Java Tutorial/Swing Event/Document

Custom Document Filter

import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.DocumentFilter;
class IntegerRangeDocumentFilter extends DocumentFilter {
  public IntegerRangeDocumentFilter() {
  }
  public void insertString(DocumentFilter.FilterBypass fb, int offset, String string,
      AttributeSet attr) throws BadLocationException {
    System.out.println("insert string"+ string);
    System.out.println(offset);
    super.insertString(fb, offset, string, attr);
  }
  public void remove(DocumentFilter.FilterBypass fb, int offset, int length)
      throws BadLocationException {
    System.out.println("remove");
    
    super.remove(fb, offset, length);
  }
  public void replace(DocumentFilter.FilterBypass fb, int offset, int length, String text,
      AttributeSet attrs) throws BadLocationException {
    System.out.println("replace");
    super.replace(fb, offset, length, text, attrs);
  }
}
public class RangeSample {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Range Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JTextField textFieldOne = new JTextField();
    Document textDocOne = textFieldOne.getDocument();
    DocumentFilter filterOne = new IntegerRangeDocumentFilter();
    ((AbstractDocument) textDocOne).setDocumentFilter(filterOne);
    frame.add(textFieldOne);
    frame.setSize(250, 150);
    frame.setVisible(true);
  }
}

Element Walker

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.text.Document;
import javax.swing.text.Element;
import javax.swing.text.ElementIterator;
public class ElementSample {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Element Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    final JTextArea textArea = new JTextArea();
    JScrollPane scrollPane = new JScrollPane(textArea);
    JButton button = new JButton("Show Elements");
    ActionListener actionListener = new ActionListener() {
      public void actionPerformed(ActionEvent actionEvent) {
        Document document = textArea.getDocument();
        ElementIterator iterator = new ElementIterator(document);
        Element element = iterator.first();
        while (element != null) {
          System.out.println(element.getStartOffset());
          element = iterator.next();
        }
      }
    };
    button.addActionListener(actionListener);
    frame.add(scrollPane, BorderLayout.CENTER);
    frame.add(button, BorderLayout.SOUTH);
    frame.setSize(250, 250);
    frame.setVisible(true);
  }
}

extends PlainDocument to create a float value type text field

import java.awt.FlowLayout;
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.PlainDocument;
class JTextFieldFilter extends PlainDocument {
  public static final String FLOAT = "0123456789.";
  protected String acceptedChars = null;
  protected boolean negativeAccepted = false;
  public JTextFieldFilter() {
    this(FLOAT);
  }
  public JTextFieldFilter(String acceptedchars) {
    acceptedChars = acceptedchars;
  }
  public void setNegativeAccepted(boolean negativeaccepted) {
    if (acceptedChars.equals(FLOAT)) {
      negativeAccepted = negativeaccepted;
      acceptedChars += "-";
    }
  }
  public void insertString(int offset, String str, AttributeSet attr) throws BadLocationException {
    if (str == null)
      return;
    for (int i = 0; i < str.length(); i++) {
      if (acceptedChars.indexOf(str.valueOf(str.charAt(i))) == -1)
        return;
    }
    if (acceptedChars.equals(FLOAT) || (acceptedChars.equals(FLOAT + "-") && negativeAccepted)) {
      if (str.indexOf(".") != -1) {
        if (getText(0, getLength()).indexOf(".") != -1) {
          return;
        }
      }
    }
    if (negativeAccepted && str.indexOf("-") != -1) {
      if (str.indexOf("-") != 0 || offset != 0) {
        return;
      }
    }
    super.insertString(offset, str, attr);
  }
}
public class Main extends JFrame {
  public static void main(String[] argv) throws Exception {
    new Main();
  }
  public Main() {
    JTextField tf1b;
    JLabel l1b;
    setLayout(new FlowLayout());
    l1b = new JLabel("only float");
    tf1b = new JTextField(10);
    getContentPane().add(l1b);
    getContentPane().add(tf1b);
    tf1b.setDocument(new JTextFieldFilter(JTextFieldFilter.FLOAT));
    setSize(300, 300);
    setVisible(true);
  }
}

