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https://issues.apache.org/jira/browse/LANG-810?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13411325#comment-13411325
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Krzysztof Nazarewski edited comment on LANG-810 at 7/11/12 9:17 AM:
--------------------------------------------------------------------
Basically {{endIndex}} takes values from 1 to array.length instead of from 0 to
{{(array.length - 1)}}
In current state {{endIndex}} is "1-based index", not "0-based index" while
Java language uses 0-based indexes, also previous argument {{startIndex}} is
0-based.
If you put valid endIndex 0, the for loop won't run at all as it checks (i <
endIndex) like it was array's length.
Let's say you have 1 element array to join (it does not make practical sense,
bu should work), it has index 0 and does not have anything beyond 0 index.
According to JavaDoc only possible combination of startIndex and endIndex would
be (0,0).
{{StringUtils.java, line 3394: for (int i = startIndex; i < endIndex; i++) {}}
However for loop will not execute even single time because {{(i = startIndex =
0)}} is not lower than {{(endIndex = 0)}}, it is equal to endIndex and the
result of joining single element array from it's only index 0 to index 0 will
be empty string.
Therefore to join that one-element array you need to use combination
{{(startIndex = 0, endIndex = 1)}}, where {{(endIndex == array.length)}} is
error according to JavaDoc:
"endIndex - the index to stop joining from (exclusive). *It is an error to pass
in an end index past the end of the array*"
Let's make some examples:
{code:title="test.java"}
import org.apache.commons.lang3.StringUtils;
public class Test {
public static void main(String[] args) {
String[] array = new String[] { "0", "1", "2", "3" }; //
4-element
// array, which
// has indexes
// from 0 to 3
int startIndex = 0;
int endIndex = 0;
String str = StringUtils.join(array, ",", startIndex, endIndex);
System.out.println("StringUtils.join(array, \",\", " +
startIndex + ", " + endIndex + "); array[" + startIndex
+ "] == " + array[startIndex] + " array[" +
endIndex + "] == " + array[endIndex] + "\n" + str);
startIndex = 0;
endIndex = 1;
str = StringUtils.join(array, ",", startIndex, endIndex);
System.out.println("StringUtils.join(array, \",\", " +
startIndex + ", " + endIndex + "); array[" + startIndex
+ "] == " + array[startIndex] + " array[" +
endIndex + "] == " + array[endIndex] + "\n" + str);
startIndex = 1;
endIndex = 1;
str = StringUtils.join(array, ",", startIndex, endIndex);
System.out.println("StringUtils.join(array, \",\", " +
startIndex + ", " + endIndex + "); array[" + startIndex
+ "] == " + array[startIndex] + " array[" +
endIndex + "] == " + array[endIndex] + "\n" + str);
startIndex = 2;
endIndex = 2;
str = StringUtils.join(array, ",", startIndex, endIndex);
System.out.println("StringUtils.join(array, \",\", " +
startIndex + ", " + endIndex + "); array[" + startIndex
+ "] == " + array[startIndex] + " array[" +
endIndex + "] == " + array[endIndex] + "\n" + str);
startIndex = 0;
endIndex = 3;
str = StringUtils.join(array, ",", startIndex, endIndex);
System.out.println("StringUtils.join(array, \",\", " +
startIndex + ", " + endIndex + "); array[" + startIndex
+ "] == " + array[startIndex] + " array[" +
endIndex + "] == " + array[endIndex] + "\n" + str);
startIndex = 0;
endIndex = 4;
str = StringUtils.join(array, ",", startIndex, endIndex);
System.out.println("StringUtils.join(array, \",\", " +
startIndex + ", " + endIndex + "); array[" + startIndex
+ "] == " + array[startIndex] + " array[" +
endIndex + "] == " + array[endIndex] + "\n" + str); // index
// beyond
// boundaries
// of
// array
}
}
{code}
Run it and tell me what is wrong.
was (Author: drag0nius):
Basically {{endIndex}} takes values from 1 to array.length instead of from
0 to {{(array.length - 1)}}
In current state {{endIndex}} is "1-based index", not "0-based index" while
Java language uses 0-based indexes, also previous argument {{startIndex}} is
0-based.
