Java improvements.

UI threading improvements.
Save user/site changes to file.
Ordering of user / site fixes.
Add questions to JSON output.
Bring JSON output format in line with C.

platform-independent/java/algorithm/src/main/java/com/lyndir/masterpassword/impl/MPAlgorithmV0.java

@@ -45,8 +45,6 @@ public class MPAlgorithmV0 extends MPAlgorithm {
         Native.load( MPAlgorithmV0.class, "mpw" );
     }
 
-    public final Version version = MPAlgorithm.Version.V0;
-
     protected final Logger logger = Logger.get( getClass() );
 
     @Nullable

platform-independent/java/gui/src/main/java/com/lyndir/masterpassword/gui/GUI.java

@@ -22,7 +22,6 @@ import static com.lyndir.lhunath.opal.system.util.StringUtils.*;
 
 import com.google.common.base.Charsets;
 import com.google.common.io.ByteSource;
-import com.google.common.io.CharSource;
 import com.lyndir.lhunath.opal.system.logging.Logger;
 import com.lyndir.lhunath.opal.system.util.TypeUtils;
 import com.lyndir.masterpassword.gui.view.PasswordFrame;
@@ -51,6 +50,9 @@ public class GUI implements UnlockFrame.SignInCallback {
     private       PasswordFrame<?, ?> passwordFrame;
 
     public static void main(final String... args) {
+        Thread.setDefaultUncaughtExceptionHandler(
+                (t, e) -> logger.err( e, "Uncaught: %s", e.getLocalizedMessage() ) );
+
         if (Config.get().checkForUpdates())
             checkUpdate();
 

platform-independent/java/gui/src/main/java/com/lyndir/masterpassword/gui/Res.java

@@ -21,7 +21,6 @@ package com.lyndir.masterpassword.gui;
 import static com.lyndir.lhunath.opal.system.util.ObjectUtils.*;
 import static com.lyndir.lhunath.opal.system.util.StringUtils.*;
 
-import com.google.common.base.Throwables;
 import com.google.common.collect.Maps;
 import com.google.common.io.Resources;
 import com.google.common.util.concurrent.JdkFutureAdapters;
@@ -51,16 +50,18 @@ import org.jetbrains.annotations.NonNls;
 public abstract class Res {
 
     private static final int                                   AVATAR_COUNT        = 19;
-    private static final Map<Window, ScheduledExecutorService> executorByWindow = new WeakHashMap<>();
+    private static final Map<Window, ScheduledExecutorService> jobExecutorByWindow = new WeakHashMap<>();
+    private static final Executor                              immediateUiExecutor = new SwingExecutorService( true );
+    private static final Executor                              laterUiExecutor     = new SwingExecutorService( false );
     private static final Logger                                logger              = Logger.get( Res.class );
     private static final Colors                                colors              = new Colors();
 
-    public static Future<?> execute(final Window host, final Runnable job) {
+    public static Future<?> job(final Window host, final Runnable job) {
-        return schedule( host, job, 0, TimeUnit.MILLISECONDS );
+        return job( host, job, 0, TimeUnit.MILLISECONDS );
     }
 
-    public static Future<?> schedule(final Window host, final Runnable job, final long delay, final TimeUnit timeUnit) {
+    public static Future<?> job(final Window host, final Runnable job, final long delay, final TimeUnit timeUnit) {
-        return getExecutor( host ).schedule( () -> {
+        return jobExecutor( host ).schedule( () -> {
             try {
                 job.run();
             }
@@ -70,33 +71,29 @@ public abstract class Res {
         }, delay, timeUnit );
     }
 
-    public static <V> ListenableFuture<V> execute(final Window host, final Callable<V> job) {
+    public static <V> ListenableFuture<V> job(final Window host, final Callable<V> job) {
-        return schedule( host, job, 0, TimeUnit.MILLISECONDS );
+        return job( host, job, 0, TimeUnit.MILLISECONDS );
     }
 
-    public static <V> ListenableFuture<V> schedule(final Window host, final Callable<V> job, final long delay, final TimeUnit timeUnit) {
+    public static <V> ListenableFuture<V> job(final Window host, final Callable<V> job, final long delay, final TimeUnit timeUnit) {
-        ScheduledExecutorService executor = getExecutor( host );
+        ScheduledExecutorService executor = jobExecutor( host );
-        return JdkFutureAdapters.listenInPoolThread( executor.schedule( () -> {
+        return JdkFutureAdapters.listenInPoolThread( executor.schedule( job::call, delay, timeUnit ), executor );
-            try {
-                return job.call();
-            }
-            catch (final Throwable t) {
-                logger.err( t, "Unexpected: %s", t.getLocalizedMessage() );
-                throw Throwables.propagate( t );
-            }
-        }, delay, timeUnit ), executor );
     }
 
