Fix some trivial SonarQube issues

This commit contains the issues, which have trivial fixes and should not
change the application logic itself.

Permissions, IconButton and IconActionListener classes were deleted, as
they were not used anywhere.

Author: Eswcvlad

src/main/java/com/itextpdf/rups/RupsConfiguration.java

@@ -224,34 +224,20 @@ public void setOpenDuplicateFiles(boolean value) {
      * @param newDefaultFolder folder to use
      */
     public void setHomeFolder(String newDefaultFolder) {
-        final String defaultHome = System.getProperty(HOME_FOLDER_KEY);
-        if (newDefaultFolder == null || DEFAULT_HOME_VALUE.equals(newDefaultFolder)) {
-            newDefaultFolder = defaultHome;
-        } else {
-            File valueDirectory = new File(newDefaultFolder);
-            if (!valueDirectory.exists() || !valueDirectory.isDirectory()) {
-                newDefaultFolder = defaultHome;
-            }
-        }
-
-        this.temporaryProperties.setProperty(HOME_FOLDER_KEY, newDefaultFolder);
+        this.temporaryProperties.setProperty(HOME_FOLDER_KEY, sanitizeHomeFolder(newDefaultFolder));
     }
 
     public void setUserLocale(Locale locale) {
-        if (locale == null) {
-            locale = Locale.getDefault();
-        }
-
-        this.temporaryProperties.setProperty(LOCALE_KEY, locale.toLanguageTag());
+        this.temporaryProperties.setProperty(LOCALE_KEY, defaultIfNull(locale).toLanguageTag());
     }
 
     /**
      * Saves any unsaved changes. To cancel changes, see {@link RupsConfiguration#cancelTemporaryChanges()}.
      */
     public void saveConfiguration() {
-        this.temporaryProperties.forEach((key, value) -> {
-            this.systemPreferences.put((String) key, (String) value);
-        });
+        this.temporaryProperties.forEach((Object key, Object value) ->
+            this.systemPreferences.put((String) key, (String) value)
+        );
 
         this.temporaryProperties.clear();
     }
@@ -267,9 +253,9 @@ public void cancelTemporaryChanges() {
      * Resets the settings in Preferences, not the local Properties object to the default.
      */
     public void resetToDefaultProperties() {
-        this.defaultProperties.forEach((Object key, Object value) -> {
-            this.systemPreferences.put((String) key, (String) value);
-        });
+        this.defaultProperties.forEach((Object key, Object value) ->
+            this.systemPreferences.put((String) key, (String) value)
+        );
 
         this.temporaryProperties.clear();
     }
@@ -297,9 +283,9 @@ public Properties getCurrentState() throws BackingStoreException {
      * @param properties Properties holding new values for Preferences
      */
     public void restore(Properties properties) {
-        properties.forEach((key, value) -> {
-            this.systemPreferences.put((String) key, (String) value);
-        });
+        properties.forEach((Object key, Object value) ->
+            this.systemPreferences.put((String) key, (String) value)
+        );
     }
 
     /**
@@ -312,18 +298,14 @@ public MruListHandler getMruListHandler() {
     }
 
     private Properties loadDefaultProperties() {
-        final InputStream resourceAsStream = RupsConfiguration.class.getResourceAsStream(DEFAULT_CONFIG_PATH);
         final Properties properties = new Properties();
-
-        if (resourceAsStream != null) {
-            try {
+        try (final InputStream resourceAsStream = RupsConfiguration.class.getResourceAsStream(DEFAULT_CONFIG_PATH)) {
+            if (resourceAsStream != null) {
                 properties.load(resourceAsStream);
-                resourceAsStream.close();
-            } catch (IOException e) {
-                LoggerHelper.error(Language.ERROR_LOADING_DEFAULT_SETTINGS.getString(), e, RupsConfiguration.class);
             }
+        } catch (IOException e) {
+            LoggerHelper.error(Language.ERROR_LOADING_DEFAULT_SETTINGS.getString(), e, RupsConfiguration.class);
         }
-
         return properties;
     }
 
@@ -357,4 +339,22 @@ private String getValueFromSystemPreferences(String key, String defaultValue) {
     private String getValueFromSystemPreferences(String key) {
         return this.systemPreferences.get(key, this.defaultProperties.getProperty(key));
     }
+
+    private static Locale defaultIfNull(Locale locale) {
+        if (locale == null) {
+            return Locale.getDefault();
+        }
+        return locale;
+    }
+
+    private static String sanitizeHomeFolder(String path) {
+        if (path == null || DEFAULT_HOME_VALUE.equals(path)) {
+            return System.getProperty(HOME_FOLDER_KEY);
+        }
+        final File file = new File(path);
+        if (!file.isDirectory()) {
+            return System.getProperty(HOME_FOLDER_KEY);
+        }
+        return path;
+    }
 }

src/main/java/com/itextpdf/rups/RupsLauncher.java

@@ -52,7 +52,11 @@ This file is part of the iText (R) project.
  * iText RUPS is a tool that allows you to inspect the internal structure
  * of a PDF file.
  */
-public class RupsLauncher {
+public final class RupsLauncher {
+    private RupsLauncher() {
+        // static class
+    }
+
     /**
      * Main method. Starts the RUPS application.
      *

