ArrayList. ArrayList to int and double

Question

I have the problem that I can't take a number from the arraylist and make it into a int or double which I have to do to cacluate the BMI using weight and height. Please have a look!
The assignment is to put in guests' weight, length, and name and sort the ones with a bad length to height ratio out. In the main I create an array with a couple of guests and when I run it says:

"Exception in thread "main" java.lang.NumberFormatException: For input string "name"

and

java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:492)
at java.lang.Integer.parseInt(Integer.java:527)
at Diet.putOnDiet(Diet.java:12)
at TestDiet.main(TestDiet.java:7)

The Diet class is as follows:

public class Diet{

    public static ArrayList<Guest> putOnDiet(ArrayList <Guest> list){
        ArrayList<Guest> namn = new ArrayList<Guest>();
        ArrayList<Guest> hej = new ArrayList<Guest>();
        for(int i = 0; i<=list.size()/3; i = i+3){

            int langd = Integer.parseInt(list.get(i+1).toString()); //I dont know how to make this work
            double vikt = Double.parseDouble(list.get(i).toString());
            String name = list.get(i+2).toString();

            if ((vikt) > 1.08*(0.9*(langd -100))){
                namn.add(new Guest(vikt, langd, name));
            }
        }

        return namn;
    }
}

And the Guest class:

public class Guest { 

   private double weight; private double length; private String name; 

   public Guest(double weight, double length, String name){ 
      this.name = name; this.weight = weight; this.length = length; // Maybe the problem is here. How do you modify the class to make it work?
   } 
   public String getName() {
      return name; 
   } 
   public double getWeight() 
   { 
      return weight; 
   } 
   public double getLength() { 
      return length; 
   } 
   public void setName(String name) { 
      this.name = name; 
   } 
   public void setWeight(double weight) { 
      this.weight = weight; 
   } 
   public void setLength(double length) 
   { this.length = length; 
   } 
   public boolean isSlim() { 
      if (weight >= 1.08 * 0.9 * (length - 100)) { 
         return false; 
      }
      else 
         return true; 
   }
   public String toString() { 
      return name + "\n" + weight + "\n" + length; 
   } 
}

Well, your toString method isn't returning an int in the form of a string - it's returning a string which can't be parsed into an int. Also, none of those values are ints, so you'll likely need to use Double.parseDouble(). The real issue is that you're trying to convert something like test\n40.2\n16.1 into an int. How is the computer supposed to do that? What is the end result you're looking for with int langd? — WOUNDEDStevenJones
– WOUNDEDStevenJones, Commented Feb 19, 2014 at 16:22

Aamir Abro · Accepted Answer · 2014-02-19 16:36:45Z

2

Are you sure that the you are parsing an integer?

Well number parsing exception is thrown when it can't parse the number. When the string is not a number like "somthing#$%^&". So try replacing this line

int langd = Integer.parseInt(list.get(i+1).toString());

with this

try {
       int langd = Integer.parseInt(list.get(i+1).toString());
} catch (NumberFormatException e) {
       System.out.println(list.get(i+1).toString() +" : This is not a number");
       System.out.println(e.getMessage());
}

EDIT After reading WOUNDEDStevenJones answer I also think you should not be even using toString() or parsing methods. See WOUNDEDStevenJones answer for more details.

edited Feb 19, 2014 at 16:36

answered Feb 19, 2014 at 16:25

Aamir Abro

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Comments

WOUNDEDStevenJones · Accepted Answer · 2014-02-19 20:09:51Z

1

It looks like you'll want to change it to

for (int i=0; i<list.size(); i++) {
    double langd = list.get(i).getLength();
    double vikt = list.get(i).getWeight();
    String name = list.get(i).getName();
}

and kind of ignore your getString() method for this purpose

Note: I'm not sure what you're trying to do with your different indexes, but they'll probably all be .get(i)

edited Feb 19, 2014 at 20:09

answered Feb 19, 2014 at 16:28

WOUNDEDStevenJones

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2 Comments

user3257340 Over a year ago

I used this method and it compiles except when i run the main i get "Exception in thread "main" java.lang.NoSuchMethodError: Guest.<init>(DDLjava/lang/String;)V"

user3257340 Over a year ago

No wait, I made som tweeks it works perfectly now! Thanks alot! <3

tempusfugit · Accepted Answer · 2014-02-19 16:34:49Z

0

The method list.get(i) will return an object of type Guest. Guest has methods, getWeight() and getLength().

list.get(i).getWeight()

This would actually give you a double value in return. And,

Integer.parseInt(list.get(i).getWeight().toString())

This should be able to parse.

Hope this helps.

_san

answered Feb 19, 2014 at 16:34

tempusfugit

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