Extension of JTextPane that allows the user to easily append colored text to the document
/*
Java Swing, 2nd Edition
By Marc Loy, Robert Eckstein, Dave Wood, James Elliott, Brian Cole
ISBN: 0-596-00408-7
Publisher: O'Reilly
*/
// ColorPane.java
//A simple extension of JTextPane that allows the user to easily append
//colored text to the document.
//
import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextPane;
import javax.swing.text.AttributeSet;
import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.StyleConstants;
import javax.swing.text.StyleContext;
public class ColorPane extends JTextPane {
public void appendNaive(Color c, String s) { // naive implementation
// bad: instiantiates a new AttributeSet object on each call
SimpleAttributeSet aset = new SimpleAttributeSet();
StyleConstants.setForeground(aset, c);
int len = getText().length();
setCaretPosition(len); // place caret at the end (with no selection)
setCharacterAttributes(aset, false);
replaceSelection(s); // there is no selection, so inserts at caret
}
public void append(Color c, String s) { // better implementation--uses
// StyleContext
StyleContext sc = StyleContext.getDefaultStyleContext();
AttributeSet aset = sc.addAttribute(SimpleAttributeSet.EMPTY,
StyleConstants.Foreground, c);
int len = getDocument().getLength(); // same value as
// getText().length();
setCaretPosition(len); // place caret at the end (with no selection)
setCharacterAttributes(aset, false);
replaceSelection(s); // there is no selection, so inserts at caret
}
public static void main(String argv[]) {
ColorPane pane = new ColorPane();
for (int n = 1; n <= 400; n += 1) {
if (isPrime(n)) {
pane.append(Color.red, String.valueOf(n) + ' ');
} else if (isPerfectSquare(n)) {
pane.append(Color.blue, String.valueOf(n) + ' ');
} else {
pane.append(Color.black, String.valueOf(n) + ' ');
}
}
JFrame f = new JFrame("ColorPane example");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setContentPane(new JScrollPane(pane));
f.setSize(600, 400);
f.setVisible(true);
}
public static boolean isPrime(int n) {
if (n < 2)
return false;
double max = Math.sqrt(n);
for (int j = 2; j <= max; j += 1)
if (n % j == 0)
return false; // j is a factor
return true;
}
public static boolean isPerfectSquare(int n) {
int j = 1;
while (j * j < n && j * j > 0)
j += 1;
return (j * j == n);
}
}
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