org.apache.openjpa.lib.util
Class JavaVersions

java.lang.Object
  org.apache.openjpa.lib.util.JavaVersions

public class JavaVersions
extends Object

Utilities for dealing with different Java spec versions.

Author:

Abe White

Field Summary

static int

VERSION Java version; one of 2, 3, 4, 5, 6, or 7.

Constructor Summary

JavaVersions()

Method Summary

static Throwable	getCause(Throwable ex) Return the cause of the given throwable.
static Class[]	getParameterizedTypes(Field f) Collects the parameterized type declarations for a given field.
static Class[]	getParameterizedTypes(Method meth) Collects the parameterized return type declarations for a given method.
static Class	getVersionSpecificClass(Class base) Returns a version-specific instance of the specified class
static Class	getVersionSpecificClass(String base) Obtains a subclass of the specific base class that is specific to the current version of Java in use.
static Throwable	initCause(Throwable ex, Throwable cause) Set the cause of the given throwable.
static boolean	isAnnotation(Class cls) Return true if the given type is an annotation.
static boolean	isEnumeration(Class cls) Return true if the given type is an enumeration.
static void	main(String[] args)
static boolean	transferStackTrace(Throwable from, Throwable to) Transfer the stack from one throwable to another, or return false if it cannot be done, possibly due to an unsupported Java version.

Methods inherited from class java.lang.Object

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

Field Detail

VERSION

public static final int VERSION

Java version; one of 2, 3, 4, 5, 6, or 7.

Constructor Detail

JavaVersions

public JavaVersions()

Method Detail

getVersionSpecificClass

public static Class getVersionSpecificClass(Class base)

Returns a version-specific instance of the specified class

Parameters:

base - the base class to check

Returns:

the JDK-version-specific version of the class

See Also:

getVersionSpecificClass(String)

getVersionSpecificClass

public static Class getVersionSpecificClass(String base)
                                     throws ClassNotFoundException

Obtains a subclass of the specific base class that is specific to the current version of Java in use. The heuristic for the class name to load will be that OpenJPA first checks for the name of the class with the current setting of the VERSION field, then each number in decreasing order, until ending in the unqualified name. For example, if we are using JDK 1.5.1, and we want to load "org.apache.openjpa.lib.SomeClass", we will try to load the following classes in order and return the first one that is successfully found and loaded:

1. org.apache.openjpa.lib.SomeClass5
2. org.apache.openjpa.lib.SomeClass4
3. org.apache.openjpa.lib.SomeClass3
4. org.apache.openjpa.lib.SomeClass2
5. org.apache.openjpa.lib.SomeClass1
6. org.apache.openjpa.lib.SomeClass

Parameters:

base - the base name of the class to load

Returns:

the subclass appropriate for the current Java version

Throws:

ClassNotFoundException

isAnnotation

public static boolean isAnnotation(Class cls)

Return true if the given type is an annotation.

isEnumeration

public static boolean isEnumeration(Class cls)

Return true if the given type is an enumeration.

getParameterizedTypes

public static Class[] getParameterizedTypes(Field f)

Collects the parameterized type declarations for a given field.

getParameterizedTypes

public static Class[] getParameterizedTypes(Method meth)

Collects the parameterized return type declarations for a given method.

transferStackTrace

public static boolean transferStackTrace(Throwable from,
                                         Throwable to)

Transfer the stack from one throwable to another, or return false if it cannot be done, possibly due to an unsupported Java version.

getCause

public static Throwable getCause(Throwable ex)

Return the cause of the given throwable.

initCause

public static Throwable initCause(Throwable ex,
                                  Throwable cause)

Set the cause of the given throwable.

main

public static void main(String[] args)