uk.ac.starlink.table.join
Class RowLink

java.lang.Object
  uk.ac.starlink.table.join.RowLink

All Implemented Interfaces:

java.lang.Comparable

Direct Known Subclasses:

PairsRowLink, RowLink2

public class RowLink
extends java.lang.Object
implements java.lang.Comparable

Represents an ordered set of RowRefs which are considered in some way linked to each other. Although it doesn't implement the SortedSet interface (being immutable this wouldn't gain you much) its spirit is that of a sorted set - its equals and hashCode methods are implemented such that two RowLinks which contain equivalent groups of RowRef objects are considered the same. This makes RowLink instances suitable for use as keys in hashes that should not contain duplicate entries for duplicate links. The getRef method returns RowRefs in their natural order.

Constructor Summary

RowLink(java.util.Collection rows)
Constructs a new RowLink from a Collection of RowRef objects.

RowLink(RowRef row)
Convenience constructor to construct a singleton RowLink.

RowLink(RowRef[] rows)
Constructs a new RowLink from an array of RowRef objects.

Method Summary

int	compareTo(java.lang.Object o) Comparison order compares first table (if present in both objects) first, etc.
boolean	equals(java.lang.Object o) Assesses equality.
RowRef	getRef(int i) Returns the ith row ref in this link.
int	hashCode() Returns a hash code which is consistent with the equals method.
int	size() Returns the number of rows linked by this object.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

RowLink

public RowLink(java.util.Collection rows)

Constructs a new RowLink from a Collection of RowRef objects. An unchecked exception will be thrown if rows contains some elements which are not instances of RowRef.

Parameters:

rows - collection of RowRef objects

RowLink

public RowLink(RowRef[] rows)

Constructs a new RowLink from an array of RowRef objects.

Parameters:

rows - array of row references

RowLink

public RowLink(RowRef row)

Convenience constructor to construct a singleton RowLink.

Parameters:

row - sole row

Method Detail

size

public int size()

Returns the number of rows linked by this object.

Returns:

number of RowRefs

getRef

public RowRef getRef(int i)

Returns the i^th row ref in this link.

Parameters:

i - index

Returns:

RowRef at i

equals

public boolean equals(java.lang.Object o)

Assesses equality. Two RowLink objects are equal if they contain equivalent sets of RowRefs.

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Returns a hash code which is consistent with the equals method. Since RowLinks are immutable, this is only calculated once, for efficiency.

Overrides:

hashCode in class java.lang.Object

compareTo

public int compareTo(java.lang.Object o)

Comparison order compares first table (if present in both objects) first, etc.

Specified by:

compareTo in interface java.lang.Comparable

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object