How do you convert string arraylist to double using for loop to calculate?

Question

I'm given the data.txt file and have to calculate the total amount using ArrayList

my data.txt file contains:

32.14,235.1,341.4,134.41,335.3,132.1,34.1

so far I have

public void processFile() throws IOException
{
    File file = new File("SalesData.txt");

    Scanner input = new Scanner(file);
    ArrayList<String> arr = new ArrayList<String>();
    String line = input.nextLine();

    StringTokenizer st = new StringTokenizer(line, ",");

    while (st.hasMoreTokens())
    {
        arr.add(st.nextToken());
    }

    setArrayListElement(arr); //calls setArrayListElement method

}

and here is my setArrayListElement method:

private void setArrayListElement(ArrayList inArray)
{                
    for (int i = 0 ; i < inArray.size() ; i++)
    {
         // need to convert each string into double and sum them up
    }
}

Can I get some help??

Use Double.parseDouble() to convert a String to a double. — Jesper
– Jesper, Commented Nov 14, 2014 at 12:56
Please add parameter to you Arraylist in the parameter private void setArrayListElement(ArrayList<String> inArray) — StackFlowed
– StackFlowed, Commented Nov 14, 2014 at 13:04

Marco Tulio Avila Cerón · Accepted Answer · 2014-11-14 13:10:54Z

2

Never use doubles for monetary calculations (Previous answer is also wrong)
Never refer to a concrete class. The interface in this case is List arr = new ArrayList();

To your specific answer:

BigDecimal summed = BigDecimal.ZERO;

for (int i = 0 ; i < arr.size() ; i++) {
 final String value  = arr.get(i);
 try{
  BigDecimal bd = new BigDecimal(value);
  summed = summed.add(bd);
 } catch(NumberFormatException nfe){
       //TODO: Handle
 }
}

...

edited Nov 14, 2014 at 13:10

answered Nov 14, 2014 at 12:58

Marco Tulio Avila Cerón

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2 Comments

Patricia Shanahan Over a year ago

Any reason for using explicit indexed access rather than for(String value : arr)?

Marco Tulio Avila Cerón Over a year ago

Correct, not needed an index loop in this case.

Jordi Castilla · Accepted Answer · 2014-11-14 12:56:51Z

0

You have to use Double.valueOf():

Double.valueOf(string);

answered Nov 14, 2014 at 12:56

Jordi Castilla

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Comments

SteBra · Accepted Answer · 2014-11-14 12:58:35Z

0

Double value = Double.parseDouble(yourString);

answered Nov 14, 2014 at 12:58

SteBra

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Comments

varoStyle · Accepted Answer · 2014-11-14 13:00:24Z

0

I post you the method to calculate the total amount, dont forget to control exceptions.

    private Double setArrayListElement(ArrayList inArray) throws NumberFormatException
{   
    Double amount=0;    
    for (int i = 0 ; i < inArray.size() ; i++)
    {
       amount= amount+Double.valueOf(inArray.get(i));
    }
    return amount;
}

answered Nov 14, 2014 at 13:00

varoStyle

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