-    private static ScheduledExecutorService getExecutor(final Window host) {
+    public static Executor uiExecutor(final boolean immediate) {
-        ScheduledExecutorService executor = executorByWindow.get( host );
+        return immediate? immediateUiExecutor: laterUiExecutor;
+    }
+
+    public static ScheduledExecutorService jobExecutor(final Window host) {
+        ScheduledExecutorService executor = jobExecutorByWindow.get( host );
 
         if (executor == null) {
-            executorByWindow.put( host, executor = Executors.newSingleThreadScheduledExecutor() );
+            jobExecutorByWindow.put( host, executor = Executors.newSingleThreadScheduledExecutor() );
 
             host.addWindowListener( new WindowAdapter() {
                 @Override
                 public void windowClosed(final WindowEvent e) {
-                    ExecutorService executor = executorByWindow.remove( host );
+                    ExecutorService executor = jobExecutorByWindow.remove( host );
                     if (executor != null)
                         executor.shutdownNow();
                 }
@@ -204,7 +201,7 @@ public abstract class Res {
                         font = Font.createFont( Font.TRUETYPE_FONT, Resources.getResource( fontResourceName ).openStream() ) ) );
             }
             catch (final FontFormatException | IOException e) {
-                throw Throwables.propagate( e );
+                throw logger.bug( e );
             }
 
         return font;

platform-independent/java/gui/src/main/java/com/lyndir/masterpassword/gui/SwingExecutorService.java

@@ -0,0 +1,91 @@
+package com.lyndir.masterpassword.gui;
+
+import static com.lyndir.lhunath.opal.system.util.ObjectUtils.*;
+
+import com.google.common.collect.*;
+import java.util.List;
+import java.util.concurrent.*;
+import javax.swing.*;
+import org.jetbrains.annotations.NotNull;
+
+
+/**
+ * @author lhunath, 2018-07-08
+ */
+public class SwingExecutorService extends AbstractExecutorService {
+
+    private final List<Runnable>         pendingCommands = Lists.newLinkedList();
+    private final BlockingQueue<Boolean> terminated      = Queues.newLinkedBlockingDeque( 1 );
+    private final boolean                immediate;
+    private       boolean                shutdown;
+
+    /**
+     * @param immediate Allow immediate execution of the job in {@link #execute(Runnable)} if already on the right thread.
+     *                  If {@code false}, jobs are always posted for later execution on the event thread.
+     */
+    public SwingExecutorService(final boolean immediate) {
+        this.immediate = immediate;
+    }
+
+    @Override
+    public void shutdown() {
+        shutdown = true;
+
+        synchronized (pendingCommands) {
+            if (pendingCommands.isEmpty())
+                terminated.offer( true );
+        }
+    }
+
+    @NotNull
+    @Override
+    public List<Runnable> shutdownNow() {
+        shutdown();
+
+        synchronized (pendingCommands) {
+            return ImmutableList.copyOf( pendingCommands );
+        }
+    }
+
+    @Override
+    public boolean isShutdown() {
+        return shutdown;
+    }
+
+    @Override
+    public boolean isTerminated() {
+        return ifNotNullElse( terminated.peek(), false );
+    }
+
+    @Override
+    public boolean awaitTermination(final long timeout, @NotNull final TimeUnit unit)
+            throws InterruptedException {
+        return ifNotNullElse( terminated.poll( timeout, unit ), false );
+    }
+
+    @Override
+    public void execute(@NotNull final Runnable command) {
+        if (shutdown)
+            throw new RejectedExecutionException( "Executor is shut down." );
+
+        synchronized (pendingCommands) {
+            pendingCommands.add( command );
+        }
+
+        if (immediate && SwingUtilities.isEventDispatchThread())
+            run( command );
+        else
+            SwingUtilities.invokeLater( () -> run( command ) );
+    }
+
+    private void run(final Runnable command) {
+        command.run();
+
+        synchronized (pendingCommands) {
+            pendingCommands.remove( command );
+
+            if (shutdown && pendingCommands.isEmpty())
+                terminated.offer( true );
+        }
+    }
+}

platform-independent/java/gui/src/main/java/com/lyndir/masterpassword/gui/model/MPIncognitoSite.java

@@ -22,6 +22,7 @@ import com.google.common.primitives.UnsignedInteger;
 import com.lyndir.masterpassword.MPAlgorithm;
 import com.lyndir.masterpassword.MPResultType;
 import com.lyndir.masterpassword.model.impl.MPBasicSite;
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
 
@@ -44,6 +45,7 @@ public class MPIncognitoSite extends MPBasicSite<MPIncognitoQuestion> {
         this.user = user;
     }
 
+    @Nonnull
     @Override
     public MPIncognitoUser getUser() {
         return user;

platform-independent/java/gui/src/main/java/com/lyndir/masterpassword/gui/util/FailableCallback.java

@@ -0,0 +1,23 @@
+package com.lyndir.masterpassword.gui.util;
+
+import com.google.common.util.concurrent.FutureCallback;
+import com.lyndir.lhunath.opal.system.logging.Logger;
+
+
+/**
+ * @author lhunath, 2018-07-08
+ */
+public abstract class FailableCallback<T> implements FutureCallback<T> {
+
+    private final Logger logger;
+
+    protected FailableCallback(final Logger logger) {
+        this.logger = logger;
+    }
+
+    @Override
+    public void onFailure(final Throwable t) {
+        logger.err( t, "Future failed." );
+        onSuccess( null );
+    }
+}

platform-independent/java/gui/src/main/java/com/lyndir/masterpassword/gui/view/PasswordFrame.java

