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Optimize generating numbers for bullets in Word 

Using char[] instead of String improves performance of this
operation considerably, especially in JDK 11+ where StringBuilder
was switched to work on bytes instead of chars.

This is likely only relevant for very large documents, it was visible
in a synthetic test-file from fuzzing.

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1919239 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Dominik Stadler 2024-07-15 05:41:14 +00:00
parent a971751238
commit 719e7154a1
1 changed files with 8 additions and 3 deletions
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11
poi-scratchpad/src/main/java/org/apache/poi/hwpf/converter/NumberFormatter.java
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@ -19,6 +19,7 @@
package org.apache.poi.hwpf.converter;
import java.util.Arrays;
import java.util.Locale;
import org.apache.poi.util.Beta;
@ -28,8 +29,12 @@ import org.apache.poi.util.Beta;
*/
@Beta
public final class NumberFormatter {
private static final String[] ROMAN_LETTERS = { "m", "cm", "d", "cd", "c",
"xc", "l", "xl", "x", "ix", "v", "iv", "i" };
// use char[] instead of String to speed up StringBuilder.append(), especially in JDK 11+
// where StringBuilder internally switched from char[] to byte[]
private static final char[][] ROMAN_LETTERS = Arrays.stream(
new String[] { "m", "cm", "d", "cd", "c", "xc", "l", "xl", "x", "ix", "v", "iv", "i" }).
map(String::toCharArray).
toArray(char[][]::new);
private static final int[] ROMAN_VALUES = { 1000, 900, 500, 400, 100, 90,
50, 40, 10, 9, 5, 4, 1 };
@ -86,7 +91,7 @@ public final class NumberFormatter {
StringBuilder result = new StringBuilder();
for ( int i = 0; i < ROMAN_LETTERS.length; i++ ) {
String letter = ROMAN_LETTERS[i];
char[] letter = ROMAN_LETTERS[i];
int value = ROMAN_VALUES[i];
while ( number >= value ) {
number -= value;