public Location getNextLocation$()\{$

if $($currentLocation $==$ null$)\{$

currentLocation $=$ locationsTree.getRoot$()$;

$\}$ else $\{$

currentLocation $=$ getNextInLevelOrder$($locationsTree$.$getRoot$(),$ currentLocation$)$;

$\}$

return currentLocation $!=$ null $?$ currentLocation.getData$()$ : null;

$\}$

public Location getPreviousLocation$()\{$

if $($currentLocation $==$ null$)\{$

currentLocation $=$ locationsTree.getRoot$()$;

$\}$ else $\{$

currentLocation $=$ getPreviousInLevelOrder$($locationsTree$.$getRoot$(),$ currentLocation$)$;

$\}$

return currentLocation $!=$ null $?$ currentLocation.getData$()$ : null;

$\}$

private TNode getNextInLevelOrder$($TNode root, TNode currentNode$)\{$

LinkedQueue$>$ queue $=$ new LinkedQueue$<>()$;

boolean foundCurrent $=$ false;

if $($root $==$ null$)\{$

return null;

$\}$

queue.enqueue$($root$)$;

while $(!$queue.isEmpty$())\{$

TNode node $=$ queue.dequeue$()$;

if $($foundCurrent$)\{$

return node;

$\}$

if $($node $==$ currentNode$)\{$

foundCurrent $=$ true;

$\}$

if $($node$.$getLeft$()!=$ null$)\{$

queue.enqueue$($node$.$getLeft$())$;

$\}$

if $($node$.$getRight$()!=$ null$)\{$

queue.enqueue$($node$.$getRight$())$;

$\}$

$\}$

return null;

$\}$

private TNode getPreviousInLevelOrder$($TNode root, TNode currentNode$)\{$

LinkedQueue$>$ queue $=$ new LinkedQueue$<>()$;

TNode previousNode $=$ null;

if $($root $==$ null$)\{$

return null;

$\}$

queue.enqueue$($root$)$;

while $(!$queue.isEmpty$())\{$

TNode node $=$ queue.dequeue$()$;

if $($node $==$ currentNode$)\{$

return previousNode;

$\}$

previousNode $=$ node;

if $($node$.$getLeft$()!=$ null$)\{$

queue.enqueue$($node$.$getLeft$())$;

$\}$

if $($node$.$getRight$()!=$ null$)\{$

queue.enqueue$($node$.$getRight$())$;

$\}$

$\}$

return null;

$\}$

$\}$ there is a problem in navigation level by level and from left to right here