@@ -23,11 +23,12 @@ import static com.lyndir.lhunath.opal.system.util.StringUtils.*;
 
 import com.google.common.collect.Iterables;
 import com.google.common.primitives.UnsignedInteger;
-import com.google.common.util.concurrent.*;
+import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.ListenableFuture;
+import com.lyndir.lhunath.opal.system.logging.Logger;
 import com.lyndir.masterpassword.*;
 import com.lyndir.masterpassword.gui.Res;
-import com.lyndir.masterpassword.gui.util.Components;
+import com.lyndir.masterpassword.gui.util.*;
-import com.lyndir.masterpassword.gui.util.UnsignedIntegerModel;
 import com.lyndir.masterpassword.model.MPSite;
 import com.lyndir.masterpassword.model.MPUser;
 import com.lyndir.masterpassword.model.impl.MPFileSite;
@@ -35,7 +36,7 @@ import com.lyndir.masterpassword.model.impl.MPFileUser;
 import java.awt.*;
 import java.awt.datatransfer.StringSelection;
 import java.awt.datatransfer.Transferable;
-import java.awt.event.*;
+import java.awt.event.WindowEvent;
 import java.util.Collection;
 import java.util.stream.Collectors;
 import javax.annotation.Nonnull;
@@ -50,6 +51,8 @@ import javax.swing.event.DocumentListener;
  */
 public abstract class PasswordFrame<U extends MPUser<S>, S extends MPSite<?>> extends JFrame implements DocumentListener {
 
+    private static final Logger logger = Logger.get( PasswordFrame.class );
+
     @SuppressWarnings("FieldCanBeLocal")
     private final Components.GradientPanel       root;
     private final JTextField                     siteNameField;
@@ -96,30 +99,23 @@ public abstract class PasswordFrame<U extends MPUser<S>, S extends MPSite<?>> ex
                                                         siteNameField = Components.textField(), Components.stud(),
                                                         siteActionButton = Components.button( "Add Site" ) );
         siteNameField.getDocument().addDocumentListener( this );
-        siteNameField.addActionListener( new ActionListener() {
+        siteNameField.addActionListener(
-            @Override
+                e -> Futures.addCallback( updatePassword( true ), new FailableCallback<String>( logger ) {
-            public void actionPerformed(final ActionEvent e) {
-                Futures.addCallback( updatePassword( true ), new FutureCallback<String>() {
                     @Override
                     public void onSuccess(@Nullable final String sitePassword) {
+                        if (sitePassword == null)
+                            return;
+
+                        if (currentSite instanceof MPFileSite)
+                            ((MPFileSite) currentSite).use();
+
                         Transferable clipboardContents = new StringSelection( sitePassword );
                         Toolkit.getDefaultToolkit().getSystemClipboard().setContents( clipboardContents, null );
-
-                        SwingUtilities.invokeLater( () -> {
-                            passwordField.setText( null );
-                            siteNameField.setText( null );
-
                         dispatchEvent( new WindowEvent( PasswordFrame.this, WindowEvent.WINDOW_CLOSING ) );
-                        } );
                     }
-
+                }, Res.uiExecutor( false ) ) );
-                    @Override
+        siteActionButton.addActionListener(
-                    public void onFailure(@Nonnull final Throwable t) {
+                e -> {
-                    }
-                } );
-            }
-        } );
-        siteActionButton.addActionListener( e -> {
                     if (currentSite == null)
                         return;
                     if (currentSite instanceof MPFileSite)
@@ -229,10 +225,9 @@ public abstract class PasswordFrame<U extends MPUser<S>, S extends MPSite<?>> ex
             site.setCounter( siteCounter );
         }
 
-        ListenableFuture<String> passwordFuture = Res.execute( this, () -> site.getResult( MPKeyPurpose.Authentication, null, null ) );
+        ListenableFuture<String> passwordFuture = Res.job( this, () ->
-        Futures.addCallback( passwordFuture, new FutureCallback<String>() {
+                site.getResult( MPKeyPurpose.Authentication, null, null ) );
-            @Override
+
-            public void onSuccess(@Nullable final String sitePassword) {
         SwingUtilities.invokeLater( () -> {
             updatingUI = true;
             currentSite = site;
@@ -242,21 +237,24 @@ public abstract class PasswordFrame<U extends MPUser<S>, S extends MPSite<?>> ex
             else
                 siteActionButton.setText( "Add Site" );
             resultTypeField.setSelectedItem( currentSite.getResultType() );
-                    siteVersionField.setSelectedItem( currentSite.getAlgorithm() );
+            siteVersionField.setSelectedItem( currentSite.getAlgorithm().version() );
             siteCounterField.setValue( currentSite.getCounter() );
             siteNameField.setText( currentSite.getName() );
             if (siteNameField.getText().startsWith( siteNameQuery ))
                 siteNameField.select( siteNameQuery.length(), siteNameField.getText().length() );
+            passwordField.setText( null );
+            tipLabel.setText( "Getting password..." );
+
+            Futures.addCallback( passwordFuture, new FailableCallback<String>( logger ) {
+                @Override
+                public void onSuccess(@Nullable final String sitePassword) {
+                    if (sitePassword != null)
+                        tipLabel.setText( "Press [Enter] to copy the password.  Then paste it into the password field." );
 
                     passwordField.setText( sitePassword );
-                    tipLabel.setText( "Press [Enter] to copy the password.  Then paste it into the password field." );
                     updatingUI = false;
-                } );
-            }
-
-            @Override
-            public void onFailure(@Nonnull final Throwable t) {
                 }
+            }, Res.uiExecutor( true ) );
         } );
 
         return passwordFuture;

platform-independent/java/gui/src/main/java/com/lyndir/masterpassword/gui/view/UnlockFrame.java

