Fix serial monitor timestamp print regression

Fix #8055

Author: cmaglie

app/src/processing/app/AbstractTextMonitor.java

@@ -174,40 +174,46 @@ public void onSerialRateChange(ActionListener listener) {
     serialRates.addActionListener(listener);
   }
 
-  public void message(final String s) {
-    SwingUtilities.invokeLater(new Runnable() {
-      // Pre-allocate all objects used for streaming data
-      Date t = new Date();
-      String now;
-      StringBuilder out = new StringBuilder(16384);
-      boolean isStartingLine = false;
-
-      public void run() {
-        if (addTimeStampBox.isSelected()) {
-          t.setTime(System.currentTimeMillis());
-          now = logDateFormat.format(t);
-          out.setLength(0);
-
-          StringTokenizer tokenizer = new StringTokenizer(s, "\n", true);
-          while (tokenizer.hasMoreTokens()) {
-            if (isStartingLine) {
-              out.append(now);
-            }
-            String token = tokenizer.nextToken();
-            out.append(token);
-            // tokenizer returns "\n" as a single token
-            isStartingLine = token.charAt(0) == '\n';
+  class AppendMessageAction implements Runnable {
+    public String msg;
+
+    @Override
+    public void run() {
+      if (addTimeStampBox.isSelected()) {
+        t.setTime(System.currentTimeMillis());
+        String now = logDateFormat.format(t);
+        out.setLength(0);
+
+        StringTokenizer tokenizer = new StringTokenizer(msg, "\n", true);
+        while (tokenizer.hasMoreTokens()) {
+          if (isStartingLine) {
+            out.append(now);
           }
-
-          textArea.append(out.toString());
-        } else {
-          textArea.append(s);
+          String token = tokenizer.nextToken();
+          out.append(token);
+          // tokenizer returns "\n" as a single token
+          isStartingLine = token.charAt(0) == '\n';
         }
 
-        if (autoscrollBox.isSelected()) {
-          textArea.setCaretPosition(textArea.getDocument().getLength());
-        }
+        textArea.append(out.toString());
+      } else {
+        textArea.append(msg);
       }
-    });
+
+      if (autoscrollBox.isSelected()) {
+        textArea.setCaretPosition(textArea.getDocument().getLength());
+      }
+    }
+  };
+
+  // Pre-allocate all objects used for streaming data
+  private Date t = new Date();
+  private StringBuilder out = new StringBuilder(16384);
+  private boolean isStartingLine = true;
+  private AppendMessageAction appendMessageAction = new AppendMessageAction();
+
+  public void message(String s) {
+    appendMessageAction.msg = s;
+    SwingUtilities.invokeLater(appendMessageAction);
   }
 }