Returning index in array from user input string

Question

I'm attempting to achieve a simple sort of hangman situation in Java, where an array of characters is initialized, takes a user input, and returns all indexes where the letters in the string input occurs. So far, I have a very strange output and I think it's due to my beginner's faux pas in terms of my loops and certain placements. Do let me know if you have insight to this issue:

public class ArrayRandomString {
    public static void main(String[] args) {

        // Create an array of characters:
        Character[] anArray = { 'P', 'A', 'P', 'A', 'B', 'E', 'A', 'R' };
        for (char ch : anArray)
            System.out.print(ch + " ");
        System.out.println();

        System.out.println("This program initializes a secret word or phrase to be guessed by you!");
        System.out.println("Enter a string of less than 5 characters to return all indexes where it occurs in scrambled string: ");
        Scanner input = new Scanner(System.in);
        String string = input.next();

        System.out.println(string);
        System.out.println(Character.toUpperCase(string.charAt(0)));

        List<Integer> myList = new ArrayList<Integer>();
        List<Integer> noList = new ArrayList<Integer>();
        int i;
        int j;
        // Loop to find index of inputted character
        for (i = 0; i < anArray.length; i++) {
            Character ch = new Character(anArray[i]);
            for (j = 0; j < string.length(); j++) {
                List<Integer> letterList = new ArrayList<Integer>();
                if (Character.toUpperCase(string.charAt(j)) == ch) {
                    letterList.add(j);
                }
                System.out.println(Character.toUpperCase(string.charAt(j)) + " occurs at the following index " + letterList);
            }
        }
        // System.out.println("Your letter occurs at the following index in the scrambled array. No occurence, if empty: " + myList);
    }
}

If user input is 'PEAR', Ideal Output:

P occurs at [0, 2]
E occurs at [5]
A occurs at [1, 3, 6]
R occurs at [7]

If user input is 'TEA', Ideal Output:

T does not occur in string
E occurs at [5]
A occurs at [1, 3, 6]

So far, I haven't coded for "does not occur" since "does occur" is already so strange. Thanks in advance

Your 'ideal' output for PEAR is incorrect: 'P' occurs at [0, 2], not [0, 1] — Erwin Bolwidt
– Erwin Bolwidt, Commented Apr 5, 2014 at 3:12
To the downvoter: please read the Help center. Homework or similar things are okay as a question if they indicate what work has been done so far and what the difficulty is. I think the OP has done that here. — Erwin Bolwidt
– Erwin Bolwidt, Commented Apr 5, 2014 at 3:21

Erwin Bolwidt · Accepted Answer · 2014-04-05 03:17:06Z

You have your inner an outer loop mixed up, and you're using the wrong index (i or j) with the wrong array/string at times. It helps to give i and j more descriptive names so you know when to use which. And lastly, you can only print the "occurs" string after you've tried to find all occurrences, otherwise you are printing a whole line for every occurrence, instead of one line for all occurrences of a character.

This fixes your loop:

for (int stringIndex = 0; stringIndex < string.length(); stringIndex++) {
    char ch = Character.toUpperCase(string.charAt(stringIndex));
    List<Integer> letterList = new ArrayList<Integer>();
    for (int anArrayIndex = 0; anArrayIndex < anArray.length; anArrayIndex++) {
        if (anArray[anArrayIndex] == ch) {
            letterList.add(anArrayIndex);
        }
    }
    System.out.println(ch + " occurs at the following index " + letterList);
}

I'll leave it as an exercise for yourself to test whether letterList is empty (hint: look at Javadoc for method isEmpty()) and print a different message to indicate that you didn't find any occurrences.

bgth · Accepted Answer · 2014-04-05 12:57:28Z

int i;
// Loop to find index of inputted character
// List to store the output
List<String> outList = new ArrayList<String> ();
char[] stringArray = string.toCharArray();    
for (char stringArrayChar: stringArray) {
    // StringBuilder to store output for each iteration
    StringBuilder sb = new StringBuilder();
    sb.append(Character.toUpperCase(stringArrayChar) + " occurs at ");

    // positions List
    List<Integer> posList = new ArrayList<Integer>();
    i = 0;
    for (char anArrayChar: anArray) {          
        if (anArrayChar == Character.toUpperCase(stringArrayChar)) {
           posList.add(i);              
        }
        i++;
    }
    // Check if the char is present in the specified array
    if (posList.size() > 0) { 
        sb.append(posList.toString());            
    } else {
        sb.append(" No Place in Array");
    }
    outList.add(sb.toString());
}
// Print the final result
for(String outString: outList ) {
    System.out.println(outString);
}

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