HA11 content - SimpleDB GUI with slow mode

gui/.classpath

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+<?xml version="1.0" encoding="UTF-8"?>
+<classpath>
+	<classpathentry kind="src" path="src"/>
+        <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/>
+	<classpathentry kind="output" path="bin"/>
+</classpath>

gui/.gitignore

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+/bin/
+/doc/

gui/.project

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+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>GuiProjectW11</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.jdt.core.javabuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.jdt.core.javanature</nature>
+	</natures>
+</projectDescription>

gui/src/gui/MainGui.java

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+package gui;
+
+
+import javax.swing.*;
+import java.awt.event.*;
+import java.util.*;
+
+
+/**
+ * a simple GUI that simulates a slow database for name, email entries. For details see constructor {@link MainGui#MainGui() }.
+ * This class provides a simple static {@link #main(String[])} to start/run the GUI window.
+ */
+public class MainGui {
+
+  private JFrame frame = null;
+  private JPanel cp = new JPanel();
+  private JPanel topPanel = new JPanel();
+  private JPanel middlePanel = new JPanel();
+  private JPanel bottomPanel = new JPanel();
+
+  private JTextField tfName = new JTextField("", 20);
+  private JTextField tfMail = new JTextField("", 20);
+
+  private JButton btBack = new JButton("<--");
+  private JButton btForward = new JButton("-->");
+  private JButton btAdd = new JButton("Neu");
+  private ArrayList<DBEntry> database = new ArrayList<DBEntry>();
+
+  private int index = 0;
+
+  private JMenuItem menuNew = new JMenuItem("Neu");
+  private JMenuItem menuEnd = new JMenuItem("Ende");
+
+  /** inner class representing one entry to DB */
+  private class DBEntry {
+    String name;
+    String email;
+  }
+
+  /** inner class to be used for ActionListener back */
+  private class BackAction implements ActionListener {
+    @Override
+    public void actionPerformed(ActionEvent e) {
+      // always save current entry before loading next
+      DBEntry entry = new DBEntry(); // we create a new DBEntry object instead manipulating the
+                                     // existing one to simulate real new reference to a new object.
+      entry.name = tfName.getText();
+      entry.email = tfMail.getText();
+      saveFieldsToDB(entry, index);
+
+      if (index >= 1) {
+        index--;
+        DBEntry entryLoaded = getEntryFromDB(index);
+        tfName.setText(entryLoaded.name);
+        tfMail.setText(entryLoaded.email);
+      }
+    }
+  }
+
+  /** inner class to be used for ActionListener forward */
+  private class ForwardAction implements ActionListener {
+    @Override
+    public void actionPerformed(ActionEvent e) {
+
+      // always save current entry before loading next
+      DBEntry entry = new DBEntry(); // we create a new DBEntry object instead manipulating the
+                                     // existing one to simulate real new reference to a new object.
+      entry.name = tfName.getText();
+      entry.email = tfMail.getText();
+      saveFieldsToDB(entry, index);
+
+      if (index < database.size() - 1) {
+        index++;
+        DBEntry entryLoaded = getEntryFromDB(index);
+        tfName.setText(entryLoaded.name);
+        tfMail.setText(entryLoaded.email);
+      }
+    }
+  }
+
+
+
+  /** inner class to be used for ActionListener exit program */
+  private class EndAction implements ActionListener {
+
+    @Override
+    public void actionPerformed(ActionEvent e) {
+      System.exit(0);
+    }
+  }
+
+  /** inner class to be used for ActionListener add */
+  private class AddAction implements ActionListener {
+
+    @Override
+    public void actionPerformed(ActionEvent e) {
+      // always save current entry before loading next
+      DBEntry entry = new DBEntry(); // we create a new DBEntry object instead manipulating the
