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This noncompliant code example attempts to trim leading charactersletters from the {{string}}. It fails to accomplish this task because {{Character.isLetter()}} does not work for supplementary and combining characters. \[[Hornig 07|AA. Java References#Hornig 07]\] (sic) |
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// Fails for combining characters
public static String trim_bad2(String string) {
int ch;
for (int i = 0; i < string.length(); i += Character.charCount(ch)) {
int ch = string.codePointAt(i);
if (!Character.isLetter(ch)) {
break;
}
}
return string.substring(i);
}
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public static String trim_good(String string) {
BreakIterator iter = BreakIterator.getCharacterInstance();
iter.setText(string);
for (int i = iter.first(); i != BreakIterator.DONE; i = iter.next()) {
int ch = string.codePointAt(i);
if (!Character.isLetter(ch)) {
break;
}
}
if (i == BreakIterator.DONE) { // Reached first or last text boundary
has been reached
return ""; // The input return "";
was either blank or had only (leading) letters
} else {
return string.substring(i);
}
}
return string;
}
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To perform locale-sensitive String comparisons for searching and sorting, use the java.text.Collator class.
Risk Assessment
Failure Failing to account for supplementary and combining characters can lead to unexpected behavior.
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