Comparing ArrayList and double array[]

[Gabriel White]

Hi all, I have some code...that doesn't work. I am trying to find the common elements in two arrays. One of them is an array list full of doubles and the second is a double array full of doubles. I am trying to display the value of the element that they have in common and the element number that it is in.

Here is my code:

  public void findCommon(ArrayList array, double[] array2)
    {
        
        ArrayList elementList = new ArrayList();
        System.out.println(array);
        
        for (int i = 0; i < array.size(); i++)
        {
          for (int j = i; j <= array.size(); j++) 
           //System.out.print(array.indexOf(Double.valueOf((String) array.get(i)))); 
           if (Double.valueOf((String) array.get(j)==(String)array2[i]))
           {
             
             array.get(i);
             System.out.println(i);
           }
        }
        
    }   

Thanks in advance.

Gabe.

[Henry Wong]

Couple of really obvious mistakes in your "if" condition...

if (Double.valueOf((String) array.get(j)==(String)array2[i]))

- An double value (array2[i]), which is a primative, can't be casted to a string.

- The "if" condition is expecting a boolean value (or expression) -- not a Double object.

Henry

[Gabriel White]

Hey Henry, thanks for the reply.

I have since changed my code. I did know about the casting the primitive type, but now I can get it to run, but it is all wrong.

Here is my resulting code looking for an indexOf in the Arraylist.

  public void findCommon(ArrayList array, double[] array2)
    {
        
        ArrayList elementList = new ArrayList();
        System.out.println(array);
        
        for (int i = 0; i < array.size(); i++)
        {
          
          for (int j = 0; j <= array.size()-1; j++) 
           //System.out.print(array.indexOf(Double.valueOf((String) array.get(i)))); 
           //System.out.println((Double.valueOf((String)array.get(j))));
           if (array2[i]==array.indexOf(array.get(j)))
           {
             System.out.println(array.get(j));
             System.out.println(i);
           }
        }
        
    }  

[Stephen Foy]

for(int i = 0; i < array.size(); i++) {
    for(int j = i; j <= array.size(); j++) {
           array.get(i); 
           double value = array.get(j);
           if (value == array2[i])
           {
             array.get(i);
             System.out.println(i);
           }
    }
}

[Gabriel White]

Thanks Steve, but still double is required on indicated line in code:

     public void findCommon(ArrayList array, double[] array2)
    {
        for(int i = 0; i < array.size(); i++) 
        {
            for (int j = i; j <= array.size()-1; j++) 
            {
                array.get(i);
                double value = array.get(j);  <---double required
                if (value == array2[i]) 
                {
                    array.get(i);
                    System.out.println(i);
                }
            }
        }
    }   

[Garrett Rowe]

You could turn your array into a List<Double> using Arrays.asList(), and then call the retainAll() method.

[Gabriel White]

I don't think that my compiler will accept Generics. It says something like requires 1.5, current version 1.2.

[Rusty Shackleford]

1.2 is very old(6 or 7 years I think). Is there a reason you are using such an old compiler?
[ April 03, 2006: Message edited by: Rusty Shackleford ]

[Ken Blair]

If the compiler knows it requires 1.5 I doubt it's actually that old. Perhaps that's just the default target for their IDE or whatever they're using? @OP: Is there any reason you have to compile code with a 1.2 compliance?