How to add colored text to the document JAVA

This code generate a colored text in JTextPane like this image

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<p>import javax.swing.*;</p><br />
<p>import javax.swing.text.*;</p><br />
<p>import java.awt.Color;</p><br />
<p>public class ColorPane extends JTextPane {</p><br />
<p>public void appendNaive(Color c, String s) { // naive implementation</p><br />
<p>// bad: instiantiates a new AttributeSet object on each call</p><br />
<p>SimpleAttributeSet aset = new SimpleAttributeSet();</p><br />
<p>StyleConstants.setForeground(aset, c);</p><br />
<p>int len = getText().length();</p><br />
<p>setCaretPosition(len); // place caret at the end (with no selection)</p><br />
<p>setCharacterAttributes(aset, false);</p><br />
<p>replaceSelection(s); // there is no selection, so inserts at caret</p><br />
<p>}</p><br />
<p>public void append(Color c, String s) { // better implementation--uses StyleContext</p><br />
<p>StyleContext sc = StyleContext.getDefaultStyleContext();</p><br />
<p>AttributeSet aset = sc.addAttribute(SimpleAttributeSet.EMPTY,</p><br />
<p>StyleConstants.Foreground, c);</p><br />
<p>int len = getDocument().getLength(); // same value as getText().length();</p><br />
<p>setCaretPosition(len);  // place caret at the end (with no selection)</p><br />
<p>setCharacterAttributes(aset, false);</p><br />
<p>replaceSelection(s); // there is no selection, so inserts at caret</p><br />
<p>}</p><br />
<p>public static void main(String argv[]) {</p><br />
<p>ColorPane pane = new ColorPane();</p><br />
<p>for (int n=1; n < = 400; n+=1) {</p><br />
</p><p>if (isPrime(n)) {</p><br />
<p>pane.append(Color.red, String.valueOf(n)+' ');</p><br />
<p>} else if (isPerfectSquare(n)) {</p><br />
<p>pane.append(Color.blue, String.valueOf(n)+' ');</p><br />
<p>} else {</p><br />
<p>pane.append(Color.black, String.valueOf(n)+' ');</p><br />
<p>}</p><br />
<p>}</p><br />
<p>JFrame f = new JFrame("ColorPane example");</p><br />
<p>f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);</p><br />
<p>f.setContentPane(new JScrollPane(pane));</p><br />
<p>f.setSize(600, 400);</p><br />
<p>f.setVisible(true);</p><br />
<p>}</p><br />
<p>public static boolean isPrime(int n) {</p><br />
<p>if (n < 2) return false;</p><br />
</p><p>double max = Math.sqrt(n);</p><br />
<p>for (int j=2; j < = max; j+=1)</p><br />
</p><p>if (n % j == 0) return false; // j is a factor</p><br />
<p>return true;</p><br />
<p>}</p><br />
<p>public static boolean isPerfectSquare(int n) {</p><br />
<p>int j = 1;</p><br />
<p>while (j*j < n  &amp;amp;amp;amp;amp;amp;amp;amp;&amp;amp;amp;amp;amp;amp;amp;amp;  j*j > 0)</p><br />
<p>j += 1;</p><br />
<p>return (j*j == n);</p><br />
<p>}</p><br />
<p>}</p><br />
<p>