+                                     // existing one to simulate real new reference to a new object.
+      entry.name = tfName.getText();
+      entry.email = tfMail.getText();
+      saveFieldsToDB(entry, index);
+
+      addEmptyEntryToDB();
+      index = database.size() - 1;
+      DBEntry entryLoaded = getEntryFromDB(index);
+      tfName.setText(entryLoaded.name);
+      tfMail.setText(entryLoaded.email);
+    }
+  }
+
+
+
+  /** manipulation of DB and simulates slow connection by Thread.wait() */
+  private void saveFieldsToDB(DBEntry entry, int index) {
+    database.set(index, entry);
+    doWait();
+  }
+
+  /** add an empty entry at end of db (quickly) */
+  private void addEmptyEntryToDB() {
+    DBEntry dbEntry = new DBEntry();
+    dbEntry.name = "";
+    dbEntry.email = "";
+    database.add(dbEntry);
+  }
+
+  /** reads from DB (quickly) */
+  private DBEntry getEntryFromDB(int index) {
+    return this.database.get(index);
+  }
+
+
+
+  /** performing a Thread.wait() for 3 sec */
+  private void doWait() {
+    try {
+      synchronized (database) {
+        database.wait(3 * 1000); // simulates "slow" database by waiting 3sec before this Thread
+                                 // continues. wait needs monitor of the object, thus synchronized
+      }
+    } catch (InterruptedException e1) {
+      // intentionally blank; wait did not work or was earlier interrupted. No problem for us.
+    }
+  }
+
+
+  /**
+   * constructor that configures and shows the GUI window. It contains two text inputs for name and
+   * email address and three buttons BACK, ADD and FORWARD. For each button own inner classes are
+   * defined as {@link ActionListener}: {@link BackAction}, {@link ForwardAction }, {@link AddAction
+   * }, which all three call the {@link #doWait()} method, which simulates a slow database. Thus, it
+   * will have an effect to move the code of the ActionListeners to extra Threads in order to keep
+   * the GUI responsive.
+   * 
+   * @see Runnable
+   * @see Thread
+   * @see ActionListener
+   * 
+   */
+  public MainGui() {
+
+    // dummy data to "database"
+    DBEntry e1 = new DBEntry();
+    e1.name = "Max Muster";
+    e1.email = "max.muster@hs-fulda.de";
+    DBEntry e2 = new DBEntry();
+    e2.name = "Jane Doe";
+    e2.email = "jane.doe@somewhere.com";
+    this.database.add(e1);
+    this.database.add(e2);
+
+    // setup the GUI
+    this.frame = new JFrame("SimpleDB");
+    this.frame.setContentPane(this.cp);
+    this.cp.setLayout(new BoxLayout(this.cp, BoxLayout.Y_AXIS));
+
+    this.topPanel.add(new JLabel("Name"));
+    this.topPanel.add(this.tfName);
+    this.middlePanel.add(new JLabel("E-Mail-Adresse"));
+    this.middlePanel.add(this.tfMail);
+    this.cp.add(this.topPanel);
+    this.cp.add(this.middlePanel);
+
+    this.bottomPanel.add(this.btBack);
+    this.bottomPanel.add(this.btAdd);
+    this.bottomPanel.add(this.btForward);
+    this.cp.add(this.bottomPanel);
+
+    // set menu
+    JMenuBar jmb = new JMenuBar();
+    JMenu menu = new JMenu("Datei");
+    this.frame.setJMenuBar(jmb);
+    jmb.add(menu);
+    menu.add(menuNew);
+    menu.addSeparator();
+    menu.add(menuEnd);
+
+    // register all ActionListeners to GUI components
+    this.btBack.addActionListener(new BackAction());
+    this.btForward.addActionListener(new ForwardAction());
+
+    ActionListener actionAdd = new AddAction();
+    this.btAdd.addActionListener(actionAdd);
+    this.menuNew.addActionListener(actionAdd);
+
+    menuEnd.addActionListener(new EndAction());
+
+    // initially show current db fields (of index 0)
+    DBEntry entry = getEntryFromDB(index);
+    tfName.setText(entry.name);
+    tfMail.setText(entry.email);
+
+
+    this.frame.setSize(800, 200);
+    this.frame.setVisible(true);
+  }
+
+  /**
+   * a simple main which only creates an instance of {@link MainGui}.
+   * 
+   * @param args cmd line arguments (ignored)
+   */
+  public static void main(String[] args) {
+    new MainGui();
+  }
+}
+