Using Optional<T> semantics for 'replacedLib' in LibraryInstaller

Optional<T> helps to not forget to check about nullness where it is
needed.

This commit should be equivalent and shouln't fix any bug, BTW the
Optional<T> semantic turns out to be useful in the next commits.

Possibly all nullable values will be replaced by Optional in the
future.

app/src/cc/arduino/contributions/libraries/ui/ContributedLibraryReleases.java

@@ -37,6 +37,7 @@ import cc.arduino.contributions.ui.FilteredAbstractTableModel;
 import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Optional;
 import java.util.stream.Collectors;
 
 public class ContributedLibraryReleases {
@@ -76,15 +77,15 @@ public class ContributedLibraryReleases {
     selected = getLatest();
   }
 
-  public ContributedLibrary getInstalled() {
+  public Optional<ContributedLibrary> getInstalled() {
     List<ContributedLibrary> installedReleases = releases.stream().filter(new InstalledPredicate()).collect(Collectors.toList());
     Collections.sort(installedReleases, new DownloadableContributionBuiltInAtTheBottomComparator());
 
     if (installedReleases.isEmpty()) {
-      return null;
+      return Optional.empty();
     }
 
-    return installedReleases.get(0);
+    return Optional.of(installedReleases.get(0));
   }
 
   public ContributedLibrary getLatest() {

app/src/cc/arduino/contributions/libraries/ui/ContributedLibraryTableCellEditor.java

@@ -36,6 +36,7 @@ import java.awt.Component;
 import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Optional;
 import java.util.stream.Collectors;
 
 import javax.swing.JComboBox;
@@ -85,7 +86,7 @@ public class ContributedLibraryTableCellEditor extends InstallerTableCell {
 
     setEnabled(true);
 
-    final ContributedLibrary installed = editorValue.getInstalled();
+    final Optional<ContributedLibrary> mayInstalled = editorValue.getInstalled();
 
     List<ContributedLibrary> releases = editorValue.getReleases().stream()
         .filter(new OnlyUpstreamReleasePredicate())
@@ -97,7 +98,7 @@ public class ContributedLibraryTableCellEditor extends InstallerTableCell {
         .filter(new InstalledPredicate()).filter(new BuiltInPredicate())
         .collect(Collectors.toList());
 
-    if (installed != null && !installedBuiltIn.contains(installed)) {
+    if (mayInstalled.isPresent() && !installedBuiltIn.contains(mayInstalled.get())) {
       uninstalledReleases.addAll(installedBuiltIn);
     }
 
@@ -111,8 +112,8 @@ public class ContributedLibraryTableCellEditor extends InstallerTableCell {
     final List<ContributedLibrary> uninstalledNewerReleases = new LinkedList<>();
 
     uninstalledReleases.stream().forEach(input -> {
-      if (installed == null
+      if (!mayInstalled.isPresent()
-          || VersionComparator.greaterThan(installed, input)) {
+          || VersionComparator.greaterThan(mayInstalled.get(), input)) {
         uninstalledPreviousReleases.add(input);
       } else {
         uninstalledNewerReleases.add(input);
@@ -122,18 +123,18 @@ public class ContributedLibraryTableCellEditor extends InstallerTableCell {
     uninstalledPreviousReleases.forEach(editorCell.downgradeChooser::addItem);
 
     editorCell.downgradeChooser
-        .setVisible(installed != null
+        .setVisible(mayInstalled.isPresent()
                     && (!uninstalledPreviousReleases.isEmpty()
                         || uninstalledNewerReleases.size() > 1));
     editorCell.downgradeButton
-        .setVisible(installed != null
+        .setVisible(mayInstalled.isPresent()
                     && (!uninstalledPreviousReleases.isEmpty()
                         || uninstalledNewerReleases.size() > 1));
 
     editorCell.versionToInstallChooser.removeAllItems();
     uninstalledReleases.forEach(editorCell.versionToInstallChooser::addItem);
     editorCell.versionToInstallChooser
-        .setVisible(installed == null && uninstalledReleases.size() > 1);
+        .setVisible(!mayInstalled.isPresent() && uninstalledReleases.size() > 1);
 
