Question

This is my class Debugger. Can anyone try and run it and see whens wrong? Ive spent hours on it already. 🙁

public class Debugger {

private String codeToDebug = "";

public Debugger(String code) {
    codeToDebug = code;
}

/**
 * This method itterates over a css file and adds all the properties to an arraylist
 */
public void searchDuplicates() {
    boolean isInside = false;
    ArrayList<String> methodStorage = new ArrayList();
    int stored = 0;
    String[] codeArray = codeToDebug.split("");

    try {
        int i = 0;
        while(i<codeArray.length) {
            if(codeArray[i].equals("}")) {
                isInside = false;
            }
            if(isInside && !codeArray[i].equals(" ")) {
                boolean methodFound = false;
                String method = "";
                int c = i;
                while(!methodFound) {
                    method += codeArray[c];
                    if(codeArray[c+1].equals(":")) {
                        methodFound = true;
                    } else {
                        c++;
                    }
                }
                methodStorage.add(stored, method);

                System.out.println(methodStorage.get(stored));
                stored++;

                boolean stillInside = true;
                int skip = i;
                while(stillInside) {
                    if(codeArray[skip].equals(";")) {
                        stillInside = false;
                    } else {
                        skip++;
                    }
                }
                i = skip;
            }
            if(codeArray[i].equals("{")) {
                isInside = true;
            }
            i++;
        }
    } catch(ArrayIndexOutOfBoundsException ar) {
        System.out.println("------- array out of bounds exception -------");
    }
}

/**
 * Takes in String and outputs the number of characters it contains
 * @param input
 * @return Number of characters
 */
public static int countString(String input) {
    String[] words = input.split("");
    int counter = -1;
    for(int i = 0; i<words.length; i++){
        counter++;
    }
    return counter;
}

public static void main(String[] args) {
    Debugger h = new Debugger("body {margin:;\n}");
    h.searchDuplicates();
}

}

Answer 1

Any place where an element of an array is being obtained without a bounds check after the index is manipulated is an candidate for an ArrayIndexOutOfBoundsException.

In the above code, there are at least two instances where the index is being manipulated without being subject to a bounds check.

1. The while loop checking the !methodFound condition
2. The while loop checking the stillInside condition

In those two cases, the index is being manipulated by incrementing or adding a value to the index, but there are no bound checks before an element is being obtained from the String[], therefore there is no guarantee that the index being specified is not outside the bounds of the array.