Question

How should I refactor these code? We're supposed to refactor 5 things.

Here's the conditon:

A minimum of 5 refactoring operations must be performed. The refactoring operations must preserve the program’s functionality. For each refactoring operation, you must insert comments to -Give the refactoring operation a number, -describe what refactoring operation was performed, -give the rationale for your choice of the refactoring operation you have applied, and -put the original code (i.e. before refactoring) inside the comments

public class StringOperations {

   static final int N = 10000;

   public void usingPlus() {
       String s1 = "";
       for (int i = 1; i <= N; i++) {
           s1 = s1 + "*";
       }
   }

   public void usingStringBuffer() {
       StringBuffer sb = new StringBuffer();
       for (int i = 1; i <= N; i++) {
           sb.append("*");
       }
       String s2 = sb.toString();
   }

}

************************************************************************

public class CodeMotion {

    static final int ARLEN = 50000;
    static final double[] x = new double[ARLEN];
    static final double y = (new Random()).nextDouble();

    public void codeInsideLoop() {
        for (int i = 0; i < x.length; i++) {
            x[i] *= Math.PI * Math.cos(y);
        }
    }

    public void codeOutsideLoop() {
        double picosy = Math.PI * Math.cos(y);
        for (int i = 0; i < x.length; i++) {
            x[i] *= picosy;
        }
    }
}

************************************************************************

public class ArrayListvsLinkedList {

    private ArrayList<Integer> al = new ArrayList<Integer>();
    private LinkedList<Integer> ll = new LinkedList<Integer>();
    private static final int N = 100000; // 1000000

    public void arrayListCreation() {
        for (int i = 1; i <= N; i++) {
            al.add(0, new Integer(i));
        }
    }

    public void linkedListCreation() {
        for (int i = 1; i <= N; i++) {
            ll.add(0, new Integer(i));
        }
    }

    public void arrayListAccess() {
        Object o;
        for (int i = 0; i < N; i++) {
            o = al.get(i);
        }
    }

    public void linkedListAccess() {
        Object o;
        for (int i = 0; i < N; i++) {
            o = ll.get(i);
        }
    }
}

************************************************************************

Answer 1

package mar21;

public class StringOperations {

   static final int N = 10000;

   public void usingPlus() {
   String s1 = "";
     
   /*for (int i = 1; i <= N; i++) {
   s1 = s1 + "*";
   }*/
   //Refactoring -1 : instead of starting from 1, I am starting from 0-11 so that it will behave same as original
   for (int i = 0; i < N; i++) {
       //Refactoring -2 : instead of using arithmetic,I am using combined arithmetic
       s1+="*";
   }
   }

   public void usingStringBuffer() {
   StringBuffer sb = new StringBuffer();
/*   for (int i = 1; i <= N; i++) {
   sb.append("*");
   }*/
     
   //Refactoring -3 : instead of starting from 1, I am starting from 0-11 so that it will behave same as original
   for (int i = 0; i < N; i++) {
   sb.append("*");
   }
/*   String s2 = sb.toString();*/  
   //Refactoring -4: creating string objecr using consructor
   String s2 = new String(sb);
   }

   }

   public class CodeMotion {

   static final int ARLEN = 50000;
   static final double[] x = new double[ARLEN];
   static final double y = (new Random()).nextDouble();

   public void codeInsideLoop() {
   for (int i = 0; i < x.length; i++) {
   x[i] *= Math.PI * Math.cos(y);
   }
   }

   public void codeOutsideLoop() {
   double picosy = Math.PI * Math.cos(y);
   for (int i = 0; i < x.length; i++) {
   x[i] *= picosy;
   }
   }
   }

   ************************************************************************

   public class ArrayListvsLinkedList {

   private ArrayList<Integer> al = new ArrayList<Integer>();
   private LinkedList<Integer> ll = new LinkedList<Integer>();
   private static final int N = 100000; // 1000000

   public void arrayListCreation() {
   for (int i = 1; i <= N; i++) {
   al.add(0, new Integer(i));
   }
   }

   public void linkedListCreation() {
   /*for (int i = 1; i <= N; i++) {
   ll.add(0, new Integer(i));
   }*/
  
       //Refactoring -5 : instead of starting from 1, I am starting from 0-11 so that it will behave same as original and adding i+1
       for (int i = 0; i < N; i++) {
   ll.add(0, new Integer(i+1));
   }

   }

   public void arrayListAccess() {
   Object o;
   for (int i = 0; i < N; i++) {
   o = al.get(i);
   }
   }

   public void linkedListAccess() {
   Object o;
   for (int i = 0; i < N; i++) {
   o = ll.get(i);
   }
   }
   }