| Methods Summary |
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| public void | append(java.awt.Color c, java.lang.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
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| public void | appendNaive(java.awt.Color c, java.lang.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
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| 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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| 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;
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| public static void | main(java.lang.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);
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