com.antelmann.util
Class MethodComparator<T>

java.lang.Object
  com.antelmann.util.MethodComparator<T>

All Implemented Interfaces:

Comparator<T>

public class MethodComparator<T>
extends Object
implements Comparator<T>

compares objects by the return value of a specified method name. This Comparator uses reflection to access the return values of the methods to be compared. If the return value in used is not Comparable, a UniversalComparator is used to handle the comparison.

Author:

Holger Antelmann

Constructor Summary

MethodComparator(String methodName)
calls MethodComparator(methodName, true)

MethodComparator(String methodName, boolean ascending)
the methodName (usually a 'getter'-method) must have no arguments for the objects to be compared.

Method Summary

int	compare(T o1, T o2) if the object returned by the specified method of the first given object doesn't implement Comparable, the toString() value of that object is used instead.
String	getMethodName()
UniversalComparator	getUniversalComparator() returns the embedded UniversalComparator in use for customization
static String[]	getUsableMethodNames(Class<?> c, boolean comparableReturnValuesOnly) lists all method names of the given class that take no parameters and return something but void - and are therefore usable for a MethodComparator.
boolean	isAscending()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals

Constructor Detail

MethodComparator

public MethodComparator(String methodName)

calls MethodComparator(methodName, true)

MethodComparator

public MethodComparator(String methodName,
                        boolean ascending)

the methodName (usually a 'getter'-method) must have no arguments for the objects to be compared. If ascending is false, the return value of compareTo(Object) will be reversed.

Method Detail

getUniversalComparator

public UniversalComparator getUniversalComparator()

returns the embedded UniversalComparator in use for customization

getUsableMethodNames

public static String[] getUsableMethodNames(Class<?> c,
                                            boolean comparableReturnValuesOnly)

lists all method names of the given class that take no parameters and return something but void - and are therefore usable for a MethodComparator. If comparableReturnValuesOnly is true, the return values of the methods must also implement Comparable.

getMethodName

public String getMethodName()

isAscending

public boolean isAscending()

compare

public int compare(T o1,
                   T o2)
            throws ClassCastException

if the object returned by the specified method of the first given object doesn't implement Comparable, the toString() value of that object is used instead. If a null value is encountered, it is considered to come before any other value.

Specified by:

compare in interface Comparator<T>

Throws:

ClassCastException - if any of the following Exceptions occur: InvocationTargetException, NoSuchMethodException, NoSuchMethodException