boone.util

Class ClassHelper

java.lang.Object

boone.util.ClassHelper

public final class ClassHelper
extends java.lang.Object

Helper for handling classes.

Since:

Wed 2004-06-16

Author:

August Mayer, Helmut A. Mayer

Field Summary

Fields

Modifier and Type	Field and Description
static char	INNER_CLASS_SEPARATOR_CHAR
static char	JAR_PATH_SEPARATOR_CHAR
static java.lang.String	JAR_PATH_SEPARATOR_STRING
static char	PACKAGE_SEPARATOR_CHAR

Constructor Summary

Constructors

Constructor and Description
ClassHelper()

Method Summary

Modifier and Type	Method and Description
static boolean	containsClassName(java.lang.String path, java.lang.String name, char pathSeparatorChar) Checks if the given name is the name of a class in path.
static java.lang.Class	createClassByName(java.lang.String cl) Returns a class by its name inclusively the primitive types and arrays of primitive types, e.g., int[].
static java.lang.String	getBasicName(java.lang.Class c) Extract the basic class name from a Class object.
static java.util.List<java.lang.String>	getClassPath() Returns the class path.
static java.lang.Object	getField(java.lang.Object obj, java.lang.String name) Use Java Reflection to get the value of the object attribute for this Parameter.
static java.lang.Object	getField(java.lang.Object obj, java.lang.String name, java.lang.Object defaultValue) Use Java Reflection to get the value of the object attribute for this Parameter.
static java.lang.String	getNameFromClassPath(java.lang.String name) Returns a path containing 'name' in the resources of the class path.
static java.lang.String	getNameFromDir(java.io.File file, java.lang.String name) Returns the path to a file name containing 'name' starting recursively at directory 'file'.
static java.lang.String	getNameFromFileSystem(java.lang.String path, java.lang.String name) Returns a path containing 'name', where the search starts at 'path'.
static java.lang.String	getNameFromJar(java.io.File file, java.lang.String name) Returns a jar file entry containing a resource with 'name'.
static java.lang.String	getQualifiedName(java.lang.String name) Returns the qualified name of a possibly unqualified class name.
static java.lang.Object	instantiateByClassName(java.lang.String className) Instantiates an Object by passing the name of the Class in a String.
static java.lang.Object	instantiateByClassName(java.lang.String className, java.lang.String[] constructorClassNames, java.lang.Object[] constructorParameters) Instantiates an Object by passing the name of the Class in a String.
static boolean	setField(java.lang.Object obj, java.lang.String name, java.lang.Object value) Set the value of this parameter.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

JAR_PATH_SEPARATOR_CHAR

public static final char JAR_PATH_SEPARATOR_CHAR

See Also:

Constant Field Values

JAR_PATH_SEPARATOR_STRING

public static final java.lang.String JAR_PATH_SEPARATOR_STRING

See Also:

Constant Field Values

PACKAGE_SEPARATOR_CHAR

public static final char PACKAGE_SEPARATOR_CHAR

See Also:

Constant Field Values

INNER_CLASS_SEPARATOR_CHAR

public static final char INNER_CLASS_SEPARATOR_CHAR

See Also:

Constant Field Values

Constructor Detail

ClassHelper

public ClassHelper()

Method Detail

instantiateByClassName

public static java.lang.Object instantiateByClassName(java.lang.String className)

Instantiates an Object by passing the name of the Class in a String. Only the no-arg constructor is used. If you want to use any other

Parameters:

className - the name of the Class to instantiate

Returns:

a new Object (null, if problems occurred)

See Also:

instantiateByClassName(String, String[], Object[])

instantiateByClassName

public static java.lang.Object instantiateByClassName(java.lang.String className,
                                                      java.lang.String[] constructorClassNames,
                                                      java.lang.Object[] constructorParameters)

Instantiates an Object by passing the name of the Class in a String. The 'constructorClassNames' must contain the names of the Classes passed to the desired constructor of the Object. If the profile is null, the no-arg constructor is used. The parameters passed to the constructor must be in 'constructorParameters'.

Parameters:

className - the name of the Class to instantiate

constructorClassNames - the names of the Classes of the parameters (may be null)

constructorParameters - the actual parameters to the constructor (may be null)

Returns:

a new Object (null, if problems occurred)

getBasicName

public static java.lang.String getBasicName(java.lang.Class c)

Extract the basic class name from a Class object. This is the simple name of a class, without package or outer class names.

getQualifiedName

public static java.lang.String getQualifiedName(java.lang.String name)

Returns the qualified name of a possibly unqualified class name.

