TextField with Constaints
/*
Definitive Guide to Swing for Java 2, Second Edition
By John Zukowski
ISBN: 1-893115-78-X
Publisher: APress
*/
import java.awt.Container;
import java.awt.GridLayout;
import java.awt.Toolkit;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.PlainDocument;
public class RangeSample {
public static void main(String args[]) {
JFrame frame = new JFrame("Range Example");
Container content = frame.getContentPane();
content.setLayout(new GridLayout(3, 2));
content.add(new JLabel("Range: 0-255"));
Document rangeOne = new IntegerRangeDocument(0, 255);
JTextField textFieldOne = new JTextField();
textFieldOne.setDocument(rangeOne);
content.add(textFieldOne);
content.add(new JLabel("Range: -100-100"));
Document rangeTwo = new IntegerRangeDocument(-100, 100);
JTextField textFieldTwo = new JTextField();
textFieldTwo.setDocument(rangeTwo);
content.add(textFieldTwo);
content.add(new JLabel("Range: 1000-2000"));
Document rangeThree = new IntegerRangeDocument(1000, 2000);
JTextField textFieldThree = new JTextField();
textFieldThree.setDocument(rangeThree);
content.add(textFieldThree);
frame.setSize(250, 150);
frame.setVisible(true);
}
}
class IntegerRangeDocument extends PlainDocument {
int minimum, maximum;
int currentValue = 0;
public IntegerRangeDocument(int minimum, int maximum) {
this.minimum = minimum;
this.maximum = maximum;
}
public int getValue() {
return currentValue;
}
public void insertString(int offset, String string, AttributeSet attributes)
throws BadLocationException {
if (string == null) {
return;
} else {
String newValue;
int length = getLength();
if (length == 0) {
newValue = string;
} else {
String currentContent = getText(0, length);
StringBuffer currentBuffer = new StringBuffer(currentContent);
currentBuffer.insert(offset, string);
newValue = currentBuffer.toString();
}
try {
currentValue = checkInput(newValue);
super.insertString(offset, string, attributes);
} catch (Exception exception) {
Toolkit.getDefaultToolkit().beep();
}
}
}
public void remove(int offset, int length) throws BadLocationException {
int currentLength = getLength();
String currentContent = getText(0, currentLength);
String before = currentContent.substring(0, offset);
String after = currentContent.substring(length + offset, currentLength);
String newValue = before + after;
try {
currentValue = checkInput(newValue);
super.remove(offset, length);
} catch (Exception exception) {
Toolkit.getDefaultToolkit().beep();
}
}
public int checkInput(String proposedValue) throws NumberFormatException {
int newValue = 0;
if (proposedValue.length() > 0) {
newValue = Integer.parseInt(proposedValue);
}
if ((minimum <= newValue) && (newValue <= maximum)) {
return newValue;
} else {
throw new NumberFormatException();
}
}
}
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