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Java

Posted by Destiny Robbins
Destiny Robbins
549 Points

Error with summing elements in ArrayList.

Here is my code:

import java.io.*;
import java.math.*;
import java.text.*;
import java.util.*;
import java.util.regex.*;


class Fibonacci
{
    long f1=0;
    long f2=1;
    long f3=0;
    int start, end;
    static ArrayList<Integer> evenFibArrList = new ArrayList<Integer>();
    static int evenFibSum = 0;

    void get() throws IOException
    {
        BufferedReader Br = new BufferedReader(new InputStreamReader(System.in));

        System.out.print("\nEnter the start limit: ");
        start = Integer.parseInt(Br.readLine());

        System.out.print("\nEnter the end limit: ");
        end = Integer.parseInt(Br.readLine());

        System.out.println("\nFibonacci numbers between " + start + " and " + end + " are:" );
    }

    void display()
    {  
        for (int i = start; i < end; i++)
        {       
            if (f3 <= end)
            {  
                if (f3 >=start)
                {
                    System.out.println(f3);

                    if (f3 % 2 == 0)
                    {
                        evenFibArrList.add(new Integer(f3));

                        for(int s = 0; s < evenFibArrList.size(); s++)
                        {
                            //evenFibSum += evenFibArrList.get(s);
                        }
                    }
                }
                f1 = f2;
                f2 = f3;
                f3 = f1 + f2;  
            }
        }
    }

    public static void main(String args[]) throws IOException
    {
        Fibonacci fib = new Fibonacci();
        fib.get();
        fib.display();
        System.out.println(evenFibArrList);
        System.out.println(evenFibSum);
    }
}

I am trying to add the elements of an array list together and print the sum. Here is the error:

Fibonacci.java:42: error: no suitable constructor found for Integer(long)
evenFibArrList.add(new Integer(f3));
^
constructor Integer.Integer(int) is not applicable
(argument mismatch; possible lossy conversion from long to int)
constructor Integer.Integer(String) is not applicable
(argument mismatch; long cannot be converted to String)
1 error

1 Answer

Lukas Dahlberg
Lukas Dahlberg
53,736 Points
Lukas Dahlberg
Lukas Dahlberg
53,736 Points

You've declared f1, f2, and f3 as longs. A long is a 64 bit signed integer (in other words, it can have a +/-) whereas an integer is only 32 bits. So a long will not fit inside an integer while an integer will fit inside a long.

So, when you try to add long to Integer (using autoboxing, incidentally), the compiler throws a fit because you didn't cast long to int, explicitly telling the compiler to do what it can to get an long inside an int, even if the program has to throw away extra bits which, as you might tell, is a bad idea. Instead, you should use List<Long> if you want to keep f1, f2, f3 as long or you should change f1, f2, f3 to int.