Remove redundant null checks from Java-to-Kotlin migration (#88)

Author: Copilot

src/main/kotlin/cz/vutbr/fit/interlockSim/context/DefaultContext.kt

@@ -28,8 +28,6 @@ import cz.vutbr.fit.interlockSim.sim.InOutWorker
 import cz.vutbr.fit.interlockSim.sim.LoopProcess
 import cz.vutbr.fit.interlockSim.sim.ShuntingLoop
 import cz.vutbr.fit.interlockSim.exceptions.SimulationException
-import cz.vutbr.fit.interlockSim.exceptions.requireEditor
-import cz.vutbr.fit.interlockSim.exceptions.requireEditorNotNull
 import cz.vutbr.fit.interlockSim.exceptions.requireSimulation
 import cz.vutbr.fit.interlockSim.exceptions.requireSimulationNotNull
 import cz.vutbr.fit.interlockSim.exceptions.requireValidArgument
@@ -245,11 +243,9 @@ abstract class DefaultContext :
 		val nodecell2: NodeCell = Util.assertNodeCell(getGrid().get(key2)!!)
 
 		for (s1: Segment in nodecell1.joins()) {
-			requireEditorNotNull(s1) { "Segment s1 cannot be null for nodecell $nodecell1" }
 			val p1 = s1.transform(key1)
 			if (used(p1)) continue
 			for (s2: Segment in nodecell2.joins()) {
-				requireEditorNotNull(s2) { "Segment s2 cannot be null for nodecell $nodecell2" }
 				if (s1 == s2) continue // stejne segmenty se nepropoji
 				val p2 = s2.transform(key2)
 				if (used(p2)) continue
@@ -284,7 +280,6 @@ abstract class DefaultContext :
 		key2: Point,
 		trackBlock: TrackBlock
 	): Boolean {
-		requireEditor(key1 != null && key2 != null) { "Keys cannot be null in hardJoin" }
 		if (key1.distance(key2) > SQRT2) {
 			val blockEndFrom = s1.transform(key1)
 			val blockEndTo = s2.transform(key2)
@@ -321,7 +316,6 @@ abstract class DefaultContext :
 		key2: Point,
 		trackBlock: TrackBlock
 	): Map<Point, TrackBlockPart>? {
-		if (pi1 == null || pi2 == null) throw IllegalArgumentException()
 		val p1 = pi1
 		val p2 = pi2
 
@@ -359,8 +353,8 @@ abstract class DefaultContext :
 		key2: Point,
 		trackBlock: TrackBlock
 	): MutableMap<Point, TrackBlockPart>? {
-		requireValidArgument(bresenham != null && bresenham.isNotEmpty()) {
-			"Bresenham path list cannot be null or empty"
+		requireValidArgument(bresenham.isNotEmpty()) {
+			"Bresenham path list cannot be empty"
 		}
 		val map: MutableMap<Point, TrackBlockPart> = linkedMapOf()
 		var from = key1
@@ -394,7 +388,6 @@ abstract class DefaultContext :
 		to: Point,
 		block: TrackBlock
 	): TrackBlockPart? {
-		requireEditorNotNull(block) { "TrackBlock cannot be null in createPart" }
 		if (used(middle)) return null
 		if (from == to || from == middle || middle == to) return null
 
@@ -426,9 +419,6 @@ abstract class DefaultContext :
 		p2: Point,
 		points: MutableList<Point>
 	): Boolean {
-		requireValidArgument(key1 != null && key2 != null && p1 != null && p2 != null) {
-			"All points must be non-null in bresenham algorithm"
-		}
 		requireValidArgument(key1 != p1 && key2 != p2 && key1 != p2 && key2 != p1) {
 			"Keys and intermediate points must be distinct in bresenham algorithm"
 		}
@@ -548,7 +538,6 @@ abstract class DefaultContext :
 		key: Point,
 		nodeCell: NodeCell
 	) {
-		requireEditorNotNull(key) { "Cell key cannot be null in putCell" }
 		// Validate coordinates are within grid bounds
 		if (key.x < 0 || key.y < 0 || key.x >= railwayNetGrid.getCols() || key.y >= railwayNetGrid.getRows()) {
 			throw ContextCreationException(
@@ -560,7 +549,6 @@ abstract class DefaultContext :
 
