org.mmbase.util

Class NodeComparator

java.lang.Object

org.mmbase.util.NodeComparator

All Implemented Interfaces:

Comparator<MMObjectNode>

public class NodeComparator
extends Object
implements Comparator<MMObjectNode>

This class implements the Comparator interface for comparing MMObjectNodes. At forehand you specify in which fields a specified nodes should be compared, these fields may not have a null value.

Version:

$Id$

Author:

Pierre van Rooden

Application:

Tools

Field Summary

Fields

Modifier and Type	Field and Description
static String	DOWN
static String	UP

Constructor Summary

Constructors

Constructor and Description
NodeComparator(List<String> fields) Simple constructor that uses the default sort order (UP).
NodeComparator(List<String> fields, List<String> sortDirs) Constructor in which you specify the sort order (UP or DOWN) per field.

Method Summary

Modifier and Type	Method and Description
int	compare(MMObjectNode o1, MMObjectNode o2) The two message nodes will be compared using the compare function of the values of their fields.
boolean	equals(Object obj) Returns whether another object is equal to this comparator (that is, compare the same fields in the same order).
int	hashCode() Returns the comparator's hash code.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

comparing, comparing, comparingDouble, comparingInt, comparingLong, naturalOrder, nullsFirst, nullsLast, reversed, reverseOrder, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Field Detail

UP

public static final String UP

See Also:

Constant Field Values

DOWN

public static final String DOWN

See Also:

Constant Field Values

Constructor Detail

NodeComparator

public NodeComparator(List<String> fields)

Simple constructor that uses the default sort order (UP).

Parameters:

fields - the fields on which the message nodes get compared.

NodeComparator

public NodeComparator(List<String> fields,
                      List<String> sortDirs)

Constructor in which you specify the sort order (UP or DOWN) per field.

Parameters:

fields - the fields on which the message nodes get compared.

sortDirs - the sort directions (UP or DOWN) for each field.

Method Detail

compare

public int compare(MMObjectNode o1,
                   MMObjectNode o2)

The two message nodes will be compared using the compare function of the values of their fields. Only Comparable values can be used (String, Numbers, Date), as well as Boolean values. In other cases it's assumed that the values cannot be ordered.
Note: this class assumes that values in fields are of similar types (comparable to each other).

Specified by:

compare in interface Comparator<MMObjectNode>

Parameters:

o1 - the first object to compare

o2 - the second object to compare

Returns:

0 if both objects are equal, -1 if object 1 is 'less than' object 2, and +1 if object 1 is 'greater than' object 2.

equals

public boolean equals(Object obj)

Returns whether another object is equal to this comparator (that is, compare the same fields in the same order).

Specified by:

equals in interface Comparator<MMObjectNode>

Overrides:

equals in class Object

Parameters:

obj - the object to compare

Returns:

true if the objects are equal

Throws:

ClassCastException

hashCode

public int hashCode()

Returns the comparator's hash code.

Overrides:

hashCode in class Object

See Also:

Object.hashCode()