LibraryViewer etc.: User interface refinements including feedback when no results are matched or an empty string is provided.

1 files changed, 135 insertions, 18 deletions

diff --git a/src/uk/org/ury/library/viewer/LibraryViewerPanel.java b/src/uk/org/ury/library/viewer/LibraryViewerPanel.java
index d6c2f79..af35149 100644
--- a/src/uk/org/ury/library/viewer/LibraryViewerPanel.java
+++ b/src/uk/org/ury/library/viewer/LibraryViewerPanel.java
@@ -5,9 +5,15 @@ package uk.org.ury.library.viewer;
 
 
 import java.net.URL;
+import java.util.concurrent.ExecutionException;
 
+import javax.swing.JButton;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.JScrollPane;
 import javax.swing.JTable;
 import javax.swing.JTextField;
+import javax.swing.SwingWorker;
 
 import org.swixml.SwingEngine;
 
@@ -15,6 +21,7 @@ import uk.org.ury.frontend.FrontendError;
 import uk.org.ury.frontend.FrontendPanel;
 import uk.org.ury.frontend.HintField;
 import uk.org.ury.library.LibraryTableModel;
+import uk.org.ury.library.exceptions.EmptySearchException;
 
 
 /**
@@ -30,32 +37,28 @@ public class LibraryViewerPanel extends FrontendPanel
    */
   private static final long serialVersionUID = -2441616418398056712L;
  
-  
-  /**
-   * Action method for performing a search, bound by the UI XML
-   * manifest to the search field and button
-   */
-  
-  public void
-  search ()
-  {
-    // TODO: SwingWorker?
-    
-    master.doSearch (searchField.getText ());
-    
-    // This is necessary to force the table to update with the new results.
-    
-    resultsTable.setModel (new LibraryTableModel (master.getLibraryList ()));
-  }
-  
 
   /* Controller of this panel. */
+  
   private LibraryViewer master;
   
+  
   /* Panel widgets exposed by the SwiXML user interface. */
   
   private JTable resultsTable;
+  private JScrollPane resultsPane;
+  private JPanel messagePanel;
+  private JLabel messageLabel;
   private JTextField searchField;
+  private JButton searchButton;
+  
+  
+  /* This contains the last search failure message, for use in 
+   * letting the user know what happened.
+   */
+  
+  private String searchFailureMessage = "ALEX!";
+  
   
   /**
    * Construct a new LibraryViewerPanel.
@@ -112,4 +115,118 @@ public class LibraryViewerPanel extends FrontendPanel
     return "Library Viewer Demo";
   }
 
+  
+  /**
+   * Action method for performing a search, bound by the UI XML
+   * manifest to the search field and button.
+   */
+  
+  public void
+  search ()
+  {
+    /* We can't let the user search while another search is going on, 
+     * but it's not good to let the search "freeze" the UI.
+     * 
+     * Hence the search function disables all sensitive parts of the 
+     * interface and launches a search as a background process.
+     * 
+     * We also swap the results table or no-results panel out for a 
+     * panel that says "Searching...", in the interests of 
+     * user-friendliness.
+     */
+    
+    searchField.setEnabled (false);
+    searchButton.setEnabled (false);
+    resultsPane.setVisible (false);
+    messageLabel.setText ("Searching...");
+    messagePanel.setVisible (true);
+    
+    
+    SwingWorker<Boolean, Void> worker = new SwingWorker<Boolean, Void> ()
+    {
+      /**
+       * Perform a task in a separate thread from event-dispatch.
+       * 
+       * In this case, perform a search.
+       * 
+       * @return  whether or not the search was successful.
+       */
+      
+      @Override
+      public Boolean
+      doInBackground ()
+      {
+        try
+          {
+            master.doSearch (searchField.getText ());
+          }
+        catch (EmptySearchException e)
+          {
+            searchFailureMessage = "Please type in a search term.";
+            return false;
+          }
+        
+        return true;
+      }
+      
+      
+      /**
+       * Perform post-search cleanup and finalisation.
+       */
+      
+      @Override
+      public void
+      done ()
+      {
+        // Figure out whether or not the search succeeded.
+        
+        boolean hasSucceeded = false;
+        
+        try
+          {
+            hasSucceeded = this.get ();
+          }
+        catch (InterruptedException e)
+          {
+            // Ignore
+          }
+        catch (ExecutionException e)
+          {
+            // Ignore
+          }
+        
+        
+          // Force table update with new results.
+  
+          resultsTable.setModel (new LibraryTableModel (master.getLibraryList ()));
+          
+          
+          /* Re-enable widgets and swap panels according to whether 
+           * or not results were found. 
+           */
+          
+          searchField.setEnabled (true);
+          searchButton.setEnabled (true);
+          messagePanel.setVisible (true);
+          
+          if (hasSucceeded == false)
+            {
+              messageLabel.setText (searchFailureMessage);
+            }
+          else if (master.getLibraryList ().size () == 0)
+            {
+              messageLabel.setText ("Sorry, but no results were "
+                                    + "found for that term.");
+            }
+          else
+            {
+              messagePanel.setVisible (false);
+              resultsPane.setVisible (true);            
+            }
+        }
+    };
+    
+    
+    worker.execute ();
+  }
 }