first commit with two updated files

src/main/java/StringManipulation.java

@@ -1,33 +1,154 @@
-public class StringManipulation implements StringManipulationInterface {
+import java.util.ArrayList;
 
+public class StringManipulation implements StringManipulationInterface {
+
+	private String string;
+	private int count;
+
     @Override
     public String getString() {
-        return null;
+        return string;
     }
 
     @Override
     public void setString(String string) {
+    	this.string = string;
     }
 
     @Override
     public int count() {
-        return 0;
+    	// initialize word count to 0
+    	count = 0;
+
+    	// if statement to check if string is null or empty    	
+    	if (string == null || string.length() == 0) {
+    		return count;
+    	}
+
+    	// split the string into a string array, delimiting by one or more spaces
+    	String[] wordArray = this.string.split("\\s+");
+
+    	count = wordArray.length;
+
+    	return count;
     }
 
     @Override
-    public String removeNthCharacter(int n, boolean maintainSpacing) {
-        return null;
+    public String removeNthCharacter(int n, boolean maintainSpacing) {    	
+    	if (n > string.length()) {
+    		throw new IndexOutOfBoundsException();
+    	} else if (n <= 0) {
+    		throw new IllegalArgumentException();
+    	}
+
+    	// initialize an ArrayList of Characters
+    	ArrayList<Character> charArray = new ArrayList<Character>();
+
+    	// iterate through string and insert each Character in the ArrayList
+    	for (int i = 0; i < string.length();i ++) {
+    		charArray.add(string.charAt(i));
+    	}
+
+    	// determine the highest Nth index less than or equal to the length of this.string
+    	int limit = string.length() / n;
+
+    	// initialize an int array to hold all the indexes to replace
+    	int[] indexesToReplace = new int[limit];
+
+    	// assign each Nth index to an element in the int array
+    	for (int i = 1, j = 0; i <= limit; i++, j++) {
+    		indexesToReplace[j] = n * i;
+    	}
+
+    	//System.out.println("indexes to replace:    " + Arrays.toString(indexesToReplace));
+
+    	// iterate through the ArrayList and replace the Character with space or delete
+    	for (int i = indexesToReplace.length - 1; i >= 0; i--) {
+    		int index = indexesToReplace[i] - 1;
+
+    		if (maintainSpacing == true) {
+    			charArray.set(index, ' ');
+    		}
+
+    		if (maintainSpacing == false) {
+    			charArray.remove(index);
+    		}
+    	} 
+
+    	// build the string from the ArrayList and return to main
+    	StringBuilder stringBuilder = new StringBuilder();
+    	for (char c : charArray) {
+    		stringBuilder.append(c);
+    	}
+
+    	return stringBuilder.toString();
     }
 
     @Override
-    public String[] getSubStrings(int startWord, int endWord) {
-        return null;
+    public String[] getSubStrings(int startWord, int endWord){
+    	// exception: If either "startWord" or "endWord" are invalid
+    	if (startWord <= 0 || endWord <= 0 || startWord > endWord) {
+    		throw new IllegalArgumentException();
+    	}
+
+    	// exception: If the string has less than "endWord" words in it
+    	if (count() < endWord) {
+    		throw new IndexOutOfBoundsException();
+    	}
+
+    	// split the words into a String array, delimited by one or more spaces
+    	String[] arr = this.string.split("\\s+");
+
+    	// intialize the return array with size of the number of words to keep
+    	String[] finalArray = new String[endWord - startWord + 1];
+
+    	// iterate through the array of all words, if the index falls inside the
+    	// range passed in, then put that word in the new array
+    	for (int i = 0, j = 0; i <= arr.length; i++) {
+    		if (i >= startWord && i <= endWord) {
+    			finalArray[j] = arr[i - 1];
+    			j++;
+    		}
+    	}
+
+    	return finalArray;
     }
 
     @Override
-    public String restoreString(int[] indices) {
-        return null;
+    public String restoreString(int[] indices){
+    	// exception: if not s.length == indices.length == n
+    	if (string.length() != indices.length) {
+    		throw new IllegalArgumentException();
+    	}
+
+    	// exception: if indices[i] < 0  or  indices[i] > string length
+    	for (int i = 0 ; i < indices.length; i++) {
+    		if (indices[i] < 0 || indices[i] >= string.length()) {
+    			throw new IndexOutOfBoundsException();
+    		}
+    	}
+
+    	// initialize an ArrayList for the final string to be returned
+    	ArrayList<Character> finalWord = new ArrayList<>();
+
+    	// fill the ArrayList with characters from the original string
+    	for (char c : string.toCharArray()) {
+    		finalWord.add(c);
+    	}
+
+    	// iterate through both the indices parameter and the string characters
+    	// to load the final array with shuffled characters
+    	for (int i = 0; i < string.length(); i++) {
+    		finalWord.set(indices[i], string.charAt(i));
+    	}
+
+    	// build the string from the ArrayList and return to main
+    	StringBuilder stringBuilder = new StringBuilder();
+    	for (char c : finalWord) {
+    		stringBuilder.append(c);
+    	}
+
+    	return stringBuilder.toString();
     }
-
-
 }
+