Words

The purpose of this exercise is to train you to work with strings.

Estimated workload of this exercise is 60 min.

Description

Please, implement StringUtil class methods:

1. countEqualIgnoreCaseAndSpaces

Method signature:

public static int countEqualIgnoreCaseAndSpaces(String[] words, String sample)

Return the number of words from words array that are equal to sample ignoring characters case and leading and trailing spaces.
If sample is null or words is null or empty, return 0. words is guaranteed to not contain null values.

2. splitWords

Method signature:

public static String[] splitWords(String text)

Split text string into array of words using following separating characters: ",", ".", ";", ":", " ", "?", "!".
For empty string, null string, and string consisting only of separating characters return null

3. convertPath

Method signature:

public static String convertPath(String path, boolean toWin)

Convert path to Unix\Windows path depending on a boolean parameter.

Unix path may start with ~ or /. Every subdirectory must end with / character except the last one. Path elements . and .. refer to current directory and parent directory. Filename doesn't necessarily have the extension.
Unix path examples:

• /folder/../folder/file.txt
• /dev/null
• file.txt
• folder/logs/
• ~/user/some_logs

Windows path may start with C:. Every subdirectory must end with \ character except the last one. Path elements . and .. refer to current directory and parent directory. Filename doesn't necessarily have the extension.
Windows path examples:

• file.txt
• \Program Files\some_file.exe
• .\to_do_list.txt
• C:\Users\..\Cygwin
• .\file

Let's consider Unix ~ path to correspond to Windows C:\User path and vice versa.
Let's consider Unix / root folder (i.e., when the path starts with /) to correspond to Windows C:\ drive and vice versa (but C:\User still corresponds to ~).

If path already corresponds to the required format (for instance, is Windows path when Windows paths is needed and toWin boolean parameter is true) return path.
If path is null, empty, or doesn't correspond to any path format (Unix, Windows), return null.
It is guaranteed that path is either a correct path, or it has some of the following errors:

• More than one ~
• ~ is not at the start
• ~ mixed with \ (~ in Windows path)
• More than one C:
• C: is not at the start
• C: mixed with / (C: in Unix path)
• \ mixed with /

Illegal paths example:

• /folder1/folder2\folder3
• C:\User/root
• /dev/~/
• C:/a/b/c/d
• ~\folder
• ~/~
• ~~
• C:\Folder\Subfolder\C:\

4.joinWords

Method signature:

public static String joinWords(String[] words)

Join words from words array and return as a string in the following format: "[str_1, str_2, ..., str_n]".

If words is null or empty return null. words is guaranteed to not contain null values. words may contain empty strings, ignore them, i. e. don't put them in the resulting string. If words contains only empty strings return null.

Hints

• While implementing the methods you might need to come up with regular expressions. You may consider using regex101.com to easier design of regular expressions.
• You can and should use following methods\classes (click on the name):
  • String.strip
  • String.split
  • String.replaceAll
  • String.replaceFirst
  • String.toLowerCase
  • String.equalsIgnoreCase
  • String.startsWith
  • String.matches
  • String.join
  • StringBuilder
  • StringJoiner
  • StringTokenizer

Examples

You may use main method of StringUtil class to test your implementation.

String[] words = new String[] {"   nice ", "nICE", "nic3"};
String sample = "NICE";
int result = StringUtil.countEqualIgnoreCaseAndSpaces(words, sample); // 2
words = new String[]{" zoOm ", " z oom", " Z O O M "};
sample = "ZOOM";
result = StringUtil.countEqualIgnoreCaseAndSpaces(words, sample); // 1

String text = " go with ...the:;        FLOW ";
String[] result = StringUtil.splitWords(text); // ["go", "with", "the", "FLOW"]
text = ":..,,,::: ;;;      ";
result = StringUtil.splitWords(text); // null

String winPath = "C:\\Program Files\\my_prog_file.py";
String unixPath = StringUtil.convertPath(winPath, false); // "/Program Files/my_prog_file.py"
unixPath = "../script.sh";
winPath = StringUtil.convertPath(unixPath, true); // "..\\script.sh"
unixPath = StringUtil.convertPath(unixPath, false); // "../script.sh"
unixPath = "//home/user/somefile";
winPath = StringUtil.convertPath(unixPath, true); // "C:\\home\\user\\somefile"

String[] words = new String[]{"go", "with", "the", "", "FLOW"};
String result = StringUtil.joinWords(words); // "[go, with, the, FLOW]"