CODEWITHSUNDEEP
javaarraysarraylist
Tapani Yrjölä
Tapani Yrjölä

Reputation: 168

Java convert ArrayList to int array

I want to convert my arraylist to a double array[]. Why can't I cast with this method, what is wrong?

public static void convert(ArrayList list, double array[]) {



    array = new double [list.size()];

    for (int x = 0; x < list.size(); x++) {

        array[x]=(double) list.get(x);

    }

}

I get this error message

String cannot be cast to java.lang.Double

I have this peace of code that does not work if I change fropm raw type ArrayList to Double, maybe suggestions to change this code?

getTest().addAll(Arrays.asList(line.split(",")));

Upvotes: 2

Views: 965

Answers (5)

Masud Parves Bhuiyan
Masud Parves Bhuiyan

Reputation: 224

Use this code: 

public static void convert(ArrayList list, double array[]) {

    array = new double [list.size()];

    for (int x = 0; x < list.size(); x++) 
    {
        Object value = list.get(x);
        if(value instanceof String)
        {
            array[x]=Double.parseDouble(value.toString());
        }
        else if(value instanceof Double)
        {
             array[x]=(double) list.get(x);
        }
        else if(value instanceof Integer)
        {
             array[x]=(int) list.get(x);
        }

    }    
}

Upvotes: 0

Tapani Yrj&#246;l&#228;
Tapani Yrj&#246;l&#228;

Reputation: 168

Ive got the idea. I just convert my ArrayList to ArrayList Then your code examples will work same as mine...

Upvotes: 0

Razib
Razib

Reputation: 11153

You can not apply casting on String to make it double like this - 

array[x]=(double) list.get(x);

Your list is an ArrayList of Stirng. So you have to convert the each String item from the list to double like this - 

public static void convert(ArrayList list, double array[]) {

    array = new double [list.size()];

    for (int x = 0; x < list.size(); x++) {

       array[x]=Double.parseDouble((String)list.get(x));

    }
}

Upvotes: 0

Safwan Hijazi
Safwan Hijazi

Reputation: 2089

use this:

array[x]=Double.parseDouble(list.get(x));

Upvotes: 2

mefi
mefi

Reputation: 1263

Exception message says it - your ArrayList contains String values. You should use generics as ArrayList<String> to prevent this runtime failures

Upvotes: 1

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