If you put valid endIndex 0, the for loop won't run at all as it checks (i <
endIndex) like it was array's length.
Let's say you have 1 element array to join (it does not make practical sense,
bu should work), it has index 0 and does not have anything beyond 0 index.
According to JavaDoc only possible combination of startIndex and endIndex would
be (0,0).
{{StringUtils.java, line 3394: for (int i = startIndex; i < endIndex; i++) {}}
However for loop will not execute even single time because {{(i = startIndex =
0)}} is not lower than {{(endIndex = 0)}}, it is equal to endIndex and the
result of joining single element array from it's only index 0 to index 0 will
be empty string.
Therefore to join that one-element array you need to use combination
{{(startIndex = 0, endIndex = 1)}}, where {{(endIndex == array.length)}} is
error according to JavaDoc:
"endIndex - the index to stop joining from (exclusive). *It is an error to pass
in an end index past the end of the array*"
Let's make some examples:
{code:title="test.java"}
import org.apache.commons.lang3.StringUtils;
public class Test {
public static void main(String[] args) {
String[] array = new String[] {"0", "1", "2", "3"}; //
4-element array, which has indexes from 0 to 3
int startIndex = 0;
int endIndex = 0;
String str = StringUtils.join(array, ",", startIndex, endIndex);
System.out.println("1: " + str + "\n\tarray[" + startIndex + "]
== " + array[startIndex] + "\tarray[" + endIndex + "] == " + array[endIndex]);
startIndex = 0;
endIndex = 1;
str = StringUtils.join(array, ",", startIndex, endIndex);
System.out.println("2: " + str + "\n\tarray[" + startIndex + "]
== " + array[startIndex] + "\tarray[" + endIndex + "] == " + array[endIndex]);
startIndex = 1;
endIndex = 1;
str = StringUtils.join(array, ",", startIndex, endIndex);
System.out.println("3: " + str + "\n\tarray[" + startIndex + "]
== " + array[startIndex] + "\tarray[" + endIndex + "] == " + array[endIndex]);
startIndex = 2;
endIndex = 2;
str = StringUtils.join(array, ",", startIndex, endIndex);
System.out.println("4: " + str + "\n\tarray[" + startIndex + "]
== " + array[startIndex] + "\tarray[" + endIndex + "] == " + array[endIndex]);
startIndex = 0;
endIndex = 3;
str = StringUtils.join(array, ",", startIndex, endIndex);
System.out.println("5: " + str + "\n\tarray[" + startIndex + "]
== " + array[startIndex] + "\tarray[" + endIndex + "] == " + array[endIndex]);
startIndex = 0;
endIndex = 4;
str = StringUtils.join(array, ",", startIndex, endIndex);
System.out.println("6: " + str + "\n\tarray[" + startIndex + "]
== " + array[startIndex] + "\tarray[" + endIndex + "] == " + array[endIndex]);
// index beyond boundaries of array
}
}
{code}
will output:
{code}
1:
array[0] == 0 array[0] == 0
2: 0,1
array[0] == 0 array[1] == 1
3:
array[1] == 1 array[1] == 1
4:
array[2] == 2 array[2] == 2
5: 0,1,2,3
array[0] == 0 array[3] == 3
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4
at org.apache.commons.lang3.StringUtils.join(StringUtils.java:3398)
at Test.main(Test.java:28)
{code}
> StringUtils.join() endIndex, bugged for loop
> --------------------------------------------
>
> Key: LANG-810
> URL: https://issues.apache.org/jira/browse/LANG-810
> Project: Commons Lang
> Issue Type: Bug
> Components: lang.*
> Affects Versions: 3.1
> Reporter: Krzysztof Nazarewski
> Assignee: Joerg Schaible
> Original Estimate: 1m
> Remaining Estimate: 1m
>
> endIndex is described as index, but for loop still checks it as "array
> length".
> Basically missing equal sign
> commons-lang3-3.1-sources.jar, StringUtils.java lines 3309, 3394:
> for (int i = startIndex; i < endIndex; i++) {
> should be:
> for (int i = startIndex; i <= endIndex; i++) {
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