What my code doesn't get passed by validator?

Question about the task

Path update

Java Syntax, Level 9, Lesson 5

Under discussion

Implement the changePath(String, String) method so that it replaces the jdk version in the path passed in the first method parameter with the version passed in the second parameter, and returns the new path.
The JDK version starts with "jdk" and ends at "/".

Example:
path - "/usr/java/jdk1.8/bin"
JDK version - "jdk-13"
The changePath(path, JDK version) method should return the path "/usr/java/jdk-13/bin".

The main() method is not involved in testing.

Requirements:

The changePath(String, String) method needs to be implemented as outlined in the task conditions.

package en.codegym.task.pro.task09.task0914; /* Path update */ public class Solution { public static void main(String[] args) { String path = "/usr/java/jdk1.8/bin"; String jdk13 = "jdk-13"; System.out.println(changePath(path, jdk13)); } public static String changePath(String path, String jdk) { String[] arr = path.split("\\/"); for(int i = 0; i < arr.length; i++ ){ if (arr[i].contains("jdk")){ arr[i] = jdk; } } return String.join("/", arr); } }

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Gellert Varga

Level 23 , Szekesfehervar, Hungary

4 February 2022, 11:43

It is possible that this line is the problem:

if (arr[i].contains("jdk"))  // but what if the directory name contains these three letters in the middle of the word?

If you have such a path: "usr/java/Directories-jdkVersions/jdk1.8/bin/" the above program will return such a path: "usr/java/jdk-13/jdk-13/bin" but I think the correct return would be: "usr/java/Directories-jdkVersions/jdk-13/bin" The requirement highlights: >>The JDK version starts with "jdk"<< so I think you should not use the contains() method but the startsWith() method. (I should add that this is just a guess on my part, because we old students didn't have the same task, and I can't test it on the validator.)

Lisa

Level 41

4 February 2022, 10:34

What's the purpose of the \\ inside the split regex? Escaping the / is useless. If you intend to split by \ as well, then remember that you need to double escape inside regex expressions in Java (and you'd have to add an alternation operator like \\\\|/ ). But that seems not to be the question here. The problem might be the reconstruction of the path. join will remove a possible trailing slash. If validation tests such a path it'll fail. You could try to add that back if one was there in the orig string

return String.join("/", arr) + (path.endsWith("/") ? "/" : "");

In case that does not do the trick you could try the indexOf substring way... (just to show you how to do the opposite of what you need)

int start = path.indexOf("jdk");
int end = path.indexOf("/", start);
System.out.println(path.substring(start, end));

A last possibility would be replacing using regex

return path.replaceFirst("jdk.*?/", jdk + "/"); // if you want to look for / and \ then the regex is jdk.*?[\\\\/]+