 		// vedlejsi Nody (sousedni bunky)
 		for (s1: Segment in nodeCell.joins()) {
-			requireEditorNotNull(s1) { "Segment s1 cannot be null for nodeCell $nodeCell" }
 			val p = s1.transform(key)
 			// Skip neighbor if it's outside grid bounds (boundary cells)
 			if (p.x < 0 || p.y < 0 || p.x >= railwayNetGrid.getCols() || p.y >= railwayNetGrid.getRows()) {
@@ -619,7 +607,6 @@ abstract class DefaultContext :
 	 * Remove a track line from the railway network
 	 */
 	override fun removeLine(line: TrackBlock) {
-		requireEditorNotNull(line) { "TrackBlock line cannot be null in removeLine" }
 		extendedUnorientedGraph.remove(line)
 		getGrid().keySet().removeAll(linesKeys.remove(line) ?: emptySet())
 		changeSupport.firePropertyChange(
@@ -656,7 +643,6 @@ abstract class DefaultContext :
 	): Segment? {
 		// If track is not null, use it; otherwise use secondEndTrack
 		if (track != null) return getSegment(separator, track)
-		requireValidArgument(separator != null) { "PathSeparator cannot be null" }
 		requireValidArgument(secondEndTrack != null) { "secondEndTrack cannot be null for separator $separator" }
 		requireValidArgument(separator is OrientedPathSeparator) {
 			"PathSeparator must be OrientedPathSeparator, got ${separator.javaClass.simpleName}"
@@ -673,9 +659,6 @@ abstract class DefaultContext :
 		separator: PathSeparator,
 		track: Track
 	): Segment? {
-		if (separator == null || track == null) {
-			throw IllegalArgumentException("separator or track is null")
-		}
 		return if (track is TrackSection) {
 			@Suppress("UNCHECKED_CAST")
 			val section = track as TrackSection
@@ -696,9 +679,6 @@ abstract class DefaultContext :
 		separator: PathSeparator,
 		section: TrackSection
 	): Segment? {
-		if (section == null) {
-			throw IllegalArgumentException("section is null")
-		}
 		val trackBlock = section.getTrackBlock()
 		if (trackBlock.isInnerElement(separator)) {
 			return trackBlock.getJoin(separator, section)
@@ -749,7 +729,6 @@ abstract class DefaultContext :
 		nodeCell: NodeCell,
 		current: TrackBlock?
 	): TrackBlock? {
-		if (nodeCell == null) throw IllegalArgumentException("node is null")
 		val location = getLocation(nodeCell)
 		val segment = getSegment(location, current)
 		val followingSegment = nodeCell.getFollowingSegment(segment)
@@ -766,7 +745,6 @@ abstract class DefaultContext :
 		separator: PathSeparator,
 		current: TrackSection?
 	): TrackSection? {
-		if (separator == null) throw IllegalArgumentException("separator is null")
 		var trackBlock: TrackBlock? = null
 		if (current != null) {
 			trackBlock = current.getTrackBlock()
@@ -862,12 +840,10 @@ abstract class DefaultContext :
 		next: Track?,
 		previous: Track?
 	): Boolean {
-		requireSimulation(separator != null) { "Separator cannot be null in isSeparatorInDirection" }
 		val segment = getSegment(separator, next, previous)
 		if (segment == null && separator is InOut) return true
 		requireSimulation(segment != null) { "Segment cannot be null for separator $separator" }
 		val direction = separator.direction()
-		requireSimulation(direction != null) { "Direction cannot be null for oriented separator" }
 		val inDirection = segment === direction
 		logger.debug {
 			"isSeparatorInDirection: separator $separator, segment=$segment, direction=$direction, result=$inDirection"
@@ -882,9 +858,6 @@ abstract class DefaultContext :
 		sep: PathSeparator,
 		nxt: TrackSection
 	): Path? {
-		if (sep == null || nxt == null) {
-			throw IllegalArgumentException("wrong arguments for aPath finding")
-		}
 		logger.debug { "pathToNextSemaphore: searching path from $sep via track section" }
 		var separator = sep
 		var previous: TrackSection? = null
@@ -940,7 +913,7 @@ abstract class DefaultContext :
 	 * Add report types to be reported
 	 */
 	override fun addReportTypes(vararg types: ReportType) {
-		if (types == null || types.isEmpty()) {
+		if (types.isEmpty()) {
 			allowedReportTypes.clear()
 		} else {
 			allowedReportTypes.addAll(types.asList())
@@ -956,9 +929,8 @@ abstract class DefaultContext :
 	 * Remove report types from reporting
 	 */
 	override fun removeReportTypes(vararg types: ReportType) {
-		if (types == null || types.isEmpty()) return
+		if (types.isEmpty()) return
 		for (t in types) {
-			if (t == null) continue
 			allowedReportTypes.remove(t)
 		}
 	}

