Replace BackgroundTask with SwingWorker

Since "move to Java 6" happened a while ago.

Author: Eswcvlad

src/main/java/com/itextpdf/rups/controller/RupsInstanceController.java

@@ -331,7 +331,7 @@ private void startObjectLoader() {
         loader = new ObjectLoader(
                 this, pdfFile, pdfFile.getOriginalFile().getName(), dialog
         );
-        loader.start();
+        loader.execute();
     }
 
     // tree selection

src/main/java/com/itextpdf/rups/model/BackgroundTask.java

@@ -45,11 +45,12 @@ This file is part of the iText (R) project.
 import com.itextpdf.rups.view.Language;
 
 import javax.swing.SwingUtilities;
+import javax.swing.SwingWorker;
 
 /**
  * Loads the necessary iText PDF objects in Background.
  */
-public class ObjectLoader extends BackgroundTask {
+public class ObjectLoader extends SwingWorker<Void, Void> {
     /**
      * This is the object that wait for task to complete.
      */
@@ -125,11 +126,8 @@ public String getLoaderName() {
         return loaderName;
     }
 
-    /**
-     * @see BackgroundTask#doTask()
-     */
     @Override
-    public void doTask() {
+    protected Void doInBackground() {
         objects = new IndirectObjectFactory(file.getPdfDocument());
         final int n = objects.getXRefMaximum();
         SwingUtilities.invokeLater(() -> {
@@ -142,10 +140,11 @@ public void doTask() {
         SwingUtilities.invokeLater(() -> progress.setTotal(0));
         nodes = new TreeNodeFactory(objects);
         SwingUtilities.invokeLater(() -> progress.setMessage(Language.GUI_UPDATING.getString()));
+        return null;
     }
 
     @Override
-    public void finished() {
+    protected void done() {
         try {
             eventListener.handleOpenDocument(this);
         } catch (Exception ex) {

src/main/java/com/itextpdf/rups/model/ObjectLoader.java

@@ -1,6 +1,6 @@
 /*
     This file is part of the iText (R) project.
-    Copyright (c) 1998-2024 Apryse Group NV
+    Copyright (c) 1998-2025 Apryse Group NV
     Authors: Apryse Software.
 
     This program is free software; you can redistribute it and/or modify
@@ -42,24 +42,34 @@ This file is part of the iText (R) project.
  */
 package com.itextpdf.rups.mock;
 
-import com.itextpdf.rups.model.BackgroundTask;
+import com.itextpdf.rups.model.IProgressDialog;
 
-public class MockedBackgroundTask extends BackgroundTask {
-
-    private boolean taskExecuted;
+/**
+ * {@link IProgressDialog} implementation, that does nothing.
+ */
+public final class NoopProgressDialog implements IProgressDialog {
+    @Override
+    public void setMessage(String msg) {
+        // noop
+    }
 
-    public MockedBackgroundTask() {
-        this.taskExecuted = false;
+    @Override
+    public void setValue(int value) {
+        // noop
     }
 
-    @Override public void doTask() {
-        taskExecuted = true;
+    @Override
+    public void setTotal(int n) {
+        // noop
     }
 
-    @Override public void finished() {
+    @Override
+    public void showErrorDialog(Exception ex) {
+        // noop
     }
 
-    public boolean hasTaskExecuted() {
-        return taskExecuted;
+    @Override
+    public void setVisible(boolean visible) {
+        // noop
     }
 }

src/test/java/com/itextpdf/rups/mock/MockedBackgroundTask.java renamed to src/test/java/com/itextpdf/rups/mock/NoopProgressDialog.java

@@ -43,7 +43,8 @@ This file is part of the iText (R) project.
 package com.itextpdf.rups.view.itext;
 
 import com.itextpdf.rups.controller.PdfReaderController;
-import com.itextpdf.rups.model.IProgressDialog;
+import com.itextpdf.rups.mock.NoopProgressDialog;
+import com.itextpdf.rups.model.IRupsEventListener;
 import com.itextpdf.rups.model.ObjectLoader;
 import com.itextpdf.rups.model.PdfFile;
 import com.itextpdf.rups.view.itext.treenodes.StructureTreeNode;
@@ -52,6 +53,7 @@ This file is part of the iText (R) project.
 import java.io.File;
 import java.io.IOException;
 
+import java.util.concurrent.ExecutionException;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Tag;
 import org.junit.jupiter.api.Test;
@@ -64,7 +66,8 @@ class StructureTreeTest extends ExtendedITextTest {
     private static final String sourceFolder = "./src/test/resources/com/itextpdf/rups/controller/";
 
     @Test
-    void extractMcidContentInStructureTreeTest() throws IOException {
+    void extractMcidContentInStructureTreeTest()
+            throws IOException, ExecutionException, InterruptedException {
         final PdfFile pdfFile = PdfFile.open(
                 new File(sourceFolder + "hello_world_tagged.pdf")
         );
@@ -77,7 +80,8 @@ void extractMcidContentInStructureTreeTest() throws IOException {
     }
 
     @Test
-    void extractMcidContentInStructureTreeWithActualTextTest() throws IOException {
+    void extractMcidContentInStructureTreeWithActualTextTest()
+            throws IOException, ExecutionException, InterruptedException {
         final PdfFile pdfFile = PdfFile.open(
                 new File(sourceFolder + "hello_world_tagged_actualtext.pdf")
         );
@@ -89,14 +93,17 @@ void extractMcidContentInStructureTreeWithActualTextTest() throws IOException {
         Assertions.assertEquals("0 [Olleh ]", nodeLabel);
     }
 
-    private static StructureTreeNode getStructureTreeRootNode(PdfFile pdfFile) {
+    private static StructureTreeNode getStructureTreeRootNode(PdfFile pdfFile)
+            throws ExecutionException, InterruptedException {
 
         PdfReaderController controller = new PdfReaderController(null, null);
+        // Using a noop listener here to prevent threading issues
         ObjectLoader loader = new ObjectLoader(
-                controller, pdfFile, "Test loader", new DummyProgressDialog()
+                new IRupsEventListener() {}, pdfFile, "Test loader", new NoopProgressDialog()
         );
         // preload everything
-        loader.doTask();
+        loader.execute();
+        loader.get();
 
         // initialise the main PDF object tree view
         controller.handleOpenDocument(loader);
@@ -107,32 +114,4 @@ private static StructureTreeNode getStructureTreeRootNode(PdfFile pdfFile) {
         tree.setModel(tree.recalculateTreeModel());
         return (StructureTreeNode) tree.getModel().getRoot();
     }
-
-    private static final class DummyProgressDialog implements IProgressDialog {
-
-        @Override
-        public void setMessage(String msg) {
-
-        }
-
-        @Override
-        public void setValue(int value) {
-
-        }
-
-        @Override
-        public void setTotal(int n) {
-
-        }
-
-        @Override
-        public void showErrorDialog(Exception ex) {
-
-        }
-
-        @Override
-        public void setVisible(boolean visible) {
-
-        }
-    }
 }