Differences

This shows you the differences between two versions of the page.

--- swing:text_fields [2015/05/10 17:24]
gthanos [Text Fields, Text Areas & Scroll Panes (Scroll Bars)]
+++ swing:text_fields [2016/02/26 11:15] (current)
@@ 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

User Tools

Site Tools

Differences

Page Tools