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--- swing:text_fields [2015/05/10 17:23]
gthanos
+++ swing:text_fields [2016/02/26 11:15] (current)
@@ Line 18: / Line 18: @@
   - Ο 2ος κατασκευαστής δημιουργεί το παραπάνω text field που περιέχει το String **"Default text!"**.
-Εκτός του component JTextField υπάρχει και το component [[http://docs.oracle.com/javase/7/docs/api/javax/swing/JPasswordField.html|javax.swing.JPasswordField]] που χρησιμοποιείται για καταχώρηση passwords. Η διαφορά με το JTextField είναι ότι αντί για την εμφάνιση των καταχωρούμενων χαρακτήρων εμφανίζονται τελείες πράγμα που κάνουν αδύνατη την ανάγνωση του περιεχομένου με γυμνό μάτι.
+Εκτός του component JTextField υπάρχει και το component [[http://docs.oracle.com/javase/7/docs/api/javax/swing/JPasswordField.html|javax.swing.JPasswordField]] που χρησιμοποιείται για καταχώρηση //passwords//. Η διαφορά με το JTextField είναι ότι αντί για την εμφάνιση των καταχωρούμενων χαρακτήρων εμφανίζονται τελείες πράγμα που κάνουν αδύνατη την ανάγνωση του περιεχομένου με γυμνό μάτι.
 Σε αναλογία με το text field, ένα text area (υλοποιείται από την κλάση [[http://docs.oracle.com/javase/7/docs/api/javax/swing/JTextArea.html|JTextArea]]) είναι ένα text field το οποίο καταλαμβάνει πολλαπλές γραμμές. Ένα text area ορίζεται ως εξής:
@@ Line 140: / Line 140: @@
 </code>
+===== Παραδείγματα =====
+==== Παράδειγμα 1ο ====
+Παράδειγμα χρήσης των παραπάνω components δίνεται παρακάτω (__απλουστευμένο__ από το [[http://docs.oracle.com/javase/tutorial/uiswing/components/editorpane.html|site της Oracle]]).
+<code java TextSamplerDemo.java>
+package components;
+import javax.swing.*;
+import javax.swing.text.*;
+import java.awt.*;        //for layout managers and more
+import java.awt.event.*;    //for action events
+import java.net.URL;
+import java.io.IOException;
+public class TextSamplerDemo extends JPanel
+               implements ActionListener {
+  private String newline = "\n";
+  protected static final String textFieldString = "JTextField";
+  protected static final String passwordFieldString = "JPasswordField";
+  protected JLabel actionLabel;
+  public TextSamplerDemo() {
+    setLayout(new BorderLayout());
+    //Create a regular text field.
+    JTextField textField = new JTextField(10);
+    textField.setActionCommand(textFieldString);
+    textField.addActionListener(this);
+    //Create a password field.
+    JPasswordField passwordField = new JPasswordField(10);
+    passwordField.setActionCommand(passwordFieldString);
+    passwordField.addActionListener(this);
+    //Create some labels for the fields.
+    JLabel textFieldLabel = new JLabel(textFieldString + ": ");
+    textFieldLabel.setLabelFor(textField);
+    JLabel passwordFieldLabel = new JLabel(passwordFieldString + ": ");
+    passwordFieldLabel.setLabelFor(passwordField);
+    //Create a label to put messages during an action event.
+    actionLabel = new JLabel("Type text in a field and press Enter.");
+    actionLabel.setBorder(BorderFactory.createEmptyBorder(10,0,0,0));
+    //Lay out the text controls and the labels.
