8301989: new javax.swing.text.DefaultCaret().setBlinkRate(N) results …

…in NPE

Reviewed-by: dnguyen, honkar, prr

src/java.desktop/share/classes/javax/swing/text/DefaultCaret.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1050,7 +1050,7 @@ public void setBlinkRate(int rate) {
             throw new IllegalArgumentException("Invalid blink rate: " + rate);
         }
         if (rate != 0) {
-            if (component.isEditable()) {
+            if (component != null && component.isEditable()) {
                 if (flasher == null) {
                     flasher = new Timer(rate, handler);
                 }
@@ -1065,7 +1065,7 @@ public void setBlinkRate(int rate) {
                 flasher.removeActionListener(handler);
                 flasher = null;
             }
-            if (component.isEditable() && isBlinkRateSaved) {
+            if ((component == null || component.isEditable()) && isBlinkRateSaved) {
                 savedBlinkRate = 0;
                 isBlinkRateSaved = false;
             }

test/jdk/javax/swing/text/DefaultCaret/SetCaretRateTest.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import javax.swing.text.Caret;
+import javax.swing.text.DefaultCaret;
+
+/*
+ * @test
+ * @bug 8301989
+ * @summary Test checks that there is no exception happens
+ *          when setting blink rate on a javax.swing.DefaultCaret that is not
+ *          associated with any text component
+ * @run main SetCaretRateTest
+ */
+public class SetCaretRateTest {
+    public static void main(String[] args) {
+        Caret caret = new DefaultCaret();
+        caret.setBlinkRate(0);
+        caret.setBlinkRate(100);
+        caret.setBlinkRate(0);
+        caret = new DefaultCaret();
+        caret.setBlinkRate(100);
+        caret.setBlinkRate(0);
+        caret.setBlinkRate(100);
+    }
+}