Fix methods with void return type showing null as return value. Add m…

…ore TODO notes.

src/main/java/ee/ut/dendroloj/SimpleTreeLayout.java

@@ -36,6 +36,9 @@ public static void init(Graph graph, JSlider stepSlider) {
     }
 
     public static void addStepAndUpdateGraph() {
+        // This method causes massive performance issues and extremely high memory usage for relatively small graphs.
+        // TODO: Investigate why and fix it. (Running Katsed.juhuslikHargnemine(8) with Dendrologist enabled provides a reproduction of the issue.)
+
         boolean isLatestStepActive = activeStep == steps.size() - 1;
         if (isLatestStepActive) {
             activeStep += 1;
@@ -92,6 +95,8 @@ private static NodeMetaWrapper wrap(CallTreeNode node) {
 
     private static void updateGraph(NodeMetaWrapper meta, boolean hideNewElements, List<Element> newElements,
                                     double x, double y, double layerHeight, CallTreeNode parent) {
+        // TODO: Fix issues with laying out multiple call graphs at the same time.
+
         // Currently mutable arguments and returns values show the value they had when they were first added to the graph.
         // TODO: Show old values of mutable values when scrolling through history?
 

src/main/java/ee/ut/dendroloj/TreeNode.java

@@ -54,7 +54,8 @@ public String argumentString() {
     }
 
     public String returnValueString() {
-        return valuesToString(new Object[]{returnValue});
+        // TODO: Is there a way to distinguish a null return value from returning nothing (return type void).
+        return returnValue == null ? "" : valuesToString(new Object[]{returnValue});
     }
 
     private static String valuesToString(Object[] values) {

src/test/java/Katsed.java

@@ -49,6 +49,8 @@ static void juhuslikHargnemine(int n) {
     public static void main(String[] args) {
         Dendrologist.wakeUp(1.0, true);
 
+        // juhuslikHargnemine(8);
+        // fib(8);
         pööraJupid(new int[]{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11});
     }
 }