How to loop through a string ArrayList and create temporary Character Arrays of each word in the String ArrayList

Question

Lets say I have an ArrayList called dictArray that holds 5 words. The five words are listed as so {"aaron", "abates", "dog", "mellon", "zoo"} . I need to loop through this string ArrayList one word at a time, and for each word create a ArrayList<Character> tempArray to store only the unique characters within that word. (I only need to go one word at a time because I will be performing calculations on the tempArray within the for loop). For example, each iteration would return the following:

{a,r,o,n} {a,b,t,e,s} {d,o,g} {m,e,l,o,n} {z,o}

This block of code will successfully store only the unique characters of the subject word:

 if(tempArray.contains(word.charAt(i))){
   } else {
      tempArray.add(word.charAt(i));
      }
  }

My question: How do I set up the for loop structure to go one word at time, and then after identifying the word, go one letter at a time to call the above if statement? Here is my current code but I am receiving the error message type of expression must be an array type but resolved to ArrayList<String> underneath all of the j 's.

ArrayList<String> dictArray = new ArrayList<String>();
ArrayList<Character> tempArray = new ArrayList<Character>();
for (int i = 0; i < dictArray.size(); i++) { 
    for (j = 0; j < dictArray[j]; j++) {
        if(tempArray.contains(word.charAt(i))){
        } else {
            tempArray.add(word.charAt(i));
        }
    }
}

Answer 1

This is your code with a better format, and I will go down line by line.

ArrayList<String> dictArray = new ArrayList<String>();
ArrayList<Character> tempArray = new ArrayList<Character>();
for (int i = 0; i < dictArray.size(); i++) { 
    for (j = 0; j < dictArray[j]; j++) {
        if(tempArray.contains(word.charAt(i))){
        } else {
            tempArray.add(word.charAt(i));
        }
    }
}

Line 4: for (j = 0; j < dictArray[j]; j++) { , if you want to access an element in the ArrayList, use get(int index). Also, you should use dictArray.get(i) instead of j (which you did not initialize). i is the index of String in the ArrayList, while j should be the index of characters in the String.

Line 5 - 8: can be combined together. You want to add the character if it is not in the tempArray so you don't need to use an if-else statement. Also, you never initialized word, which I think you meant dictArray.get(i)

Last I think you want to add the tempArray to a new ArrayList (call it answer) of Array of Strings which contains the unique characters for each word.

So here is the modified code

ArrayList<ArrayList<Character>> answer = new ArrayList<>();
for (int i = 0; i < dictArray.size(); i++) { 
    ArrayList<Character> tempArray = new ArrayList<Character>();
    for (int j = 0; j < dictArray.get(i).length(); j++) {
        if(!tempArray.contains(dictArray.get(i).charAt(j))){
            tempArray.add(dictArray.get(i).charAt(j));
        }
    }
    answer.add(tempArray);
}

Answer 2

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Test {

    public static void main(String[] args) {

        List<String> dictArray = Arrays.asList("aaron", "abates", "dog", "mellon", "zoo");
        List<List<Character>> result = new ArrayList<>();
        dictArray.stream().
                forEach(word -> {
                    List<Character> charArray = new ArrayList<>();
                    for (Character c : word.toCharArray()) {
                        if (!charArray.contains(c)) {
                            charArray.add(c);
                        }
                    }
                    result.add(charArray);
                });
        System.out.println(result);
    }
}

output :

[[a, r, o, n], [a, b, t, e, s], [d, o, g], [m, e, l, o, n], [z, o]]

Answer 3

you can use a for each to loop through the list and break the individuals down to char arrays and then loop through those

for (String s : arr ) {
            char[] cArray = s.toCharArray();
            for (char cs : cArray) {
                // Your Logic Here
            }
        }

Answer 4

ArrayList s need the get() method to extract a particular value. It might also be helpful to learn about the foreach lop, given here by for(char c: tempArray) . Basically, it means for every character given a variable name c in the list tempArray

for(int i = 0; i < dictArray.size(); i++)
{
    ArrayList<Character> tempArray = new ArrayList<Character>();
    String val = dictArray.get(i);
    for(int j = 0; j < val.length(); j++)
    {  
        if(!tempArray.contains(val.charAt(j)))
        {
            tempArray.add(val.charAt(j));
        }
    }
    String word = "";
    for(char c: tempArray)
    {
        word += c;
    }
    dictArray.add(word);
}

This approach converts tempArray to a String word and stores it in dictArray