added comments, fixed ensureCapacity method

Author: bluecrayon52

MyString.java

@@ -4,7 +4,7 @@
  * CSC230-02 Spring 2016
  */
 
-import java.util.Arrays;
+import java.util.Arrays; // used in equals method 
 
 public class MyString {
 
@@ -21,46 +21,67 @@ public MyString() {
     public MyString(String str) {
         currLength = str.length();
         strChars = new char[currLength];
-        ensureCapacity();
+         
         for (int i = 0; i < currLength; i++) {
             strChars[i] = str.charAt(i);
         }
+        ensureCapacity();
     }
 
  // Copy Constructor 
     public MyString(MyString str) {
         currLength = str.currLength;
         strChars = new char[currLength]; 
-        ensureCapacity(); 
+         
         for (int i = 0; i < currLength; i++) {
             strChars[i] = str.strChars[i];
+            
         }
-       
+       ensureCapacity();  
     }
 
- // Length Method 
+ // Length Method, returns length of string in array, not last array index  
     public int length() {
         return currLength;
     }
 
  // Allocate additional memory for the string 
     private void ensureCapacity() {
 
-        if(this.currLength == this.strChars.length){
-            char[] cap = new char[this.currLength*2];
+            // increase size of array 
+            char[] cap = new char[this.currLength + 1];
+            
+            // pass values to temp array 
+            for(int i = 0; i < currLength; i++){
+                cap[i] = strChars[i]; 
+            }
+            // new instance of strChars
+            strChars = new char[this.currLength + 1];
+            
+            //pass values back 
+            for(int a = 0; a < currLength; a++){
+               strChars[a] = cap[a];        
+            }
+             
         }
 
-    }
+    
 
  // return a string representation of the MyString object 
     public String toString() {
 
-        if(strChars == null){
+        if(strChars == null){ // for empty MyString 
         String stringRep = new String();  
         return stringRep; 
         }
+       
+        // copy array to trim null for printout 
+        char[] copy = new char[currLength]; 
 
-        String stringRep = new String(strChars);
+        for(int i = 0; strChars[i] != '\u0000'; i++){
+               copy[i] = strChars[i];
+            }
+        String stringRep = new String(copy);
         return stringRep;
     }
 
@@ -70,19 +91,23 @@ public String toString() {
 
     public MyString concat(MyString str) {
         int comboLength = str.currLength + currLength;
-        char[] copyArr = new char[comboLength];
-
-        for (int i = 0; i < currLength; i++) {
-            copyArr[i] = strChars[i];
+        
+        // set length of new array 
+        char[] copyArr = new char[comboLength]; 
+        
+        //place first (calling) string into array
+        for (int i = 0; i < currLength; i++) {  
+            copyArr[i] = strChars[i]; 
         }
-
+        // place second (perameter) string into array
         for (int i = currLength, a = 0; i < comboLength; i++, a++) {
-            copyArr[i] = str.strChars[a];
+            copyArr[i] = str.strChars[a];  
         }
-
-        String stringRep = new String(copyArr);
-
-        MyString Concat = new MyString(stringRep);
+        // turn array into string
+        String stringRep = new String(copyArr);  
+        
+        // pass string to MyString constructor
+        MyString Concat = new MyString(stringRep); 
 
         return Concat;
     }
@@ -93,18 +118,24 @@ public MyString concat(MyString str) {
     public MyString concat(String str) {
         int strLength = str.length();
         int comboLength = strLength + currLength;
+        
+        // set length of new array 
         char[] copyArr = new char[comboLength];
-
+        
+        // place first (calling) string into array 
         for (int i = 0; i < currLength; i++) {
             copyArr[i] = strChars[i];
         }
-
+        
+        //place second (peramter) string into array 
         for (int i = currLength, a = 0; i < comboLength; i++, a++) {
             copyArr[i] = str.charAt(a);
         }
-
+        
+        // turn array into string 
         String stringRep = new String(copyArr);
-
+        
+        //pass string to MyString constructor 
         MyString Concat = new MyString(stringRep);
 
         return Concat;
@@ -124,9 +155,12 @@ public boolean equals(MyString str) {
 
     // or an alternative to importing java.util.Array for .equals method 
     public boolean equalTo(MyString str) {
-
+        
+        // check for length equality 
         if (str.currLength != currLength) {
             return false;
+            
+        // traverse arrays for inequalities 
         } else if (str.currLength == currLength) {
             for (int i = 0; i < currLength; i++) {
                 if (strChars[i] != str.strChars[i]) {
@@ -143,36 +177,51 @@ public boolean equalTo(MyString str) {
      pos int if this MyString is alph. after perameter
      */
     public int compareTo(MyString str) {
+        
+        // determine shortest string for inbounds traversal indexing 
         int length_diff = currLength - str.currLength;
         int charDiff = 0;
-
+        
+        // calling object is shorter 
         if (length_diff < 0) {
             for (int i = 0; i < currLength; i++) {
+                
+                // lower case using wrapper class
                 charDiff = Character.toLowerCase(strChars[i])
                         - Character.toLowerCase(str.strChars[i]);
+                
+                //return first difference 
                 if (charDiff < 0 || charDiff > 0) {
                     return charDiff;
                 }
             }
         }
-
+        
+        // perameter is shorter or equality of lengths 
         if (length_diff >= 0) {
             for (int i = 0; i < str.currLength; i++) {
+                
+                // lower case using wrapper class
                 charDiff = Character.toLowerCase(strChars[i])
                         - Character.toLowerCase(str.strChars[i]);
+                
+                // return first difference 
                 if (charDiff < 0 || charDiff > 0) {
                     return charDiff;
                 }
             }
         }
-
+        
+        // return no difference 
         return charDiff;
     }
 