@@ -153,7 +153,7 @@ public class UnlockFrame extends JFrame {
     boolean checkSignIn() {
         if (identiconFuture != null)
             identiconFuture.cancel( false );
-        identiconFuture = Res.schedule( this, () -> SwingUtilities.invokeLater( () -> {
+        identiconFuture = Res.job( this, () -> SwingUtilities.invokeLater( () -> {
             String fullName       = (user == null)? "": user.getFullName();
             char[] masterPassword = authenticationPanel.getMasterPassword();
 
@@ -186,7 +186,7 @@ public class UnlockFrame extends JFrame {
         signInButton.setEnabled( false );
         signInButton.setText( "Signing In..." );
 
-        Res.execute( this, () -> {
+        Res.job( this, () -> {
             try {
                 user.authenticate( authenticationPanel.getMasterPassword() );
 

platform-independent/java/model/src/main/java/com/lyndir/masterpassword/model/MPSite.java

@@ -21,6 +21,7 @@ package com.lyndir.masterpassword.model;
 import com.google.common.primitives.UnsignedInteger;
 import com.lyndir.masterpassword.*;
 import java.util.Collection;
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
 
@@ -31,41 +32,50 @@ public interface MPSite<Q extends MPQuestion> extends Comparable<MPSite<?>> {
 
     // - Meta
 
+    @Nonnull
     String getName();
 
     void setName(String name);
 
     // - Algorithm
 
+    @Nonnull
     MPAlgorithm getAlgorithm();
 
     void setAlgorithm(MPAlgorithm algorithm);
 
+    @Nonnull
     UnsignedInteger getCounter();
 
     void setCounter(UnsignedInteger counter);
 
+    @Nonnull
     MPResultType getResultType();
 
     void setResultType(MPResultType resultType);
 
+    @Nonnull
     MPResultType getLoginType();
 
     void setLoginType(@Nullable MPResultType loginType);
 
+    @Nonnull
     String getResult(MPKeyPurpose keyPurpose, @Nullable String keyContext, @Nullable String state)
             throws MPKeyUnavailableException, MPAlgorithmException;
 
+    @Nonnull
     String getLogin(@Nullable String state)
             throws MPKeyUnavailableException, MPAlgorithmException;
 
     // - Relations
 
-    MPUser<? extends MPSite<?>> getUser();
+    @Nonnull
+    MPUser<?> getUser();
 
     void addQuestion(Q question);
 
     void deleteQuestion(Q question);
 
+    @Nonnull
     Collection<Q> getQuestions();
 }

platform-independent/java/model/src/main/java/com/lyndir/masterpassword/model/MPUserManager.java

@@ -18,8 +18,7 @@
 
 package com.lyndir.masterpassword.model;
 
-import com.google.common.collect.ImmutableList;
+import com.google.common.collect.*;
-import com.google.common.collect.Maps;
 import java.util.Collection;
 import java.util.Map;
 
@@ -37,7 +36,7 @@ public abstract class MPUserManager<U extends MPUser<?>> {
     }
 
     public Collection<U> getUsers() {
-        return ImmutableList.copyOf( usersByName.values() );
+        return ImmutableSortedSet.copyOf( usersByName.values() );
     }
 
     public U getUserNamed(final String fullName) {

platform-independent/java/model/src/main/java/com/lyndir/masterpassword/model/impl/Changeable.java

@@ -0,0 +1,59 @@
+package com.lyndir.masterpassword.model.impl;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+
+/**
+ * @author lhunath, 2018-07-08
+ */
+public class Changeable {
+
+    private static final ExecutorService changeExecutor = Executors.newSingleThreadExecutor();
+
+    private boolean changed;
+    private boolean batchingChanges;
+
+    void setChanged() {
+        synchronized (changeExecutor) {
+            if (changed)
+                return;
+            changed = true;
+
+            if (batchingChanges)
+                return;
+
+            changeExecutor.submit( () -> {
+                synchronized (changeExecutor) {
+                    if (batchingChanges)
+                        return;
+                    changed = false;
+                }
+
+                onChanged();
+            } );
+        }
+    }
+
+    protected void onChanged() {
+    }
+
+    public void beginChanges() {
+        synchronized (changeExecutor) {
+            batchingChanges = true;
+        }
+    }
+
+    public boolean endChanges() {
+        synchronized (changeExecutor) {
+            batchingChanges = false;
+
+            if (changed) {
+                this.changed = false;
+                setChanged();
+                return true;
+            } else
+                return false;
+        }
+    }
+}

platform-independent/java/model/src/main/java/com/lyndir/masterpassword/model/impl/MPBasicQuestion.java

@@ -31,7 +31,7 @@ import org.jetbrains.annotations.NotNull;
 /**
  * @author lhunath, 2018-05-14
  */
-public abstract class MPBasicQuestion implements MPQuestion {
+public abstract class MPBasicQuestion extends Changeable implements MPQuestion {
 
     private final String       keyword;
     private       MPResultType type;
@@ -56,6 +56,8 @@ public abstract class MPBasicQuestion implements MPQuestion {
     @Override
     public void setType(final MPResultType type) {
         this.type = type;
+
+        setChanged();
     }
 
     @Nonnull
@@ -70,6 +72,13 @@ public abstract class MPBasicQuestion implements MPQuestion {
     @Override
     public abstract MPBasicSite<?> getSite();
 
+    @Override
+    protected void onChanged() {
+        super.onChanged();
+
+        getSite().setChanged();
+    }
+
     @Override
     public int hashCode() {
         return Objects.hashCode( getKeyword() );

platform-independent/java/model/src/main/java/com/lyndir/masterpassword/model/impl/MPBasicSite.java

