TextField with Constaints : TextField « Swing JFC « Java





TextField with Constaints

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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