extends PlainDocument to create alpha and numeric value based field field

import java.awt.FlowLayout;
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.PlainDocument;
class JTextFieldFilter extends PlainDocument {
  public static final String ALPHA = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
  public static final String NUMERIC = "0123456789";
  public static final String ALPHA_NUMERIC = ALPHA + NUMERIC;
  protected String acceptedChars = null;
  protected boolean negativeAccepted = false;
  public JTextFieldFilter() {
    this(ALPHA_NUMERIC);
  }
  public JTextFieldFilter(String acceptedchars) {
    acceptedChars = acceptedchars;
  }
  public void setNegativeAccepted(boolean negativeaccepted) {
    if (acceptedChars.equals(ALPHA_NUMERIC)) {
      negativeAccepted = negativeaccepted;
      acceptedChars += "-";
    }
  }
  public void insertString(int offset, String str, AttributeSet attr) throws BadLocationException {
    if (str == null)
      return;
    for (int i = 0; i < str.length(); i++) {
      if (acceptedChars.indexOf(str.valueOf(str.charAt(i))) == -1)
        return;
    }
    if (negativeAccepted) {
      if (str.indexOf(".") != -1) {
        if (getText(0, getLength()).indexOf(".") != -1) {
          return;
        }
      }
    }
    if (negativeAccepted && str.indexOf("-") != -1) {
      if (str.indexOf("-") != 0 || offset != 0) {
        return;
      }
    }
    super.insertString(offset, str, attr);
  }
}
public class Main extends JFrame{
  public static void main(String[] argv) throws Exception {
    new Main();
  }
  public Main() {
    JTextField tf1c;
    JLabel l1c;
    setLayout(new FlowLayout());
    l1c = new JLabel("only float(can be negative)");
    tf1c = new JTextField(10);
    getContentPane().add(l1c);
    getContentPane().add(tf1c);
    JTextFieldFilter jtff = new JTextFieldFilter(JTextFieldFilter.ALPHA_NUMERIC);
    jtff.setNegativeAccepted(true);
    tf1c.setDocument(jtff);
    
    setSize(300,300);
    setVisible(true);
  }
}

Implement a document cleaner that maps lowercase letters to uppercase

import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;

public class Main{
  public static void main(String[] args) {
    DocumentFilter dfilter = new UpperCaseFilter();
    JTextArea jta = new JTextArea();
    ((AbstractDocument) jta.getDocument()).setDocumentFilter(dfilter);
    JFrame frame = new JFrame("UpcaseFilter");
    frame.getContentPane().add(jta, java.awt.BorderLayout.CENTER);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(200, 120);
    frame.setVisible(true);
  }
}
class UpperCaseFilter extends DocumentFilter {
  public void insertString(DocumentFilter.FilterBypass fb, int offset, String text,
      AttributeSet attr) throws BadLocationException {
    fb.insertString(offset, text.toUpperCase(), attr);
  }
  public void replace(DocumentFilter.FilterBypass fb, int offset, int length, String text,
      AttributeSet attr) throws BadLocationException {
    fb.replace(offset, length, text.toUpperCase(), attr);
  }
}

Limit JTextField input to a maximum length

import javax.swing.JTextField;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;
class JTextFieldLimit extends PlainDocument {
  private int limit;
  JTextFieldLimit(int limit) {
    super();
    this.limit = limit;
  }
  public void insertString(int offset, String str, AttributeSet attr)
      throws BadLocationException {
    if (str == null)
      return;
    if ((getLength() + str.length()) <= limit) {
      super.insertString(offset, str, attr);
    }
  }
}
public class Main {
  public static void main(String[] argv) {
    JTextField textfield1 = new JTextField(15);
    textfield1.setDocument(new JTextFieldLimit(10));
  }
}