@@ -26,6 +26,7 @@ import com.lyndir.masterpassword.*;
 import com.lyndir.masterpassword.model.MPQuestion;
 import com.lyndir.masterpassword.model.MPSite;
 import java.util.*;
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import org.jetbrains.annotations.NotNull;
 
@@ -33,7 +34,7 @@ import org.jetbrains.annotations.NotNull;
 /**
  * @author lhunath, 14-12-16
  */
-public abstract class MPBasicSite<Q extends MPQuestion> implements MPSite<Q> {
+public abstract class MPBasicSite<Q extends MPQuestion> extends Changeable implements MPSite<Q> {
 
     private String          name;
     private MPAlgorithm     algorithm;
@@ -56,6 +57,7 @@ public abstract class MPBasicSite<Q extends MPQuestion> implements MPSite<Q> {
         this.loginType = (loginType == null)? algorithm.mpw_default_login_type(): loginType;
     }
 
+    @Nonnull
     @Override
     public String getName() {
         return name;
@@ -64,8 +66,11 @@ public abstract class MPBasicSite<Q extends MPQuestion> implements MPSite<Q> {
     @Override
     public void setName(final String name) {
         this.name = name;
+
+        setChanged();
     }
 
+    @Nonnull
     @Override
     public MPAlgorithm getAlgorithm() {
         return algorithm;
@@ -74,8 +79,11 @@ public abstract class MPBasicSite<Q extends MPQuestion> implements MPSite<Q> {
     @Override
     public void setAlgorithm(final MPAlgorithm algorithm) {
         this.algorithm = algorithm;
+
+        setChanged();
     }
 
+    @Nonnull
     @Override
     public UnsignedInteger getCounter() {
         return counter;
@@ -84,8 +92,11 @@ public abstract class MPBasicSite<Q extends MPQuestion> implements MPSite<Q> {
     @Override
     public void setCounter(final UnsignedInteger counter) {
         this.counter = counter;
+
+        setChanged();
     }
 
+    @Nonnull
     @Override
     public MPResultType getResultType() {
         return resultType;
@@ -94,8 +105,11 @@ public abstract class MPBasicSite<Q extends MPQuestion> implements MPSite<Q> {
     @Override
     public void setResultType(final MPResultType resultType) {
         this.resultType = resultType;
+
+        setChanged();
     }
 
+    @Nonnull
     @Override
     public MPResultType getLoginType() {
         return loginType;
@@ -104,8 +118,11 @@ public abstract class MPBasicSite<Q extends MPQuestion> implements MPSite<Q> {
     @Override
     public void setLoginType(@Nullable final MPResultType loginType) {
         this.loginType = ifNotNullElse( loginType, getAlgorithm().mpw_default_login_type() );
+
+        setChanged();
     }
 
+    @Nonnull
     @Override
     public String getResult(final MPKeyPurpose keyPurpose, @Nullable final String keyContext, @Nullable final String state)
             throws MPKeyUnavailableException, MPAlgorithmException {
@@ -131,6 +148,7 @@ public abstract class MPBasicSite<Q extends MPQuestion> implements MPSite<Q> {
                 keyPurpose, keyContext, type, state );
     }
 
+    @Nonnull
     @Override
     public String getLogin(@Nullable final String state)
             throws MPKeyUnavailableException, MPAlgorithmException {
@@ -141,18 +159,34 @@ public abstract class MPBasicSite<Q extends MPQuestion> implements MPSite<Q> {
     @Override
     public void addQuestion(final Q question) {
         questions.add( question );
+
+        setChanged();
     }
 
     @Override
     public void deleteQuestion(final Q question) {
         questions.remove( question );
+
+        setChanged();
     }
 
+    @Nonnull
     @Override
     public Collection<Q> getQuestions() {
         return Collections.unmodifiableCollection( questions );
     }
 
+    @Nonnull
+    @Override
+    public abstract MPBasicUser<?> getUser();
+
+    @Override
+    protected void onChanged() {
+        super.onChanged();
+
+        getUser().setChanged();
+    }
+
     @Override
     public int hashCode() {
         return Objects.hashCode( getName() );

platform-independent/java/model/src/main/java/com/lyndir/masterpassword/model/impl/MPBasicUser.java

@@ -20,7 +20,7 @@ package com.lyndir.masterpassword.model.impl;
 
 import static com.lyndir.lhunath.opal.system.util.StringUtils.*;
 
-import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSortedSet;
 import com.lyndir.lhunath.opal.system.CodeUtils;
 import com.lyndir.lhunath.opal.system.logging.Logger;
 import com.lyndir.masterpassword.*;
@@ -34,7 +34,7 @@ import javax.annotation.Nullable;
 /**
  * @author lhunath, 2014-06-08
  */
-public abstract class MPBasicUser<S extends MPBasicSite<?>> implements MPUser<S> {
+public abstract class MPBasicUser<S extends MPBasicSite<?>> extends Changeable implements MPUser<S> {
 
     protected final Logger logger = Logger.get( getClass() );
 
@@ -64,6 +64,8 @@ public abstract class MPBasicUser<S extends MPBasicSite<?>> implements MPUser<S>
     @Override
     public void setAvatar(final int avatar) {
         this.avatar = avatar;
+
+        setChanged();
     }
 
