org.apache.lucene.document
public class: NumberTools [javadoc |
source]
java.lang.Object
org.apache.lucene.document.NumberTools
Provides support for converting longs to Strings, and back again. The strings
are structured so that lexicographic sorting order is preserved.
That is, if l1 is less than l2 for any two longs l1 and l2, then
NumberTools.longToString(l1) is lexicographically less than
NumberTools.longToString(l2). (Similarly for "greater than" and "equals".)
This class handles all long values (unlike
org.apache.lucene.document.DateField ).
| Field Summary |
|---|
| public static final String | MIN_STRING_VALUE | Equivalent to longToString(Long.MIN_VALUE) |
| public static final String | MAX_STRING_VALUE | Equivalent to longToString(Long.MAX_VALUE) |
| public static final int | STR_SIZE | The length of (all) strings returned by #longToString |
| Method from org.apache.lucene.document.NumberTools Detail: |
|---|
 public static String longToString(long l) {
if (l == Long.MIN_VALUE) {
// special case, because long is not symetric around zero
return MIN_STRING_VALUE;
}
StringBuffer buf = new StringBuffer(STR_SIZE);
if (l < 0) {
buf.append(NEGATIVE_PREFIX);
l = Long.MAX_VALUE + l + 1;
} else {
buf.append(POSITIVE_PREFIX);
}
String num = Long.toString(l, RADIX);
int padLen = STR_SIZE - num.length() - buf.length();
while (padLen-- > 0) {
buf.append('0");
}
buf.append(num);
return buf.toString();
}
Converts a long to a String suitable for indexing. |
public static long stringToLong(String str) {
if (str == null) {
throw new NullPointerException("string cannot be null");
}
if (str.length() != STR_SIZE) {
throw new NumberFormatException("string is the wrong size");
}
if (str.equals(MIN_STRING_VALUE)) {
return Long.MIN_VALUE;
}
char prefix = str.charAt(0);
long l = Long.parseLong(str.substring(1), RADIX);
if (prefix == POSITIVE_PREFIX) {
// nop
} else if (prefix == NEGATIVE_PREFIX) {
l = l - Long.MAX_VALUE - 1;
} else {
throw new NumberFormatException(
"string does not begin with the correct prefix");
}
return l;
} Converts a String that was returned by #longToString back to a
long. |
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