comparing element in arraylist with an integer value in java

Question

I have loaded the contents of the database in an ArrayList named countList. The contents loaded are of int type. I created countList using the command

ArrayList countList = new ArrayList();

Now, I need to check if each contents of the arraylist is greater than three. I wrote it like

for(int i=0; i< itemset.size(); i++){
    if(countList.get(i) >= 3)
    {

    }
}

When I write it simply, it shows error of bad operand type for binary operator '>='. How to do the task?

Where have you declared supportcount and i? If you have done the declaration correctly, there is not reason why this shouldn't work. — srikanta
– srikanta, Commented Jun 6, 2013 at 1:53
i am sry for errors in the previous post. i have edited the code. itemset is also an arraylist. And i have loaded the two fields product_no and quantity of my database into itemset and countList. — Kris
– Kris, Commented Jun 6, 2013 at 1:57
Print out some items to standard output. See if they are numbers. — yeh
– yeh, Commented Jun 6, 2013 at 2:01

devrobf · Accepted Answer · 2019-05-30 21:45:15Z

4

The >= operator is only defined on number types such as int, double or Integer, Double. Now, countlist may well contain integers (I assume it does), but the way you have written your code, the compiler can't be sure. This is because an ArrayList can store any type of object, including but not necessarily Integer. There are a couple of ways you can remedy this:

a) You can cast the ArrayList item to an Integer, at which point the >= operator will work:

if ( (Integer) countList.get(i) >= 3)

b) You can use generics to tell the compiler that your ArrayList will ONLY store Integers:

ArrayList<Integer> countList = new ArrayList<Integer>();

edited May 30, 2019 at 21:45

answered Jun 6, 2013 at 2:00

devrobf

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Farid Mohd Nor · Accepted Answer · 2013-06-06 01:59:03Z

-1

for(i=0; i< itemset.size(); i++){
   if (itemset.get(i) > 3) {
      // Do whatever you want here
   }
}

answered Jun 6, 2013 at 1:59

Farid Mohd Nor

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1 Comment

Kris Over a year ago

it does not work either. The above post is correct. I used generics as jazzbassrob suggested and it absolutely works

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