     @Nonnull
@@ -81,6 +83,8 @@ public abstract class MPBasicUser<S extends MPBasicSite<?>> implements MPUser<S>
     @Override
     public void setAlgorithm(final MPAlgorithm algorithm) {
         this.algorithm = algorithm;
+
+        setChanged();
     }
 
     @Nullable
@@ -136,7 +140,7 @@ public abstract class MPBasicUser<S extends MPBasicSite<?>> implements MPUser<S>
     public MPMasterKey getMasterKey()
             throws MPKeyUnavailableException {
         if (masterKey == null)
-            throw new MPKeyUnavailableException( "Master key was not yet set." );
+            throw new MPKeyUnavailableException( "Master key was not yet set for: " + this );
 
         return masterKey;
     }
@@ -144,11 +148,15 @@ public abstract class MPBasicUser<S extends MPBasicSite<?>> implements MPUser<S>
     @Override
     public void addSite(final S site) {
         sites.add( site );
+
+        setChanged();
     }
 
     @Override
     public void deleteSite(final S site) {
         sites.remove( site );
+
+        setChanged();
     }
 
     @Nonnull
@@ -160,7 +168,7 @@ public abstract class MPBasicUser<S extends MPBasicSite<?>> implements MPUser<S>
     @Nonnull
     @Override
     public Collection<S> findSites(final String query) {
-        ImmutableList.Builder<S> results = ImmutableList.builder();
+        ImmutableSortedSet.Builder<S> results = ImmutableSortedSet.naturalOrder();
         for (final S site : getSites())
             if (site.getName().startsWith( query ))
                 results.add( site );

platform-independent/java/model/src/main/java/com/lyndir/masterpassword/model/impl/MPFileQuestion.java

@@ -33,19 +33,24 @@ public class MPFileQuestion extends MPBasicQuestion {
     private final MPFileSite site;
 
     @Nullable
-    private String state;
+    private String answerState;
 
     public MPFileQuestion(final MPFileSite site, final String keyword,
-                          @Nullable final MPResultType type, @Nullable final String state) {
+                          @Nullable final MPResultType type, @Nullable final String answerState) {
         super( keyword, ifNotNullElse( type, site.getAlgorithm().mpw_default_answer_type() ) );
 
         this.site = site;
-        this.state = state;
+        this.answerState = answerState;
+    }
+
+    @Nullable
+    public String getAnswerState() {
+        return answerState;
     }
 
     public String getAnswer()
             throws MPKeyUnavailableException, MPAlgorithmException {
-        return getAnswer( state );
+        return getAnswer( answerState );
     }
 
     public void setAnswer(final MPResultType type, @Nullable final String answer)
@@ -53,10 +58,12 @@ public class MPFileQuestion extends MPBasicQuestion {
         setType( type );
 
         if (answer == null)
-            this.state = null;
+            this.answerState = null;
         else
-            this.state = getSite().getState(
+            this.answerState = getSite().getState(
                     MPKeyPurpose.Recovery, getKeyword(), null, getType(), answer );
+
+        setChanged();
     }
 
     @Nonnull

platform-independent/java/model/src/main/java/com/lyndir/masterpassword/model/impl/MPFileSite.java

@@ -20,6 +20,7 @@ package com.lyndir.masterpassword.model.impl;
 
 import com.google.common.primitives.UnsignedInteger;
 import com.lyndir.masterpassword.*;
+import com.lyndir.masterpassword.model.MPSite;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import org.joda.time.Instant;
@@ -29,6 +30,7 @@ import org.joda.time.ReadableInstant;
 /**
  * @author lhunath, 14-12-05
  */
+@SuppressWarnings("ComparableImplementedButEqualsNotOverridden")
 public class MPFileSite extends MPBasicSite<MPFileQuestion> {
 
     private final MPFileUser user;
@@ -77,6 +79,8 @@ public class MPFileSite extends MPBasicSite<MPFileQuestion> {
 
     public void setUrl(@Nullable final String url) {
         this.url = url;
+
+        setChanged();
     }
 
     public int getUses() {
@@ -125,6 +129,8 @@ public class MPFileSite extends MPBasicSite<MPFileQuestion> {
         else
             this.resultState = getState(
                     MPKeyPurpose.Authentication, null, getCounter(), getResultType(), password );
+
+        setChanged();
     }
 
     @Nullable
@@ -141,10 +147,22 @@ public class MPFileSite extends MPBasicSite<MPFileQuestion> {
         else
             this.loginState = getState(
                     MPKeyPurpose.Identification, null, null, getLoginType(), loginName );
+
+        setChanged();
     }
 
+    @Nonnull
     @Override
     public MPFileUser getUser() {
         return user;
     }
+
+    @Override
+    public int compareTo(final MPSite<?> o) {
+        int comparison = (o instanceof MPFileSite)? -getLastUsed().compareTo( ((MPFileSite) o).getLastUsed() ): 0;
+        if (comparison != 0)
+            return comparison;
+
+        return super.compareTo( o );
+    }
 }

platform-independent/java/model/src/main/java/com/lyndir/masterpassword/model/impl/MPFileUser.java

@@ -18,7 +18,6 @@
 
 package com.lyndir.masterpassword.model.impl;
 
-import com.lyndir.lhunath.opal.system.logging.Logger;
 import com.lyndir.masterpassword.*;
 import com.lyndir.masterpassword.model.MPIncorrectMasterPasswordException;
 import com.lyndir.masterpassword.model.MPUser;
@@ -34,9 +33,6 @@ import org.joda.time.ReadableInstant;
 @SuppressWarnings("ComparableImplementedButEqualsNotOverridden")
 public class MPFileUser extends MPBasicUser<MPFileSite> {
 