     /*  .get method, takes int, returns char at index location 
      int must be in range! 
      */
     public char get(int index) {
+        
+        // respond to out of bounds indexing
         if (index < 0 || index > currLength - 1) {
             System.out.println("index out of bounds!");
             return '?';
@@ -181,12 +230,19 @@ public char get(int index) {
     }
 // .toUpper method, ruturns MyString that is in all upper case
     public MyString toUpper() {
+        
+        // copy origional to leave it unchanged 
         char[] strChars2 = new char[currLength];
         for (int i = 0; i < currLength; i++) {
+            
+            //upper case using wrapper class
             strChars2[i] = Character.toUpperCase(strChars[i]);
         }
+        
+        // turn array into string 
         String stringRep = new String(strChars2);
-
+        
+        // pass string to MyString constructor 
         MyString Upper = new MyString(stringRep);
 
         return Upper;
@@ -196,12 +252,19 @@ public MyString toUpper() {
 
 // .toLower method, returns MyString that is in all lower case
     public MyString toLower() {
+        
+        // copy origional to leave it unchanged 
         char[] strChars2 = new char[currLength];
         for (int i = 0; i < currLength; i++) {
+            
+            // lower case using wrapper class
             strChars2[i] = Character.toLowerCase(strChars[i]);
         }
+        
+        //turn array into string 
         String stringRep = new String(strChars2);
-
+        
+        // pass string to MyString constructor 
         MyString Lower = new MyString(stringRep);
 
         return Lower;
@@ -214,29 +277,39 @@ public MyString toLower() {
      If parameter is not found in the calling object, method returns -1 
      */
     public int indexOf(MyString str) {
+        
+        // assume no occurance initially 
         int index = -1;
 
+        // if perameter is longer than calling object, no occurance 
         if (str.currLength > currLength) {
 
             return index;
         }
-
+        
+        // traverse calling array until perameter can no longer fits 
         for (int i = 0; i <= currLength - str.currLength; i++) {
-
+            
+           // peramter of length 1 
             if (strChars[i] == str.strChars[0] && str.currLength == 1) {
                 index = i;
                 return index;
             }
-
+            // search for occurance of first letter in perameter string 
             if (strChars[i] == str.strChars[0]) {
+                
+                // check for subsequent equality 
                 for (int a = 1; a < str.currLength; a++) {
                     if (strChars[i + a] == str.strChars[a]) {
+                        
+                        // check for first complete occurance 
                         if(a == str.currLength -1){
                            index = i; 
                            return index;  
                         }
                     } 
 
+                    // subsequent equality failed, back to outer for loop 
                     else {
                         break;
                     }
@@ -253,26 +326,37 @@ public int indexOf(MyString str) {
      If parameter is not found in the calling object, method returns -1   
      */
     public int lastIndexOf(MyString str) {
+        
+        // assume no occurance initially 
         int index = -1;
 
+        // if perameter is longer than calling object, no occurance
         if (str.currLength > currLength) {
 
             return index;
         }
-
+        // traverse calling array until perameter can no longer fits
         for (int i = 0; i <= currLength - str.currLength; i++) {
-
+            
+            // peramter of length 1, set index but keep looking 
             if (strChars[i] == str.strChars[0] && str.currLength == 1) {
                 index = i;
             }
-
+            
+            //search for occurance of first letter in perameter string
             if (strChars[i] == str.strChars[0]) {
+                
+                // check for subsequent equality 
                 for (int a = 1; a < str.currLength; a++) {
                     if (strChars[i + a] == str.strChars[a]) {
+                        
+                       // for first complete occurance, set index, keep looking 
                         if(a == str.currLength -1){
                            index = i;
                         }
-                        
+                      /*potential first occurance failed, index not set 
+                        back to outer for loop
+                        */  
                     } else if (index == -1){
                         break;
                     }
@@ -286,12 +370,16 @@ public int lastIndexOf(MyString str) {
      index. 
      */
     public MyString substring(int start) {
+        
+        // initialize and populate new array 
         char[] sub = new char[currLength - start];  
         for(int n = start, a = 0; n < currLength; n++, a++){ 
             sub[a] = strChars[n]; 
         }
+        // turn array into string 
         String stringRep = new String(sub);
 
+        //pass string to MyString constructor 
         MyString substring = new MyString(stringRep);
 
         return substring;
@@ -302,12 +390,16 @@ public MyString substring(int start) {
     where n is the starting index and m is one past the ending index.  
      */
     public MyString substring(int start, int end) {
+        
+        // initialize and populate array 
         char[] sub = new char[end - start +1];  
         for(int n = start, a = 0; n <= end; n++, a++){ 
             sub[a] = strChars[n]; 
         }
+        // turn array into string 
         String stringRep = new String(sub);
 
+        // pass string to MyString constructor 
         MyString substring = new MyString(stringRep);
 
         return substring;