src/main/kotlin/cz/vutbr/fit/interlockSim/context/DefaultRailWayNetGrid.kt

@@ -142,7 +142,6 @@ class DefaultRailWayNetGrid(
 	 */
 	@Synchronized
 	fun remove(key: Point) {
-		requireValidState(key != null) { "Key cannot be null" }
 		val removed: Cell? = getCells().remove(key)
 		val remove2: Point? = getReverseTable().remove(removed)
 		requireValidState(key == remove2) {

src/main/kotlin/cz/vutbr/fit/interlockSim/gui/RailwayNetGridCanvas.kt

@@ -14,8 +14,6 @@ import cz.vutbr.fit.interlockSim.context.EditingContext
 import cz.vutbr.fit.interlockSim.context.EditingContextFactory
 import cz.vutbr.fit.interlockSim.context.SimulationContext
 import cz.vutbr.fit.interlockSim.exceptions.requireEditor
-import cz.vutbr.fit.interlockSim.exceptions.requireEditorNotNull
-import cz.vutbr.fit.interlockSim.exceptions.requireValidState
 import cz.vutbr.fit.interlockSim.gui.gridcanvas.CellRenderer
 import cz.vutbr.fit.interlockSim.gui.gridcanvas.EditorCellRenderer
 import cz.vutbr.fit.interlockSim.gui.gridcanvas.GridCanvasEditingPopupMenu
@@ -234,7 +232,6 @@ class RailwayNetGridCanvas :
 
 	// Update context and recalculate display
 	private fun changeContext(cont: Context) {
-		requireEditorNotNull(cont) { "Context cannot be null" }
 		if (context != null) {
 			context!!.removePropertyChangeListener(this)
 		}
@@ -263,7 +260,6 @@ class RailwayNetGridCanvas :
 		for (entry in grid) {
 			val key = entry.key
 			val cell = entry.value
-			requireValidState(key != null && cell != null) { "Grid entry has null key or value: ($key, $cell)" }
 
 			val x = key.x * CELL_WIDTH
 			val y = key.y * CELL_HEIGHT

src/main/kotlin/cz/vutbr/fit/interlockSim/gui/StatusBar.kt

@@ -35,9 +35,7 @@ class StatusBar :
 				val source = e.source
 				requireValidState(source is StatusProducer) { "Source must be a StatusProducer" }
 				val status = (source as StatusProducer).getStatus(e)
-				if (status != null) {
-					text = status
-				}
+				text = status
 			}
 		}
 

