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POCleaner way to 'sanitize' JTextField input?
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  1. POCleaner way to 'sanitize' JTextField input?
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    copied!<p>So I'm writing the TextValueChanged handler for a JTextField that takes a long as it's input. It needs to only allow the user to type in valid values between 0 and Long.MAX. If the user types an invalid character, it should strip it, so that the value in the JTextField is always a valid long.</p> <p>My current code looks like this, but it seems ugly. With no external libs (including Apache Commons), is there a cleaner/simpler way to do this?</p> <pre><code>public void textValueChanged(TextEvent e) { if (e.getSource() instanceof JTextField) { String text = ((JTextField) e.getSource()).getText(); try { // Try to parse cleanly long longNum = Long.parseLong(text); // Check for &lt; 1 if (longNum &lt; 1) throw new NumberFormatException(); // If we pass, set the value and return setOption("FIELDKEY", longNum); } catch (NumberFormatException e1) { // We failed, so there's either a non-numeric or it's too large. String s = ((JTextField) e.getSource()).getText(); // Strip non-numeric characters s = s.replaceAll("[^\\d]", ""); long longNum = -1; if (s.length() != 0) { /* Really ugly workaround for the fact that a * TextValueChanged event can capture more than one * keystroke at a time, if it's typed fast enough, * so we might have to strip more than one * character. */ Exception e3; do { e3 = null; try { // Try and parse again longNum = Long.parseLong(s); } catch (NumberFormatException e2) { // We failed, so it's too large. e3 = e2; // Strip the last character and try again. s = s.substring(0, s.length() - 1); } // Repeat } while (e3 != null); } // We parsed, so add it (or blank it if it's &lt; 1) and return. setOption("FIELDKEY", (longNum &lt; 1 ? 0 : longNum)); } } } </code></pre> <p>The field is constantly repopulated from a getOption(key) call, so to 'store' the value, just pass it to that call.</p>
 

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