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

@@ -313,15 +313,15 @@ public void render(PdfObjectTreeNode node) {
      * @param pageNumber the page number that needs to be selected
      */
     public void gotoPage(int pageNumber) {
-        pageNumber--;
+        final int rowIndex = pageNumber - 1;
 
         if (pages == null
-                || pages.getSelectedRow() == pageNumber) {
+                || pages.getSelectedRow() == rowIndex) {
             return;
         }
 
-        if (pageNumber < pages.getRowCount()) {
-            pages.setRowSelectionInterval(pageNumber, pageNumber);
+        if (rowIndex < pages.getRowCount()) {
+            pages.setRowSelectionInterval(rowIndex, rowIndex);
         }
     }
 

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

@@ -96,6 +96,7 @@ This file is part of the iText (R) project.
  * instance.
  */
 public class RupsInstanceController implements TreeSelectionListener, PageSelectionListener, IRupsEventListener {
+    private static final String PDF_FILE_SUFFIX = ".pdf";
 
     private final JPanel ownerPanel;
 
@@ -218,9 +219,8 @@ public void saveFile(File file) {
         OutputStream fos = null;
         File localFile = file;
         try {
-            final String pdfSuffix = ".pdf";
-            if (!localFile.getName().endsWith(pdfSuffix)) {
-                localFile = new File(localFile.getPath() + pdfSuffix);
+            if (!localFile.getName().endsWith(PDF_FILE_SUFFIX)) {
+                localFile = new File(localFile.getPath() + PDF_FILE_SUFFIX);
             }
 
             if (localFile.exists()) {

src/main/java/com/itextpdf/rups/io/DefaultSystemViewerAction.java

@@ -50,6 +50,10 @@ This file is part of the iText (R) project.
 import java.io.IOException;
 
 public class DefaultSystemViewerAction implements ISystemViewerAction {
+    public DefaultSystemViewerAction() {
+        // noop
+    }
+
     @Override
     public final boolean isViewingSupported() {
         return Desktop.isDesktopSupported();

src/main/java/com/itextpdf/rups/io/TextAreaOutputStream.java

@@ -51,11 +51,11 @@ This file is part of the iText (R) project.
 /**
  * Everything writing to this OutputStream will be shown in a JTextArea.
  */
-public class TextAreaOutputStream extends OutputStream {
+public final class TextAreaOutputStream extends OutputStream {
     /**
      * The text area to which we want to write.
      */
-    protected JTextArea text;
+    private final JTextArea text;
 
     /**
      * Constructs a TextAreaOutputStream.

src/main/java/com/itextpdf/rups/io/filters/PdfFilter.java

@@ -53,12 +53,17 @@ This file is part of the iText (R) project.
  * Filters PDF files in a {@link JFileChooser}.
  */
 public class PdfFilter extends FileFilter {
+    private static final String PDF_FILE_SUFFIX = ".pdf";
 
     /**
      * A public instance of the PdfFilter.
      */
     public static final PdfFilter INSTANCE = new PdfFilter();
 
+    public PdfFilter() {
+        // noop
+    }
+
     /**
      * @param f File
      *
@@ -67,9 +72,8 @@ public class PdfFilter extends FileFilter {
      * @see FileFilter#accept(java.io.File)
      */
     public boolean accept(File f) {
-        final String suffix = ".pdf";
         return f != null && (f.isDirectory() || f.getName().toLowerCase(RupsConfiguration.INSTANCE.getUserLocale())
-                .endsWith(suffix));
+                .endsWith(PDF_FILE_SUFFIX));
     }
 
     /**

src/main/java/com/itextpdf/rups/io/listeners/PdfTreeExpansionListener.java

@@ -54,6 +54,9 @@ This file is part of the iText (R) project.
  * Listener that checks if the expanded node has one child. If it has one child it should expand it.
  */
 public final class PdfTreeExpansionListener implements TreeExpansionListener {
+    public PdfTreeExpansionListener() {
+        // noop
+    }
 
     @Override
     public void treeExpanded(TreeExpansionEvent event) {

src/main/java/com/itextpdf/rups/io/listeners/PdfTreeNavigationListener.java

@@ -54,6 +54,10 @@ public class PdfTreeNavigationListener implements KeyListener, MouseListener {
 
     private boolean arrowsUsedAsNavigation = false;
 
+    public PdfTreeNavigationListener() {
+        // noop
+    }
+
     public boolean isLastActionKeyboardNavigation() {
         return arrowsUsedAsNavigation;
     }

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

@@ -90,12 +90,6 @@ public boolean isInteractive() {
         return true;
     }
 
-    /*
-     * Ignoring the "Return an empty array instead of null" warning. Here null
-     * means, that the user cancelled password input operation. So it is
-     * different from an empty password.
-     */
-    @SuppressWarnings("java:S1168")
     @Override
     public byte[] get(File originalFile) {
         // originalFile is ignored, since we are using a GUI
@@ -117,6 +111,7 @@ public void selectInitialValue() {
         final Object selectedValue = pane.getValue();
         // If user didn't click OK in the dialog
         if (!(selectedValue instanceof Integer) || (Integer) selectedValue != JOptionPane.OK_OPTION) {
+            // null <=> password dialog was cancelled
             return null;
         }
         return preparePasswordForOpen(new String(passwordField.getPassword()));