Create, compile and test Java function to translate String letter by letter

I need you to create a function in Java translate_string(), which is doing "translation" of the string letter by letter. Function takes String as arg, and returns array of String[]: public static String[] translate_string(String string) Given existing function translate_letter(), which takes String as arg and returns array of String[] public static String[] translate_letter(String letter) and it translating each letter, you need to sequentially translate the whole string letter by letter into combination of output strings. Complexity is, that one character could be translated to multiple sets of characters, it is not one-to-one relationship between input string and output string, it is - one-to-many relationship, where one letter as input could produce multiple combinations (i.e. arrays) as output. N.B.: Term translation has nothing to do with actual translation from one language to another, it is just substitution of one character to set of other characters. Below is exact code id simplified version of function translate_letter() (no modification is required): //------------------------------------------------------------ // translate letters - return array of diff combinations public static String[] translate_letter(String s) { ArrayList<String> o = new ArrayList<>(1); if ( [login to view URL]("a") ) { // if a [login to view URL]("a1"); } else { if ( [login to view URL]("b") ) { // if b [login to view URL]("b1"); [login to view URL]("b2"); } else { if ( [login to view URL]("c") ) { // if c [login to view URL]("c1"); [login to view URL]("c2"); [login to view URL]("c3"); } else { if ( [login to view URL]("d") ) { // if d [login to view URL]("d1"); [login to view URL]("d2"); [login to view URL]("d3"); [login to view URL]("d4"); } else { [login to view URL](s); // s = def add (if nothing above matches) } // end if d } // end if c } // end if b } // end if a //Convert ArrayList o to string array[] String[] array = [login to view URL](new String[[login to view URL]()]); return array; } // end translate_letter() //------------------------------------------------------------ So, how to translate? Let's have a look at simple version of translate - when translate_letter() return just string. So, letter "a" will be translated to "a1", letter "b" will be translated to "b1", "c" - to "c1". Input string "a" will be translated as "a1", simple. Input string "ab" will be translated as "a1b1", simple. Input string "abc" will be translated as "a1b1c1", simple. I don't need to create this simple version - it is nothing to do here. What I need you to write - is complicated version of translate_string(), when function translate_letter() returns multiple combinations, i.e. - array of output combinations. For example (according to the code of translate_letter() above, letter "a" will be translated to "a1", simple. But letter "b" will be translated by translate_letter() to 2 combinations: "b1" and "b2", and output is String[] array = {"b1", "b2" } So, string "a" will be translated by translate_string() as array of just 1 element R[] = { "a1" } String "ab" will be translated as array of 2 elements R[] = { "a1b1", "a1b2" } String "abc" will be translated as: R[] = { "a1b1c1", "a1b1c2", "a1b1c3", "a1b2c1", "a1b2c2", "a1b2c3" } String "db" will be translated as: R[] = { "d1b1", "d2b1", "d3b1", "d4b1" } Note, that actual sequence of individual You can use any data structure, supported by Java 11 and below - Array, 2-dimensional array, ArrayList, Vector, Hash, Map, Tree, Trie, etc, as soon as it is doing the correct translation. Preferable - use ArrayList as data structure, but it could be any, but code needs to be documented to explain what all major steps are doing.