     editorCell.setBackground(new Color(218, 227, 227)); // #dae3e3
     return editorCell;
@@ -153,7 +154,7 @@ public class ContributedLibraryTableCellEditor extends InstallerTableCell {
   }
 
   protected void onInstall(ContributedLibrary selected,
-                           ContributedLibrary installed) {
+                           Optional<ContributedLibrary> mayInstalled) {
     // Empty
   }
 

app/src/cc/arduino/contributions/libraries/ui/ContributedLibraryTableCellJPanel.java

@@ -7,6 +7,7 @@ import java.awt.Color;
 import java.awt.Component;
 import java.awt.Dimension;
 import java.awt.Insets;
+import java.util.Optional;
 
 import javax.swing.Box;
 import javax.swing.BoxLayout;
@@ -116,16 +117,16 @@ public class ContributedLibraryTableCellJPanel extends JPanel {
       return;
 
     ContributedLibrary selected = releases.getSelected();
-    ContributedLibrary installed = releases.getInstalled();
+    Optional<ContributedLibrary> mayInstalled = releases.getInstalled();
 
     boolean installable, upgradable;
-    if (installed == null) {
+    if (!mayInstalled.isPresent()) {
       installable = true;
       upgradable = false;
     } else {
       installable = false;
       upgradable = new DownloadableContributionVersionComparator()
-          .compare(selected, installed) > 0;
+          .compare(selected, mayInstalled.get()) > 0;
     }
     if (installable) {
       installButton.setText(tr("Install"));
@@ -151,7 +152,7 @@ public class ContributedLibraryTableCellJPanel extends JPanel {
 
     // Library name...
     desc += format("<b>{0}</b>", name);
-    if (installed != null && installed.isReadOnly()) {
+    if (mayInstalled.isPresent() && mayInstalled.get().isReadOnly()) {
       desc += " Built-In ";
     }
 
@@ -162,8 +163,8 @@ public class ContributedLibraryTableCellJPanel extends JPanel {
     }
 
     // ...version.
-    if (installed != null) {
+    if (mayInstalled.isPresent()) {
-      String installedVer = installed.getParsedVersion();
+      String installedVer = mayInstalled.get().getParsedVersion();
       if (installedVer == null) {
         desc += " " + tr("Version unknown");
       } else {
@@ -172,7 +173,7 @@ public class ContributedLibraryTableCellJPanel extends JPanel {
     }
     desc += "</font>";
 
-    if (installed != null) {
+    if (mayInstalled.isPresent()) {
       desc += " <strong><font color=\"#00979D\">INSTALLED</font></strong>";
     }
 

app/src/cc/arduino/contributions/libraries/ui/LibraryManagerUI.java

@@ -38,6 +38,7 @@ import java.awt.event.ActionListener;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.LinkedList;
+import java.util.Optional;
 import java.util.function.Predicate;
 
 import javax.swing.Box;
@@ -80,11 +81,11 @@ public class LibraryManagerUI extends InstallerJDialog<ContributedLibrary> {
   protected InstallerTableCell createCellEditor() {
     return new ContributedLibraryTableCellEditor() {
       @Override
-      protected void onInstall(ContributedLibrary selectedLibrary, ContributedLibrary installedLibrary) {
+      protected void onInstall(ContributedLibrary selectedLibrary, Optional<ContributedLibrary> mayInstalledLibrary) {
-        if (selectedLibrary.isReadOnly()) {
+        if (selectedLibrary.isReadOnly() && mayInstalledLibrary.isPresent()) {
-          onRemovePressed(installedLibrary);
+          onRemovePressed(mayInstalledLibrary.get());
         } else {
-          onInstallPressed(selectedLibrary, installedLibrary);
+          onInstallPressed(selectedLibrary, mayInstalledLibrary);
         }
       }
 