-    @SuppressWarnings("UnusedDeclaration")
-    private static final Logger logger = Logger.get( MPFileUser.class );
-
     @Nullable
     private byte[]                   keyID;
     private MPMarshalFormat          format;
@@ -101,6 +97,8 @@ public class MPFileUser extends MPBasicUser<MPFileSite> {
 
     public void setFormat(final MPMarshalFormat format) {
         this.format = format;
+
+        setChanged();
     }
 
     public MPMarshaller.ContentMode getContentMode() {
@@ -109,6 +107,8 @@ public class MPFileUser extends MPBasicUser<MPFileSite> {
 
     public void setContentMode(final MPMarshaller.ContentMode contentMode) {
         this.contentMode = contentMode;
+
+        setChanged();
     }
 
     public MPResultType getDefaultType() {
@@ -117,6 +117,8 @@ public class MPFileUser extends MPBasicUser<MPFileSite> {
 
     public void setDefaultType(final MPResultType defaultType) {
         this.defaultType = defaultType;
+
+        setChanged();
     }
 
     public ReadableInstant getLastUsed() {
@@ -125,6 +127,8 @@ public class MPFileUser extends MPBasicUser<MPFileSite> {
 
     public void use() {
         lastUsed = new Instant();
+
+        setChanged();
     }
 
     public void setJSON(final MPJSONFile json) {
@@ -141,8 +145,23 @@ public class MPFileUser extends MPBasicUser<MPFileSite> {
             throws MPIncorrectMasterPasswordException, MPKeyUnavailableException, MPAlgorithmException {
         super.authenticate( masterKey );
 
-        if (keyID == null)
+        if (keyID == null) {
             keyID = masterKey.getKeyID( getAlgorithm() );
+
+            setChanged();
+        }
+    }
+
+    @Override
+    protected void onChanged() {
+        super.onChanged();
+
+        try {
+            save();
+        }
+        catch (final MPKeyUnavailableException | MPAlgorithmException e) {
+            logger.wrn( e, "Couldn't save change." );
+        }
     }
 
     void save()
@@ -152,7 +171,7 @@ public class MPFileUser extends MPBasicUser<MPFileSite> {
 
     @Override
     public int compareTo(final MPUser<?> o) {
-        int comparison = (o instanceof MPFileUser)? getLastUsed().compareTo( ((MPFileUser) o).getLastUsed() ): 0;
+        int comparison = (o instanceof MPFileUser)? -getLastUsed().compareTo( ((MPFileUser) o).getLastUsed() ): 0;
         if (comparison != 0)
             return comparison;
 

platform-independent/java/model/src/main/java/com/lyndir/masterpassword/model/impl/MPJSONAnyObject.java

@@ -18,14 +18,14 @@
 
 package com.lyndir.masterpassword.model.impl;
 
-import com.fasterxml.jackson.annotation.JsonAnyGetter;
+import com.fasterxml.jackson.annotation.*;
-import com.fasterxml.jackson.annotation.JsonAnySetter;
 import java.util.*;
 
 
 /**
  * @author lhunath, 2018-05-14
  */
+@JsonInclude(value = JsonInclude.Include.CUSTOM, valueFilter = MPJSONAnyObject.MPJSONEmptyValue.class)
 class MPJSONAnyObject {
 
     @JsonAnySetter
@@ -35,4 +35,21 @@ class MPJSONAnyObject {
     public Map<String, Object> getAny() {
         return Collections.unmodifiableMap( any );
     }
+
+    @SuppressWarnings("EqualsAndHashcode")
+    public static class MPJSONEmptyValue {
+
+        @Override
+        @SuppressWarnings({ "ChainOfInstanceofChecks", "Contract" })
+        public boolean equals(final Object obj) {
+            if (obj instanceof Collection<?>)
+                return ((Collection<?>) obj).isEmpty();
+            if (obj instanceof Map<?, ?>)
+                return ((Map<?, ?>) obj).isEmpty();
+            if (obj instanceof MPJSONFile.Site.Ext)
+                return ((MPJSONAnyObject) obj).any.isEmpty();
+
+            return obj == null;
+        }
+    }
 }

platform-independent/java/model/src/main/java/com/lyndir/masterpassword/model/impl/MPJSONFile.java

@@ -20,7 +20,10 @@ package com.lyndir.masterpassword.model.impl;
 
 import static com.lyndir.lhunath.opal.system.util.ObjectUtils.*;
 
