodForName(@BinaryName java.lang.String classname, java.lang.String methodname, java.lang.Class<?>[] params) throws java.lang.ClassNotFoundException, java.lang.NoSuchMethodException, java.lang.SecurityException
Given a class name and a method name in that class, return the method.- Parameters:
classname
- class in which to find the methodmethodname
- the method nameparams
- the parameters of the method- Returns:
- the method named classname.methodname with parameters params
- Throws:
java.lang.ClassNotFoundException
- if the class is not foundjava.lang.NoSuchMethodException
- if the method is not foundjava.lang.SecurityException
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setFinalField
public static void setFinalField(java.lang.Object o, java.lang.String fieldName, @Interned java.lang.Object value) throws java.lang.NoSuchFieldException
Sets the given field, which may be final and/or private. Leaves the field accessible.- Parameters:
o
- object in which to set the field; null iff the field is staticfieldName
- name of field to setvalue
- new value of field; may be null iff the field is nullable- Throws:
java.lang.NoSuchFieldException
- if the field does not exist in the object
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getPrivateField
public static @Nullable java.lang.Object getPrivateField(java.lang.Object o, java.lang.String fieldName) throws java.lang.NoSuchFieldException
Reads the given field, which may be private. Leaves the field accessible. Use with care!- Parameters:
o
- object in which to set the fieldfieldName
- name of field to set- Returns:
- new value of field
- Throws:
java.lang.NoSuchFieldException
- if the field does not exist in the object
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leastUpperBound
public static <T> @Nullable java.lang.Class<T> leastUpperBound(@Nullable java.lang.Class<T> a, @Nullable java.lang.Class<T> b)
Returns the least upper bound of the given classes.- Type Parameters:
T
- the (inferred) least upper bound of the two arguments- Parameters:
a
- a classb
- a class- Returns:
- the least upper bound of the two classes, or null if both are null
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leastUpperBound
public static <T> @Nullable java.lang.Class<T> leastUpperBound(@Nullable java.lang.Class<T>[] classes)
Returns the least upper bound of all the given classes.- Type Parameters:
T
- the (inferred) least upper bound of the arguments- Parameters:
classes
- a non-empty list of classes- Returns:
- the least upper bound of all the given classes
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leastUpperBound
public static <T> @Nullable java.lang.Class<T> leastUpperBound(@PolyMustCall @PolyNull java.lang.Object[] objects)
Returns the least upper bound of the classes of the given objects.- Type Parameters:
T
- the (inferred) least upper bound of the arguments- Parameters:
objects
- a list of objects- Returns:
- the least upper bound of the classes of the given objects, or null if all arguments are null
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leastUpperBound
public static <T> @Nullable java.lang.Class<T> leastUpperBound(java.util.List<? extends @Nullable java.lang.Object> objects)
Returns the least upper bound of the classes of the given objects.- Type Parameters:
T
- the (inferred) least upper bound of the arguments- Parameters:
objects
- a non-empty list of objects- Returns:
- the least upper bound of the classes of the given objects, or null if all arguments are null
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