Package org.plumelib.reflection

Class ReflectionP

java.lang.Object
org.plumelib.reflection.ReflectionP
public final class ReflectionP extends Object
Utility functions related to reflection, Class, Method, ClassLoader, and classpath.

  • Method Details

    • isSubtype

      @Pure public static boolean isSubtype(Class<?> sub, Class<?> sup)
      Returns true iff sub is a subtype of sup. If sub == sup, then sub is considered a subtype of sup and this method returns true.
      Parameters:
      sub - class to test for being a subtype
      sup - class to test for being a supertype
      Returns:
      true iff sub is a subtype of sup

    • classForName

      public static Class<?> classForName(@ClassGetName String className) throws ClassNotFoundException
      Like Class.forName(String): given a string representing a non-array class, returns the Class. Unlike Class.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, repeating with successive dots (from right to left) until the class is found or no dots remain. This accounts for inner classes that are incorrectly passed in fully-qualified format instead of binary format.

      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:
      ClassNotFoundException - if the class is not found

    • fullyQualifiedNameToSimpleName

      public static @ClassGetSimpleName String fullyQualifiedNameToSimpleName(@FullyQualifiedName 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

    • nameWithoutPackage

      public static String nameWithoutPackage(Class<?> c)
      Returns the class name, including outer classes but without the package. Uses "." as the separator between outer and inner classes, as in Java source code.
      Parameters:
      c - a class
      Returns:
      the class name, including outer classes but without the package

    • defineClassFromFile

      public static Class<?> defineClassFromFile(@BinaryName String className, String pathname) throws FileNotFoundException, IOException
      Converts the bytes in a file into an instance of class Class, and resolves (links) the class. Like ClassLoader.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 known
      pathname - the pathname of a .class file
      Returns:
      a Java Object corresponding to the Class defined in the .class file
      Throws:
      FileNotFoundException - if the file cannot be found
      IOException - if there is trouble reading the file
      See Also:

    • addToClasspath

      public static void addToClasspath(String dir)
      Add the directory to the system classpath.
      Parameters:
      dir - directory to add to the system classpath

    • classpathToString

      public static String classpathToString()
      Returns the classpath as a multi-line string.
      Returns:
      the classpath as a multi-line string

    • methodForName

      public static Method methodForName(String method) throws ClassNotFoundException, NoSuchMethodException
      Given a method signature, return the method.

      Example calls are: 

       UtilP.methodForName(
   "org.plumelib.reflection.ReflectionP.methodForName"
   +"(java.lang.String, java.lang.String, java.lang.Class[])")
 UtilP.methodForName("org.plumelib.reflection.ReflectionP.methodForName"
                         +"(java.lang.String,java.lang.String,java.lang.Class[])")
 UtilP.methodForName("java.lang.Math.min(int,int)")
      Parameters:
      method - a method signature
      Returns:
      the method corresponding to the given signature
      Throws:
      ClassNotFoundException - if the class is not found
      NoSuchMethodException - if the method is not found

    • methodForName

      public static Method methodForName(@BinaryName String classname, String methodname, Class<?>[] params) throws ClassNotFoundException, NoSuchMethodException
      Given a class name and a method name in that class, return the method.
      Parameters:
      classname - class in which to find the method
      methodname - the method name
      params - the parameters of the method
      Returns:
      the method named classname.methodname with parameters params
      Throws:
      ClassNotFoundException - if the class is not found
      NoSuchMethodException - if the method is not found

    • setFinalField

      public static void setFinalField(Object o, String fieldName, @Interned Object value) throws NoSuchFieldException
      Sets the given field, which may be final and/or private. Restores the field's original accessibility.
      Parameters:
      o - object in which to set the field; null iff the field is static
      fieldName - name of field to set
      value - new value of field; may be null iff the field is nullable
      Throws:
      NoSuchFieldException - if the field does not exist in the object

    • getPrivateField

      public static @Nullable Object getPrivateField(Object o, String fieldName) throws NoSuchFieldException
      Reads the given field, which may be private. Restores the field's original accessibility.
      Parameters:
      o - object in which to get the field
      fieldName - name of field to get
      Returns:
      value of field
      Throws:
      NoSuchFieldException - if the field does not exist in the object

    • leastUpperBound

      public static <T> @Nullable Class<T> leastUpperBound(@Nullable Class<T> a, @Nullable 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 class
      b - a class
      Returns:
      the least upper bound of the two classes, or null if both are null

    • leastUpperBound

      public static <T> @Nullable Class<T> leastUpperBound(@Nullable 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 - an array of classes
      Returns:
      the least upper bound of all the given classes, or null if the array is empty or all its elements are null

    • leastUpperBound

      public static <T> @Nullable Class<T> leastUpperBound(@PolyMustCall @PolyNull 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 - an array of objects
      Returns:
      the least upper bound of the classes of the given objects, or null if the array is empty or all its elements are null

    • leastUpperBound

      public static <T> @Nullable Class<T> leastUpperBound(List<? extends @Nullable 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 the list is empty or all its elements are null