CODEWITHSUNDEEP
javastringparsing
JavaCoder
JavaCoder

Reputation: 49

Java: Cannot convert from String to int

What is wrong with this code? It says cannot convert from String to int, but I have already converted it.

public static void main(String[] args) {

    String x = JOptionPane.showInputDialog(null, "Hur många värden haver du?");

    int i = Integer.parseInt(x);

    for (int y = 0; i >= y; y++) {
        String z = JOptionPane.showInputDialog(null, "Skriv in värdet");
        int sum = Integer.parseInt(z);
        sum = (sum + z);
    }
}

Upvotes: 0

Views: 234

Answers (4)

R. Suntjens
R. Suntjens

Reputation: 121

int sum = 0;
for (int y = 0; i >= y; y++) {
    try{
         String z = JOptionPane.showInputDialog(null, "Skriv in värdet");
         sum = (sum + Integer.parseInt(z));
    } catch (Exception e){
         System.out.println("This was not an Integer: " + z);
    }
}

The exception will prevent your program from crashing, but it will not screw up your 'sum'. So you can put an other value again, and go on...

Upvotes: 0

kai
kai

Reputation: 6887

No you have converted z to int and store the result in sum so sum is the int value of z but z is still a variable of type String. What you are trying to do here is the same as multiplying sum by two.

But i assum you want to sum all input values, so you can do sum = (sum + Integer.parseInt(z)); and put the declaration of sum outside the loop, otherwise you initialize it on every iteration. Another bug is that if you input x it will iterate x + 1 times because of i >= y. Fixed version below.

    String x = JOptionPane.showInputDialog(null, "Hur många värden haver du?");

    int i = Integer.parseInt(x);
    int sum = 0;
    for (int y = 0; i > y; y++) 
    {
        String z = JOptionPane.showInputDialog(null, "Skriv in värdet");
        sum = (sum + Integer.parseInt(z));
    }
    System.out.println(sum);

Input: 3 (number of iterations)
Input: 7
Input: 5
Input: 6
Output: 18

Upvotes: 4

Kristoffer
Kristoffer

Reputation: 430

Java don't do automatic conversion between types. So you can't add Strings with numbers and expect it to do math.

What Java does do it auto boxing of primitive types to objects. And it will automatically attempt to call toString() on objects if you use it in a String concatenation.

So as Reimeus wrote. You need to convert the String to a number before you start using it in math

Upvotes: 1

Rustam
Rustam

Reputation: 6515

Cannot convert from String to int

  sum=(sum+z) // int+string // this was the problem

change your z to int as:

    int iz= Integer.parseInt(z);
    sum = (sum + iz);

Upvotes: 0

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