Parameters:

name - an un/qualified name

Returns:

the qualified name

getClassPath

public static java.util.List<java.lang.String> getClassPath()

Returns the class path. This class path also contains the potential class paths given in manifest files of JAR files. A Java application may be called via '-jar', which makes the standard class path only the given JAR file. However, in the manifest of the JAR file more class paths may be given, which are added to the class path here. Note that now we are not adding paths recursively (as in the manifest class path another JAR file could be given) (maybe, needed in the future).

Returns:

a list of paths

getNameFromClassPath

public static java.lang.String getNameFromClassPath(java.lang.String name)

Returns a path containing 'name' in the resources of the class path. Note, that the string 'name' refers to a resource name (e.g., "Test.class"). Also, if 'name' occurs multiple times only the first occurrence is returned. Paths containing an exclusion string defined in Boone are not searched.

Parameters:

name - a string

Returns:

a path containing 'name', null if not found

getNameFromFileSystem

public static java.lang.String getNameFromFileSystem(java.lang.String path,
                                                     java.lang.String name)

Returns a path containing 'name', where the search starts at 'path'. If the path is a directory, it is recursively searched for a sub-path containing 'name'. Only the sub-path is returned, if 'name' is found anywhere. If the path is a JAR file, then the JAR file is searched for an entry containing 'name'. The 'name' is the name of a resource,

Parameters:

path - path to a directory or a jar file

name - a string

Returns:

sub-path to the file containing 'name', null if not found

getNameFromJar

public static java.lang.String getNameFromJar(java.io.File file,
                                              java.lang.String name)

Returns a jar file entry containing a resource with 'name'.

Parameters:

file - a jar file

name - the resource name to be found in a jar entry

Returns:

the jar entry containing the resource 'name', null if not found

getNameFromDir

public static java.lang.String getNameFromDir(java.io.File file,
                                              java.lang.String name)

Returns the path to a file name containing 'name' starting recursively at directory 'file'.

Parameters:

file - a directory

name - a string to be found

Returns:

a path to a file name containing 'name', null, if not found

containsClassName

public static boolean containsClassName(java.lang.String path,
                                        java.lang.String name,
                                        char pathSeparatorChar)

Checks if the given name is the name of a class in path. Before the name there must be either a file separator or an inner class separator to be deemed a class name. This is checked to avoid the following situation: searching for "Test.class", in the path there is a "MyTest.class", a simple check would return true, though there is no class named "Test.class".

Parameters:

path - a path

name - a class name

pathSeparatorChar - this char depends not only on the system, but also on the resource (e.g., JAR)

Returns:

true, if class name in path

createClassByName

public static java.lang.Class createClassByName(java.lang.String cl)
                                         throws java.lang.ClassNotFoundException

Returns a class by its name inclusively the primitive types and arrays of primitive types, e.g., int[].

Parameters:

cl - The name of the class / type.

Returns:

The class of the class / type.

Throws:

java.lang.ClassNotFoundException

getField

public static java.lang.Object getField(java.lang.Object obj,
                                        java.lang.String name)

Use Java Reflection to get the value of the object attribute for this Parameter. First tries to read the attribute value with getXY, then with isXY, then tries direct access, then gives up.

Parameters:

obj - Object whose attribute value to retrieve.

name - Name of the attribute to retrieve.

Returns:

Attribute value, maybe wrapped in a wrapper object (Integer, Boolean, ...)

Throws:

java.lang.RuntimeException - if it didn't work.

getField

public static java.lang.Object getField(java.lang.Object obj,
                                        java.lang.String name,
                                        java.lang.Object defaultValue)

Use Java Reflection to get the value of the object attribute for this Parameter. First tries to read the attribute value with getXY, then with isXY, then tries direct access, then gives up and returns the default value.

Calls getField(Object, String).

Parameters:

obj - Object whose attribute value to retrieve.

name - Name of the attribute to retrieve.

defaultValue - Default value to return in case of an error.

Returns:

Attribute value, maybe wrapped in a wrapper object (Integer, Boolean, ...)

setField

public static boolean setField(java.lang.Object obj,
                               java.lang.String name,
                               java.lang.Object value)

Set the value of this parameter. The value can either be a suitable Java wrapper object, or a String containing the value of a simple data type.

Parameters:

obj - Object whose attribute value to set.

name - Name of the attribute to retrieve.

value - Value to set the attribute to; can bei either an object, a wrapper for simple data types, or the value of a simple data type.

Returns:

True if it worked, false else.