src/main/kotlin/cz/vutbr/fit/interlockSim/gui/action/NodeCellAction.kt

@@ -66,9 +66,7 @@ class NodeCellAction(
 			g.color = Color.WHITE
 			g.fillRect(0, 0, iconSize, iconSize)
 			g.color = Color.BLACK
-			if (cell != null) {
-				editorCellRenderer.draw(g, cell)
-			}
+			editorCellRenderer.draw(g, cell)
 			return ImageIcon(img)
 		}
 

src/main/kotlin/cz/vutbr/fit/interlockSim/gui/gridcanvas/CellRenderer.kt

@@ -113,7 +113,6 @@ abstract class CellRenderer(
 		g: Graphics2D,
 		cell: Cell
 	) {
-		requireValidState(cell != null) { "Cell cannot be null" }
 
 		try {
 			// Use reflection to find and invoke the specific draw method for this cell type

src/main/kotlin/cz/vutbr/fit/interlockSim/gui/gridcanvas/GridCanvasPopupMenu.kt

@@ -9,7 +9,6 @@
  */
 package cz.vutbr.fit.interlockSim.gui.gridcanvas
 
-import cz.vutbr.fit.interlockSim.exceptions.requireValidState
 import cz.vutbr.fit.interlockSim.gui.RailwayNetGridCanvas
 import cz.vutbr.fit.interlockSim.objects.cells.Cell
 import cz.vutbr.fit.interlockSim.objects.cells.NodeCell
@@ -57,7 +56,6 @@ abstract class GridCanvasPopupMenu : JPopupMenu() {
 		key: cz.vutbr.fit.interlockSim.util.Point?,
 		cell: Cell?
 	) {
-		requireValidState(canvas != null && e != null) { "Canvas and event cannot be null" }
 		if (key == null || cell == null) return
 		this.canvas = canvas
 		reorganizeMenu(key, cell)

src/main/kotlin/cz/vutbr/fit/interlockSim/objects/cells/Cell.kt

@@ -81,7 +81,6 @@ interface Cell {
 		 * @return neighbour Point
 		 */
 		fun transform(from: Point): Point {
-			requireValidState(from != null) { "Point cannot be null" }
 			val tr = Point(from.x + dx, from.y + dy)
 			requireValidState(from != tr) { "Transformed point must be different from original: segment=$this" }
 			return tr

src/main/kotlin/cz/vutbr/fit/interlockSim/objects/cells/RailSemaphore.kt

@@ -99,7 +99,7 @@ open class RailSemaphore(
 	open fun setSignal(signal: Signal) {
 		logger.debug {
 			if (this.signal != signal) {
-				"Semaphore ${if (getName() != null) getName() else this.hashCode()} " +
+				"Semaphore ${getName()} " +
 					"signal change: ${this.signal} -> $signal at t=${jDisco.Process.time()}"
 			} else {
 				""

src/main/kotlin/cz/vutbr/fit/interlockSim/objects/paths/AbstractPath.kt

@@ -13,7 +13,6 @@ import cz.vutbr.fit.interlockSim.context.SimulationContext
 import cz.vutbr.fit.interlockSim.context.SimulationContext.ReportType
 import cz.vutbr.fit.interlockSim.exceptions.requireSimulation
 import cz.vutbr.fit.interlockSim.exceptions.requireSimulationNotNull
-import cz.vutbr.fit.interlockSim.exceptions.requireValidArgument
 import cz.vutbr.fit.interlockSim.objects.cells.InOut
 import cz.vutbr.fit.interlockSim.objects.cells.RailSemaphore
 import cz.vutbr.fit.interlockSim.objects.cells.RailSwitch
@@ -191,7 +190,6 @@ abstract class AbstractPath protected constructor(
 		previous: Track?,
 		next: Track
 	): Boolean {
-		requireValidArgument(methodName != null && next != null) { "Method name and next track must not be null" }
 		val from = context.getSegment(separator, previous, next)
 		val to = context.getSegment(separator, next, previous)
 		requireSimulation(!conflict(from, to)) { "Segment conflict: from=$from, to=$to" }