8364230: javax/swing/text/StringContent can be migrated away from using finalize

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

@@ -27,6 +27,7 @@
 import java.util.Vector;
 import java.io.Serializable;
 import javax.swing.undo.*;
+import java.lang.ref.WeakReference;
 
 /**
  * An implementation of the AbstractDocument.Content interface that is
@@ -227,7 +228,7 @@ synchronized void updateMarksForInsert(int offset, int length) {
         int n = marks.size();
         for (int i = 0; i < n; i++) {
             PosRec mark = marks.elementAt(i);
-            if (mark.unused) {
+            if (mark.get() == null) {
                 // this record is no longer used, get rid of it
                 marks.removeElementAt(i);
                 i -= 1;
@@ -242,7 +243,7 @@ synchronized void updateMarksForRemove(int offset, int length) {
         int n = marks.size();
         for (int i = 0; i < n; i++) {
             PosRec mark = marks.elementAt(i);
-            if (mark.unused) {
+            if (mark.get() == null) {
                 // this record is no longer used, get rid of it
                 marks.removeElementAt(i);
                 i -= 1;
@@ -278,7 +279,7 @@ protected Vector getPositionsInRange(Vector v, int offset,
         Vector placeIn = (v == null) ? new Vector() : v;
         for (int i = 0; i < n; i++) {
             PosRec mark = marks.elementAt(i);
-            if (mark.unused) {
+            if (mark.get() == null) {
                 // this record is no longer used, get rid of it
                 marks.removeElementAt(i);
                 i -= 1;
@@ -303,7 +304,7 @@ protected void updateUndoPositions(Vector positions) {
         for(int counter = positions.size() - 1; counter >= 0; counter--) {
             UndoPosRef ref = (UndoPosRef) positions.elementAt(counter);
             // Check if the Position is still valid.
-            if(ref.rec.unused) {
+            if(ref.rec.get() == null) {
                 positions.removeElementAt(counter);
             }
             else
@@ -323,40 +324,27 @@ protected void updateUndoPositions(Vector positions) {
      * it.... the update table holds only a reference
      * to this grungy thing.
      */
-    static final class PosRec {
+    static final class PosRec extends WeakReference<StickyPosition> {
 
-        PosRec(int offset) {
+        PosRec(int offset, StickyPosition position) {
+            super(position);
             this.offset = offset;
         }
 
         int offset;
-        boolean unused;
     }
 
-    /**
-     * This really wants to be a weak reference but
-     * in 1.1 we don't have a 100% pure solution for
-     * this... so this class tries to hack a solution
-     * to causing the marks to be collected.
-     */
     final class StickyPosition implements Position {
 
         StickyPosition(int offset) {
-            rec = new PosRec(offset);
+            rec = new PosRec(offset, this);
             marks.addElement(rec);
         }
 
         public int getOffset() {
             return rec.offset;
         }
 
-        @SuppressWarnings("removal")
-        protected void finalize() throws Throwable {
-            // schedule the record to be removed later
-            // on another thread.
-            rec.unused = true;
-        }
-
         public String toString() {
             return Integer.toString(getOffset());
         }

test/jdk/javax/swing/text/AbstractDocument/StringContentPositionTest.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2025, 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.BadLocationException;
+import javax.swing.text.Position;
+import javax.swing.text.StringContent;
+
+/*
+ * @test
+ * @summary test that StringContent Position APIs behave as expected.
+ */
+
+public class StringContentPositionTest {
+
+    static final int SIZE = 20;
+    static final String TEXT = "hello";
+    static final int LEN = TEXT.length();
+    static final StringContent SC = new StringContent();
+
+    public static void main(String[] args) throws BadLocationException {
+
+        for (int i = 0; i < 1000; i++) {
+            test();
+            System.gc();
+        }
+    }
+
+    static void test() throws BadLocationException {
+
+        Position[] positions = new Position[SIZE];
+
+        for (int i = 0; i < SIZE; i++) {
+            SC.insertString(0, TEXT);
+            positions[i] = SC.createPosition(LEN);
+        }
+        for (int i = 0; i < SIZE; i++) {
+           int expected = ((SIZE - i) * LEN);
+           if (positions[i].getOffset() != expected) {
+               throw new RuntimeException("insert: Bad offset i=" + i + " off=" + positions[i].getOffset());
+           }
+        }
+        SC.remove(0, SIZE * LEN);
+        for (int i = 0; i < SIZE; i++) {
+            if (positions[i].getOffset() != 0) {
+               throw new RuntimeException("remove: Bad offset i=" + i + " off=" + positions[i].getOffset());
+            }
+        }
+     }
+}