+    JPanel textControlsPane = new JPanel();
+    GridBagLayout gridbag = new GridBagLayout();
+    GridBagConstraints c = new GridBagConstraints();
+    textControlsPane.setLayout(gridbag);
+    JLabel[] labels = {textFieldLabel, passwordFieldLabel };
+    JTextField[] textFields = {textField, passwordField };
+    addLabelTextRows(labels, textFields, gridbag, textControlsPane);
+    c.gridwidth = GridBagConstraints.REMAINDER; //last
+    c.anchor = GridBagConstraints.WEST;
+    c.weightx = 1.0;
+    textControlsPane.add(actionLabel, c);
+    textControlsPane.setBorder(
+        BorderFactory.createCompoundBorder(
+                BorderFactory.createTitledBorder("Text Fields"),
+                BorderFactory.createEmptyBorder(5,5,5,5)));
+    //Create a text area.
+    JTextArea textArea = new JTextArea(
+        "This is an editable JTextArea. " +
+        "A text area is a \"plain\" text component, " +
+        "which means that although it can display text " +
+        "in any font, all of the text is in the same font."
+    );
+    textArea.setFont(new Font("Serif", Font.ITALIC, 16));
+    textArea.setLineWrap(true);
+    textArea.setWrapStyleWord(true);
+    JScrollPane areaScrollPane = new JScrollPane(textArea);
+    areaScrollPane.setVerticalScrollBarPolicy(
+            JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
+    areaScrollPane.setPreferredSize(new Dimension(250, 250));
+    areaScrollPane.setBorder(
+      BorderFactory.createCompoundBorder(
+        BorderFactory.createCompoundBorder(
+                BorderFactory.createTitledBorder("Plain Text"),
+                BorderFactory.createEmptyBorder(5,5,5,5)),
+        areaScrollPane.getBorder()));
+    //Put everything together.
+    JPanel leftPane = new JPanel(new BorderLayout());
+    leftPane.add(textControlsPane,
+           BorderLayout.PAGE_START);
+    leftPane.add(areaScrollPane,
+           BorderLayout.CENTER);
+    add(leftPane, BorderLayout.LINE_START);
+  }
+  private void addLabelTextRows(JLabel[] labels,
+                  JTextField[] textFields,
+                  GridBagLayout gridbag,
+                  Container container) {
+    GridBagConstraints c = new GridBagConstraints();
+    c.anchor = GridBagConstraints.EAST;
+    int numLabels = labels.length;
+    for (int i = 0; i < numLabels; i++) {
+      c.gridwidth = GridBagConstraints.RELATIVE; //next-to-last
+      c.fill = GridBagConstraints.NONE;    //reset to default
+      c.weightx = 0.0;             //reset to default
+      container.add(labels[i], c);
+      c.gridwidth = GridBagConstraints.REMAINDER;   //end row
+      c.fill = GridBagConstraints.HORIZONTAL;
+      c.weightx = 1.0;
+      container.add(textFields[i], c);
+    }
+  }
+  public void actionPerformed(ActionEvent e) {
+    String prefix = "You typed \"";
+    if (textFieldString.equals(e.getActionCommand())) {
+      JTextField source = (JTextField)e.getSource();
+      actionLabel.setText(prefix + source.getText() + "\"");
+    } else if (passwordFieldString.equals(e.getActionCommand())) {
+      JPasswordField source = (JPasswordField)e.getSource();
+      actionLabel.setText(prefix + new String(source.getPassword())
+                + "\"");
+    }
+  }
+  /**
+   * Create the GUI and show it.  For thread safety,
+   * this method should be invoked from the
+   * event dispatch thread.
+   */
+  private static void createAndShowGUI() {
+    //Create and set up the window.
+    JFrame frame = new JFrame("TextSamplerDemo");
+    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+    //Add content to the window.
+    frame.add(new TextSamplerDemo());
+    //Display the window.
+    frame.pack();
+    frame.setVisible(true);
+  }
+  public static void main(String[] args) {
+    //Schedule a job for the event dispatching thread:
+    //creating and showing this application's GUI.
+    SwingUtilities.invokeLater(new Runnable() {
+      public void run() {
+         //Turn off metal's use of bold fonts
+		UIManager.put("swing.boldMetal", Boolean.FALSE);
+		createAndShowGUI();
+      }
+    });
+  }
+}
+</code>
+==== Παράδειγμα 2ο ====
+Το 2ο παράδειγμα είναι από το βιβλίο του Savitch.
