Created logic for limiting the number of identical error messages that

appears in popups. From now there should be a cooldown of 15 seconds
between exception dialogs opening for identical stacktraces. The cooldown
may need to be tweeked later but I think this is better than before.

src/main/java/io/github/stekeblad/videouploader/utils/AlertUtils.java

@@ -1,5 +1,6 @@
 package io.github.stekeblad.videouploader.utils;
 
+import io.github.stekeblad.videouploader.utils.exceptionHistory.ExceptionHistory;
 import javafx.application.Platform;
 import javafx.geometry.HPos;
 import javafx.geometry.Insets;
@@ -24,6 +25,8 @@
  */
 public class AlertUtils {
 
+    private static ExceptionHistory exceptionHistory = new ExceptionHistory();
+
     /**
      * Creates an Alert, sets Modality, Header, Content and adjusts the minHeight
      * @param header Custom window title
@@ -163,14 +166,16 @@ public static void simpleClose_longContent(String header, String content) {
      */
     public static void exceptionDialog(String header, String content, Throwable exception) {
         String stackTrace = getStacktrace(exception);
-        String fullContent = content +
-                "\nHere is the error details:" +
-                "\n-----------------------------------------" +
-                "\n" + exception.getMessage() +
-                "\n-----------------------------------------" +
-                "\n" + stackTrace;
-        GridPane pane = makeLongMsgPane(fullContent, false);
-        paneToWindow(pane, header);
+        if (!exceptionHistory.isInHistory(stackTrace)) {
+            String fullContent = content +
+                    "\nHere is the error details:" +
+                    "\n-----------------------------------------" +
+                    "\n" + exception.getMessage() +
+                    "\n-----------------------------------------" +
+                    "\n" + stackTrace;
+            GridPane pane = makeLongMsgPane(fullContent, false);
+            paneToWindow(pane, header);
+        }
     }
 
     /**

src/main/java/io/github/stekeblad/videouploader/utils/exceptionHistory/ExceptionHistory.java

@@ -0,0 +1,52 @@
+package io.github.stekeblad.videouploader.utils.exceptionHistory;
+
+import java.time.Duration;
+import java.util.ArrayList;
+
+/**
+ * The ExceptionHistory holds a list of {@link io.github.stekeblad.videouploader.utils.exceptionHistory.ExceptionHistoryPost}
+ * with exceptions that recently have been seen. The purpose is to prevent multiple error dialogs from displaying the
+ * same error message in rapid succession. This can be archived by calling the {@link #isInHistory(String)} method and
+ * checking the return value before showing an exception dialog. If true is returned then an exception with the same
+ * stacktrace was seen less than 15 seconds ago and you may want to skip showing an error message.
+ */
+public class ExceptionHistory {
+    private ArrayList<ExceptionHistoryPost> exceptionHistoryPosts;
+
+    public ExceptionHistory() {
+        exceptionHistoryPosts = new ArrayList<>();
+    }
+
+    /**
+     * Checks if an exception with the same stacktrace as {@code stacktrace} has been seen within the last 15 seconds
+     * and if so returns true, if there is no record of an identical stacktrace then the stacktrace is recorded and
+     * false is returned. If unsure how to get the stacktrace as a string, please look at {@code getStacktrace(Throwable)}
+     * in the class {@link io.github.stekeblad.videouploader.utils.AlertUtils}
+     *
+     * @param stacktrace the stacktrace to compare to previously seen stacktraces
+     * @return true if an identical stacktrace has been seen in the last 15 seconds, false otherwise.
+     */
+    public boolean isInHistory(String stacktrace) {
+        for (int i = 0; i < exceptionHistoryPosts.size(); /* no increment */) {
+            ExceptionHistoryPost post = exceptionHistoryPosts.get(i);
+            // Test the age of the history post.
+            // If it was more than a minute ago since its first appeared its to old and should be removed.
+            // in this case we do not want to increment i because we remove one element and everything after it is shifted
+            // one step towards the beginning on the list.
+            if (post.getTimeSinceAdded().compareTo(Duration.ofSeconds(15)) > 0)
+                exceptionHistoryPosts.remove(i);
+
+                // Check if it exists a stacktrace in the exceptionHistoryPosts with the same stacktrace as the provided one.
+                // If there is a match this exception happened recently, return true.
+            else if (post.getStacktrace().equals(stacktrace))
+                return true;
+
+                // Else progress to the next post
+            else
+                i++;
+        }
+        // The stacktrace is new, add it to the history
+        exceptionHistoryPosts.add(new ExceptionHistoryPost(stacktrace));
+        return false;
+    }
+}

src/main/java/io/github/stekeblad/videouploader/utils/exceptionHistory/ExceptionHistoryPost.java

@@ -0,0 +1,31 @@
+package io.github.stekeblad.videouploader.utils.exceptionHistory;
+
+import java.time.Duration;
+import java.time.Instant;
+
+/**
+ * ExceptionHistoryPost represents one exception that has happened and contains its stacktrace and the
+ * {@link java.time.Instant} the post was created. ExceptionHistoryPost is used by
+ * {@link io.github.stekeblad.videouploader.utils.exceptionHistory.ExceptionHistory} to track exceptions that recently
+ * been caught and prevent multiple error dialogs from displaying the same error message in rapid succession.
+ */
+class ExceptionHistoryPost {
+    private String Stacktrace;
+    private Instant TimeAdded;
+
+    ExceptionHistoryPost(String stacktrace) {
+        Stacktrace = stacktrace;
+        TimeAdded = Instant.now();
+    }
+
+    String getStacktrace() {
+        return Stacktrace;
+    }
+
+    /**
+     * @return the time between the current instant and the instant the ExceptionHistoryPost was created
+     */
+    Duration getTimeSinceAdded() {
+        return Duration.between(TimeAdded, Instant.now());
+    }
+}