com.intersystems.jdbc

Class IRISIterator

java.lang.Object

com.intersystems.jdbc.IRISIterator

All Implemented Interfaces:

Iterator

public class IRISIterator
extends Object
implements Iterator

IRISIterator allows iterating over the global in the $ORDER sense. In addition to standard methods hasNext and next, this class also provides means of iterating backwards (hasPrevious and previous), as well as retrieving the subscript as well as the node values. The global reference (globalName + subscripts) with which this class is instantiated specifies the root global node. An instance of this class will iterate over the immediate children of the root node. For example, for the following global: ^gbl(1)="a" ^gbl(1,11)="b" ^gbl(1,12)="c" ^gbl(2)="d" Calling IRIS.getIRISIterator("^gbl") will return an iterator that traverses the immediate children of ^gbl, that is, ^gbl(1) and ^gbl(2). Calling IRIS.getIRISIterator("^gbl",1) will return an iterator that traverses the immediate children of ^gbl(1), that is, ^gbl(1,11) and ^gbl(1,12).

Method Summary

Modifier and Type	Method and Description
String	getSubscriptValue() Returns the value of the current subscript.
Object	getValue() Returns the current value.
boolean	hasNext() Returns true if the iteration has more elements.
boolean	hasPrevious() Returns true if the iteration has a previous element.
String	next() Returns the next element in the iteration.
String	previous() Returns the previous element in the iteration.
void	remove() Removes from the underlying collection the last element returned by this iterator.
void	startFrom(Object subscript) Sets the iterator's starting position to the specified subscript.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Iterator

forEachRemaining

Method Detail

startFrom

public void startFrom(Object subscript)

Sets the iterator's starting position to the specified subscript. After calling this method, use next() or previous() to advance the iterator to the next defined sub-node in alphabetic collating sequence. Note that calling getSubscriptValue() or getValue() before the iterator is advanced at least one position will result in an IllegalStateException, since the iterator is not positioned at a defined sub-node. For example, for the following global and iterator: ^gbl("a")=11 ^gbl("b")=22 ^gbl("e")=55 IRISIterator itr = iris.getIRISIterator("^gbl"); The starting position may be a valid sub-node, in which case the next sub-node will be the next valid one. itr.startFrom("a"); while(itr.hasNext()) { itr.next(); System.out.println("subscript="+itr.getSubscriptValue()+", value="+itr.getValue()); } // prints: subscript=b, value=11; subscript=e, value=55 The starting position may also be an invalid sub-node, in which case the next sub-node will be the first valid one in alphabetic collating sequence after the given subscript. itr.startFrom("c"); while(itr.hasNext()) { itr.next(); System.out.println("subscript="+itr.getSubscriptValue()+", value="+itr.getValue()); } // prints: subscript=e, value=55 Calling this method with null as the argument is the same as using the default starting position, which is just before the first sub-node.

Parameters:

subscript - subscript to start from

hasNext

public boolean hasNext()

Returns true if the iteration has more elements. (In other words, returns true if next() would return an element rather than throwing an exception.)

Specified by:

hasNext in interface Iterator

Returns:

true if the iteration has more elements

next

public String next()
            throws NoSuchElementException

Returns the next element in the iteration.

Specified by:

next in interface Iterator

Returns:

the next element in the iteration

Throws:

NoSuchElementException - if the iteration has no more elements

remove

public void remove()
            throws IllegalStateException

Removes from the underlying collection the last element returned by this iterator. This method can be called only once per call to next() or previous().

Specified by:

remove in interface Iterator

Throws:

IllegalStateException - if remove() has been called on the current node with this iterator, or there is no last element returned by this iterator (i.e. no successful next() or previous() calls).

getSubscriptValue

public String getSubscriptValue()
                         throws IllegalStateException

Returns the value of the current subscript.

Returns:

the current subscript value.

Throws:

IllegalStateException - if remove() has been called on the current node with this iterator, or there is no last element returned by this iterator (i.e. no successful next() or previous() calls).

getValue

public Object getValue()
                throws IllegalStateException

Returns the current value.

Returns:

the current value.

Throws:

IllegalStateException - if remove() has been called on the current node with this iterator, or there is no last element returned by this iterator (i.e. no successful next() or previous() calls).

hasPrevious

public boolean hasPrevious()

Returns true if the iteration has a previous element. (In other words, returns true if previous() would return an element rather than throwing an exception.)

Returns:

true if the iteration has a previous element

previous

public String previous()
                throws NoSuchElementException

Returns the previous element in the iteration.

Returns:

the previous element in the iteration

Throws:

NoSuchElementException - if the iteration does not have a previous element