+<code java ScollBarDemo.java>
+import javax.swing.*;
+import java.awt.*;
+import java.awt.event.*;
+public class ScrollBarDemo extends JFrame implements ActionListener {
+  public static final int WIDTH = 600;
+  public static final int HEIGHT = 400;
+  public static final int LINES = 15;
+  public static final int CHAR_PER_LINE = 30;
+  private JTextArea memoDisplay;
+  private String memo1;
+  private String memo2;
+  public static void main(String[] args)  {
+    ScrollBarDemo gui = new ScrollBarDemo();
+    gui.setVisible(true);
+  }
+  public ScrollBarDemo() {
+    super("Scroll Bars Demo");
+    setSize(WIDTH, HEIGHT);
+    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+    JPanel buttonPanel = new JPanel();
+    buttonPanel.setBackground(Color.LIGHT_GRAY);
+    buttonPanel.setLayout(new FlowLayout());
+    JButton memo1Button = new JButton("Save Memo 1");
+    memo1Button.addActionListener(this);
+    buttonPanel.add(memo1Button);
+    JButton memo2Button = new JButton("Save Memo 2");
+    memo2Button.addActionListener(this);
+    buttonPanel.add(memo2Button);
+    JButton clearButton = new JButton("Clear");
+    clearButton.addActionListener(this);
+    buttonPanel.add(clearButton);
+    JButton get1Button = new JButton("Get Memo 1");
+    get1Button.addActionListener(this);
+    buttonPanel.add(get1Button);
+    JButton get2Button = new JButton("Get Memo 2");
+    get2Button.addActionListener(this);
+    buttonPanel.add(get2Button);
+    add(buttonPanel, BorderLayout.SOUTH);
+    JPanel textPanel = new JPanel();
+    textPanel.setBackground(Color.BLUE);
+    memoDisplay = new JTextArea(LINES, CHAR_PER_LINE);
+    memoDisplay.setBackground(Color.WHITE);
+    JScrollPane scrolledText = new JScrollPane(memoDisplay);
+    scrolledText.setHorizontalScrollBarPolicy(
+    JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
+    scrolledText.setVerticalScrollBarPolicy(
+    JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
+    textPanel.add(scrolledText);
+    add(textPanel, BorderLayout.CENTER);
+  }
+  public void actionPerformed(ActionEvent e) {
+    String actionCommand = e.getActionCommand();
+    if (actionCommand.equals("Save Memo 1"))
+      memo1 = memoDisplay.getText();
+    else if (actionCommand.equals("Save Memo 2"))
+      memo2 = memoDisplay.getText();
+    else if (actionCommand.equals("Clear"))
+      memoDisplay.setText("");
+    else if (actionCommand.equals("Get Memo 1"))
+      memoDisplay.setText(memo1);
+    else if (actionCommand.equals("Get Memo 2"))
+      memoDisplay.setText(memo2);
+    else
+      memoDisplay.setText("Error in memo interface");
+  }
+}
+</code>
+===== Document Listeners =====
+Κάθε component ή κάθε κατηγορία component συνδέεται με κάποιο Listener Interface. Τα παραπάνω text related components συνδέονται με το interface [[http://docs.oracle.com/javase/7/docs/api/javax/swing/event/DocumentListener.html|javax.swing.event.DocumentListener]]. Οι μέθοδοι του συγκεκριμένου interface δίνονται παρακάτω.
+<code java>
+void changedUpdate(DocumentEvent e);
+//Gives notification that an attribute or set of attributes changed.
+void insertUpdate(DocumentEvent e);
+//Gives notification that there was an insert into the document.
+void removeUpdate(DocumentEvent e);
+//Gives notification that a portion of the document has been removed.
+</code>

Αντικειμενοστραφής Προγραμματισμός, Εφαρμογές με χρήση της γλώσσας προγραμματισμού JAVA

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