final final commit, I promise

src/Life.java

   String[] lifeArray;
   
   public static void main(String[] args) {
-    Life l = new Life(new String[] {  "*    ",
-                                      "*    ",
-                                      "*    ",
+    Life l = new Life(new String[] {  "     ",
+                                      "     ",
+                                      " *** ",
                                       "     ",
                                       "     " });
     l = (Life) l.nextGeneration();
   public void setAlive(int x, int y) {
     // TODO Auto-generated method stub
     String newString = "";
-    for(int i = 0; i < lifeArray[y].length(); i++) {
-      if(i == x) {
-        newString += '*';
-      } else {
-        newString += lifeArray[y].charAt(i);
-      }
-    }
 
-      lifeArray[y] = newString;
+    newString = lifeArray[y].substring(0, x) + "*" + lifeArray[y].substring(x);
+
+    lifeArray[y] = newString;
 
 
   }
   public void setDead(int x, int y) {
     // TODO Auto-generated method stub
     String newString = "";
-    for(int i = 0; i < lifeArray[y].length(); i++) {
-      if(i == x) {
-        newString += ' ';
-      } else {
-        newString += lifeArray[y].charAt(i);
-      }
-    }
 
-      lifeArray[y] = newString;
+    newString = lifeArray[y].substring(0, x) + " " + lifeArray[y].substring(x);
+
+    lifeArray[y] = newString;
 
   }
 
   @Override
   public ILife nextGeneration() {
     // TODO Auto-generated method stub
-    Life newWorld = new Life();
+    Life newLife = new Life();
     for(int y = 0; y < lifeArray.length; y++) {
       for(int x = 0; x < lifeArray[y].length(); x++) {
-        int counter = countNeighbors(x, y);
-
-        if(isAlive(x, y)) {
-          if (counter > 3 || counter < 2)
-            newWorld.setDead(x, y);
-          if (counter == 3 || counter == 2)
-            newWorld.setAlive(x, y);
-        }
-        if(!isAlive(x, y)) {
-          if (counter == 3) {
-            newWorld.setAlive(x, y);
-          } else {
-            newWorld.setDead(x, y);
-          }
-        }
+        int neighbors = countNeighbors(x, y);
+
+        writeNewGen(neighbors, newLife, x, y);
       }
     }
 
-    return newWorld;
+    return newLife;
+  }
+
+  private void writeNewGen(int neighbors, Life newLife, int x, int y) {
+
+    //if the space is alive...
+    if(isAlive(x, y)) {
+
+      //...and has more than three or less than two neighbors, it dies
+      if (neighbors > 3 || neighbors < 2)
+        newLife.setDead(x, y);
+
+      //...and has 2 to 3 neighbors, it survives
+      if (neighbors == 3 || neighbors == 2)
+        newLife.setAlive(x, y);
+    }
+
+    //if the space is dead...
+    if(!isAlive(x, y)) {
+
+      //and has 3 neighbors, it comes to life
+      if (neighbors == 3) {
+        newLife.setAlive(x, y);
+      } else {
+        //and has anything but 3 neighbors, it stays dead
+        newLife.setDead(x, y);
+      }
+    }
   }
 
   private int countNeighbors(int x, int y) {
 
   private int countSides(int x, int y) {
     int counter = 0;
-    if(x-1 >= 0)
-      if(isAlive(x-1, y))
+
+    //is the space left us within the playing field and alive?
+    if(x-1 >= 0 && isAlive(x-1, y))
         counter++;
-    if(x+1 < lifeArray[y].length())
-      if(isAlive(x+1, y))
+
+    //is the space right us within the playing field and alive?
+    if(x+1 < lifeArray[y].length() && isAlive(x+1, y))
         counter++;
+
       return counter;
   }
 
   private int countBelow(int x, int y) {
     int counter = 0;
+
+    //is the line below us within the playing field?
     if(y+1 < lifeArray.length) {
       for (int i = x-1; i <= x+1; i++) {
-        if (i >= 0 && i < lifeArray[y+1].length())
-          if(isAlive(i, y + 1))
+
+        //are the spaces on our left, middle and right bottom within the playing field alive?
+        if (i >= 0 && i < lifeArray[y+1].length() && isAlive(i, y + 1))
             counter++;
       }
     }
 
   private int countAbove(int x, int y) {
     int counter = 0;
+
+    //is the line above us within the playing field?
     if(y-1 >= 0) {
       for (int i = x-1; i <= x+1; i++) {
-        if (i >= 0 && i < lifeArray[y-1].length())
-          if(isAlive(i, y - 1))
+
+        //are the spaces on our left, middle and right top within the playing field alive?
+        if (i >= 0 && i < lifeArray[y-1].length() && isAlive(i, y - 1))
             counter++;
       }
     }