CODEWITHSUNDEEP
javahashmap
Nitumoni Das
Nitumoni Das

Reputation: 21

Arraylist values not coming in a HashMap

I have a HashMap as below:

public static HashMap submitService(HashMap inputMap) throws Exception
    {
        //code....

        ArrayList<String> allIdsList = (ArrayList<String>) inputMap.get("Result_List");
        // System.out.println("Result List: " + allIdsList); prints the arraylist (e.g. [2, 21, 6, 3]

        for(int i=0;i<allIdsList.size();i++)
            {
                System.out.println(" values: " + (String)allIdsList.get(i));
            }
    }

the arraylist is printing in the console(I tried it only to see if the list is not empty). But for (String)allIdsList.get(i) inside the for loop following error message is coming

java.lang.Long cannot be cast to java.lang.String

Would really appreciate someone's help.

Upvotes: 1

Views: 111

Answers (5)

Nagasitaram Thigulla
Nagasitaram Thigulla

Reputation: 188

It looks like allIdsList is of type ArrayList<Long> but you are using ArrayList<String>.

You can change the type of allIdsList to either ArrayList<Long> or remove the generic and use ArrayList.

Upvotes: 0

Mattias Buelens
Mattias Buelens

Reputation: 20159

Where is this inputMap coming from? By the looks of it, its values are not of type ArrayList<String> but something like ArrayList<Object> or even ArrayList<Long>. The problem seems to be somewhere outside your posted snippet.

Since you're working with raw types in this method, the compiler won't complain (although it should warn you about using raw types). However, the VM will throw a ClassCastException where the cast fails - that's what you're seeing.

Try strengthening your signature by only accepting HashMap<String, ArrayList<String>> as inputMap. That way, you can get rid of those awful casts, as you now get compile time type checks. In the best case, this will give the compiler enough information to point out where you're calling this method with an incorrectly typed inputMap. You should then be able to easily fix the error merely by following the compiler's instructions. If that doesn't work, you're probably using raw types in your calls as well and you'll need to dig down the stack trace to fix those.

Upvotes: 0

Aneeq Anwar
Aneeq Anwar

Reputation: 1332

Make sure HashMap is of type HashMap<String,ArrayList<String>>

Upvotes: 1

Steffen Nieuwenhoven
Steffen Nieuwenhoven

Reputation: 525

Try this:

public static HashMap<String,ArrayList<String>> submitService(HashMap<String,ArrayList<String>> inputMap) throws Exception
{
    //code....

    ArrayList<String> allIdsList = inputMap.get("Result_List");
            for(int i=0;i<allIdsList.size();i++)
        {
            System.out.println(" values: " + allIdsList.get(i));
        }
}

Upvotes: 0

ajay.patel
ajay.patel

Reputation: 1967

Replace: public static submitService(HashMap<'String,ArrayList<'String>> inputMap) throws Exception

Looking at the exception, its sure that the parameter passed does not have arraylist of string.Looks like it might be ArrayList<'Object>(with long value present in the list which eventually is casted in String) or Arraylist<'Long>.

Upvotes: 0

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