@@ -212,12 +213,12 @@ public class LibraryManagerUI extends InstallerJDialog<ContributedLibrary> {
     installerThread.start();
   }
 
-  public void onInstallPressed(final ContributedLibrary lib, final ContributedLibrary replaced) {
+  public void onInstallPressed(final ContributedLibrary lib, final Optional<ContributedLibrary> mayReplaced) {
     clearErrorMessage();
     installerThread = new Thread(() -> {
       try {
         setProgressVisible(true, tr("Installing..."));
-        installer.install(lib, replaced, this::setProgress);
+        installer.install(lib, mayReplaced, this::setProgress);
         onIndexesUpdated(); // TODO: Do a better job in refreshing only the needed element
         //getContribModel().updateLibrary(lib);
       } catch (Exception e) {

app/src/processing/app/Base.java

@@ -358,11 +358,11 @@ public class Base {
           System.exit(1);
         }
 
-        ContributedLibrary installed = indexer.getIndex().getInstalled(libraryToInstallParts[0]);
+        Optional<ContributedLibrary> mayInstalled = indexer.getIndex().getInstalled(libraryToInstallParts[0]);
-        if (selected.isReadOnly()) {
+        if (selected.isReadOnly() && mayInstalled.isPresent()) {
-          libraryInstaller.remove(installed, progressListener);
+          libraryInstaller.remove(mayInstalled.get(), progressListener);
         } else {
-          libraryInstaller.install(selected, installed, progressListener);
+          libraryInstaller.install(selected, mayInstalled, progressListener);
         }
       }
 

arduino-core/src/cc/arduino/contributions/libraries/LibrariesIndex.java

@@ -91,14 +91,14 @@ public abstract class LibrariesIndex {
     return types;
   }
 
-  public ContributedLibrary getInstalled(String name) {
+  public Optional<ContributedLibrary> getInstalled(String name) {
     List<ContributedLibrary> installedReleases = find(name).stream().filter(new InstalledPredicate()).collect(Collectors.toList());
     Collections.sort(installedReleases, new DownloadableContributionBuiltInAtTheBottomComparator());
 
     if (installedReleases.isEmpty()) {
-      return null;
+      return Optional.empty();
     }
 
-    return installedReleases.get(0);
+    return Optional.of(installedReleases.get(0));
   }
 }

arduino-core/src/cc/arduino/contributions/libraries/LibraryInstaller.java

@@ -43,6 +43,7 @@ import processing.app.helpers.FileUtils;
 import java.io.File;
 import java.io.IOException;
 import java.net.URL;
+import java.util.Optional;
 
 import static processing.app.I18n.tr;
 
@@ -82,7 +83,7 @@ public class LibraryInstaller {
     rescanLibraryIndex(progress, progressListener);
   }
 
-  public synchronized void install(ContributedLibrary lib, ContributedLibrary replacedLib, ProgressListener progressListener) throws Exception {
+  public synchronized void install(ContributedLibrary lib, Optional<ContributedLibrary> mayReplacedLib, ProgressListener progressListener) throws Exception {
     if (lib.isInstalled()) {
       System.out.println(I18n.format(tr("Library is already installed: {0} version {1}"), lib.getName(), lib.getParsedVersion()));
       return;
@@ -119,7 +120,9 @@ public class LibraryInstaller {
 
     // Step 3: Remove replaced library and move installed one to the correct location
     // TODO: Fix progress bar...
-    remove(replacedLib, progressListener);
+    if (mayReplacedLib.isPresent()) {
+      remove(mayReplacedLib.get(), progressListener);
+    }
     File destFolder = new File(libsFolder, lib.getName().replaceAll(" ", "_"));
     tmpFolder.renameTo(destFolder);
     progress.stepDone();
@@ -129,7 +132,7 @@ public class LibraryInstaller {
   }
 
   public synchronized void remove(ContributedLibrary lib, ProgressListener progressListener) throws IOException {
-    if (lib == null || lib.isReadOnly()) {
+    if (lib.isReadOnly()) {
       return;
     }