JTextField
JTextField is the simplest Swing text component. It is also probably its most
widely used text component. JTextField allows you to edit one line
of text. It is derived from JTextComponent,
which provides the basic functionality common to Swing text components. JTextField uses the Document interface for its model. Three
of JTextField’s constructors are
shown here:
JTextField(int cols) JTextField(String str, int cols) JTextField(String str)
Here, str is the string to be initially presented, and cols is the number of columns in the
text field. If no string is specified, the text field is initially empty. If
the number of columns is not specified, the text field is sized to fit the
specified string.
JTextField generates events in response to user interaction. For example, an ActionEvent is fired when the user
presses enter. A CaretEvent is fired
each time the caret (i.e., the cursor) changes position. (CaretEvent is packaged in javax.swing.event.)
Other events are also possible. In many cases, your program will not need to
handle these events. Instead, you will simply obtain the string currently in
the text field when it is needed. To obtain the text currently in the text
field, call getText( ).
The following example
illustrates JTextField. It creates a
JTextField and adds it to the
content pane. When the user presses enter, an action event is generated. This
is handled by displaying the text in the status window.
// Demonstrate JTextField.
import java.awt.*;
import java.awt.event.*; import javax.swing.*;
/*
<applet code="JTextFieldDemo"
width=300 height=50> </applet>
*/
public class JTextFieldDemo extends JApplet {
JTextField jtf;
public void init() { try {
SwingUtilities.invokeAndWait(
new Runnable() {
public void run() { makeGUI();
}
}
);
} catch (Exception exc) {
System.out.println("Can't create because
of " + exc);
}
}
private void makeGUI() {
//Change to flow layout.
setLayout(new FlowLayout());
//Add text field to content pane.
jtf = new JTextField(15); add(jtf);
jtf.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
//Show text when user presses ENTER.
showStatus(jtf.getText());
}
});
Output from the text field
example is shown here:
Related Topics
Privacy Policy, Terms and Conditions, DMCA Policy and Compliant
Copyright © 2018-2024 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.