StringIndexOutOfBoundsException on searchtime [LUCENE-2849]

I've been trying to run the example PrecisionRecall.java code from Lucene in Action II (downloaded the code, so its just as in the book). It gives a StringIndexOutOfBoundsException on my machine.

Figured it out. I copied QualityBenchmark and QualityStats from the Lucene source and inserted a debugline to get a view of the argument values in the function that throws the exception.

private String fracFormat(String frac) {
int k = frac.indexOf('.');
String s1 = padd+frac.substring(0,k);
int n = Math.max(k,6);
s1 = s1.substring(s1.length()-n);
return s1 + frac.substring(k);
}

This function assumes that a decimal '.' is being used. However, the PC's we use over here at uni have a different locale using a ',' for decimals. Think you might be able to catch that by using (new DecimalFormatSymbols().getDecimalSeparator()) instead of ('.')?

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Migrated from [LUCENE-2849](https://issues.apache.org/jira/browse/LUCENE-2849) by Jeroen Vuurens, updated Jan 07 2011
Environment:
```
Windows XP
```

Attachments: [LUCENE-2849.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-2849/LUCENE-2849.patch)