-import com.fasterxml.jackson.annotation.*;
+import com.fasterxml.jackson.annotation.JsonAutoDetect;
+import com.fasterxml.jackson.annotation.PropertyAccessor;
+import com.fasterxml.jackson.core.util.DefaultPrettyPrinter;
+import com.fasterxml.jackson.core.util.Separators;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.primitives.UnsignedInteger;
 import com.lyndir.lhunath.opal.system.CodeUtils;
@@ -37,18 +40,28 @@ import org.joda.time.Instant;
 /**
  * @author lhunath, 2018-04-27
  */
-@SuppressFBWarnings( "URF_UNREAD_FIELD" )
+@SuppressFBWarnings("URF_UNREAD_FIELD")
 public class MPJSONFile extends MPJSONAnyObject {
 
     protected static final ObjectMapper objectMapper = new ObjectMapper();
 
     static {
-        objectMapper.setSerializationInclusion( JsonInclude.Include.NON_EMPTY );
+        objectMapper.setDefaultPrettyPrinter( new DefaultPrettyPrinter() {
+            private static final long serialVersionUID = 1;
+
+            @Override
+            public DefaultPrettyPrinter withSeparators(final Separators separators) {
+                super.withSeparators( separators );
+                _objectFieldValueSeparatorWithSpaces = separators.getObjectFieldValueSeparator() + " ";
+                return this;
+            }
+        } );
         objectMapper.setVisibility( PropertyAccessor.FIELD, JsonAutoDetect.Visibility.NON_PRIVATE );
     }
 
     public MPJSONFile write(final MPFileUser modelUser)
             throws MPKeyUnavailableException, MPAlgorithmException {
+
         // Section: "export"
         if (export == null)
             export = new Export();
@@ -98,38 +111,27 @@ public class MPJSONFile extends MPJSONAnyObject {
             site.uses = modelSite.getUses();
             site.last_used = MPConstants.dateTimeFormatter.print( modelSite.getLastUsed() );
 
+            if (site.questions == null)
+                site.questions = new LinkedHashMap<>();
+            for (final MPFileQuestion question : modelSite.getQuestions())
+                site.questions.put( question.getKeyword(), new Site.Question() {
+                    {
+                        type = question.getType();
+
+                        if (!export.redacted) {
+                            // Clear Text
+                            answer = question.getAnswer();
+                        } else {
+                            // Redacted
+                            if (question.getType().supportsTypeFeature( MPSiteFeature.ExportContent ))
+                                answer = question.getAnswerState();
+                        }
+                    }
+                } );
+
             if (site._ext_mpw == null)
                 site._ext_mpw = new Site.Ext();
             site._ext_mpw.url = modelSite.getUrl();
-
-            if (site.questions == null)
-                site.questions = new LinkedHashMap<>();
-            //                for (size_t q = 0; q < site.questions_count; ++q) {
-            //                    MPMarshalledQuestion *question = &site.questions[q];
-            //                    if (!question.keyword)
-            //                        continue;
-            //
-            //                    json_object *json_site_question = json_object_new_object();
-            //                    json_object_object_add( json_site_questions, question.keyword, json_site_question );
-            //                    json_object_object_add( json_site_question, "type = question.type;
-            //
-            //                    if (!user.redacted) {
-            //                        // Clear Text
-            //                const char *answerContent = mpw_siteResult( masterKey, site.name, MPCounterValueInitial,
-            //                                                            MPKeyPurposeRecovery, question.keyword, question.type, question.content, site.algorithm );
-            //                        json_object_object_add( json_site_question, "answer = answerContent;
-            //                    }
-            //                    else {
-            //                        // Redacted
-            //                        if (site.type & MPSiteFeatureExportContent && question.content && strlen( question.content ))
-            //                            json_object_object_add( json_site_question, "answer = question.content;
-            //                    }
-            //                }
-
-            //                json_object *json_site_mpw = json_object_new_object();
-            //                fileSite._ext_mpw = json_site_mpw;
-            //                if (site.url)
-            //                    json_object_object_add( json_site_mpw, "url", site.url );
         }
 
         return this;
@@ -143,6 +145,7 @@ public class MPJSONFile extends MPJSONAnyObject {
                 (user.default_type != null)? user.default_type: algorithm.mpw_default_result_type(),
                 (user.last_used != null)? MPConstants.dateTimeFormatter.parseDateTime( user.last_used ): new Instant(),
                 MPMarshalFormat.JSON, export.redacted? MPMarshaller.ContentMode.PROTECTED: MPMarshaller.ContentMode.VISIBLE );
+        model.beginChanges();
         model.setJSON( this );
         if (masterPassword != null)
             model.authenticate( masterPassword );
@@ -167,6 +170,7 @@ public class MPJSONFile extends MPJSONAnyObject {
 
             model.addSite( site );
         }
+        model.endChanges();
 
         return model;
     }
@@ -193,26 +197,26 @@ public class MPJSONFile extends MPJSONAnyObject {
         String full_name;
         String last_used;
         @Nullable
-        MPAlgorithm.Version algorithm;
-        @Nullable
         String              key_id;
         @Nullable
+        MPAlgorithm.Version algorithm;
+        @Nullable
         MPResultType        default_type;
     }
 
 
     public static class Site extends MPJSONAnyObject {
 
+        @Nullable
+        MPResultType type;
         long                counter;
         MPAlgorithm.Version algorithm;
         @Nullable
-        MPResultType type;
-        @Nullable
         String       password;
         @Nullable
-        MPResultType login_type;
-        @Nullable
         String       login_name;
+        @Nullable
+        MPResultType login_type;
 
         int uses;
         @Nullable

platform-independent/java/model/src/main/java/com/lyndir/masterpassword/model/impl/MPJSONMarshaller.java

@@ -37,7 +37,7 @@ public class MPJSONMarshaller implements MPMarshaller {
             throws MPKeyUnavailableException, MPMarshalException, MPAlgorithmException {
 
         try {
-            return objectMapper.writeValueAsString( user.getJSON().write( user ) );
+            return objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString( user.getJSON().write( user ) );
         }
         catch (final JsonProcessingException e) {
             throw new MPMarshalException( "Couldn't compose JSON for: " + user, e );