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up vote 0 down vote favorite

I am having a little trouble with my code. I have a hash map which has data. I want to get that data from the hash table and so far so good everything was working properly until I tried to get the coordinates of a point. I have made a class called "Segments" it contains a string "name" and an array of Doubles (longitude latitude). It is supposed to fill the variables with data from the hash table. In debug mode I saw the elements the longitude and latitude but it doesn't put them into the arrays I have specified and it prints out an error:

"ClassCastException: java.lang.Object[] cannot be cast to java.lang.Double"

Here is my code. 

    public class Segments 
 {
    public String name;
    public double[] latitude;
    public double[] longitude;

    public void Read(HashMap<String,Object> segment)
    {
        this.name = (String) segment.get("name");       

        Object[] coord = (Object[]) segment.get("coordinates");
        try
        {
            for(int i = 0; i < coord.length; i++)
            {

                latitude[i] = (Double)coord[0];
                longitude[i] = (Double)coord[1];            
            }
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }

    }

Can you tell me what am I doing wrong and how to fix my code?

share|improve this question
    
what is the value of coord[0]? –  shayan pourvatan Feb 10 at 12:32
    
the value of coord is received from the hashtable and it contains longitude and latitude (double value). It has 2 elements longitude and latitude –  user3182266 Feb 10 at 12:33
    
what is the code you are using to populate the segment map? –  Surendran Duraisamy Feb 10 at 12:37

3 Answers 3

up vote 2 down vote

I think the main issue is that your coord array doesn't contain coordinates but rather an array of array of coordinates. Therefore the correct way to address this would be:

for(int i = 0; i < coord.length; i++)
{

    latitude[i] = (Double)coord[i][0];
    longitude[i] = (Double)coord[i][1];            
}

Notice the second-level array inside the loop.

EDIT: You may need to add an explicit cast to coord[i]. Try these - one of them might work for you:

latitude[i] = ((Double[])coord[i])[0];
longitude[i] = ((Double[])coord[i])[1];

or

latitude[i] = ((double[])coord[i])[0];
longitude[i] = ((double[])coord[i])[1];

or

latitude[i] = (Double)((Object[])coord[i])[0];
longitude[i] = (Double)((Object[])coord[i])[1];
share|improve this answer
    
Either that, or coord contains some other type of object. –  Paul-Jan Feb 10 at 12:47
    
@Paul-Jan Possibly, although if it's not this, then his whole logic is flawed. He loops over the coord array assigning the first element to lat and the second long - over and over again. But if coord is a two-element array, then what's the point of the loop? Or of the assignment? –  Aleks G Feb 10 at 12:50
    
An error: The type of the expression must be an array type but it resolved to Object –  user3182266 Feb 10 at 12:56
    
@user3182266 You may need to add explicit cast to coord[i]. I updated my answer with some options. –  Aleks G Feb 10 at 13:02
up vote 1 down vote

You are trying to cast a primitive object to Object.

You can try to change your values do Double or cast to double[]

Also this is a very common mistake, remember that all primitives doesn't extend Object in Java

Try this code:

public class Segments 
   {
    public String name;
    public Double[] latitude;
    public Double[] longitude;


public void Read(HashMap<String,Object> segment)
{
    this.name = (String) segment.get("name");       


Double[] coord = (Double[]) segment.get("coordinates");

    try
    {
        for(int i = 0; i < coord.length; i++)
        {

            latitude[i] = coord[0];
            longitude[i] = coord[1];            
        }
    }
    catch(Exception e)
    {
        e.printStackTrace();
    }

  }
share|improve this answer
    
I am sorry I did not understand that can you show me with code? –  user3182266 Feb 10 at 12:35
    
use Double when you declare the variable as in public Double[] latitude; –  silverback Feb 10 at 12:36
    
nope I get the same error –  user3182266 Feb 10 at 12:38
    
Now the for loop is skipped and never reached; –  user3182266 Feb 10 at 12:55
up vote 0 down vote

Guys I found the solution and of course thank you for your help you pointed me to the right way. Sop the solution was that i had to declare the size of the array and the arrays (latitude, longitude) must be "double" not "Double" and so to fill the arrays (latitude, longitude) the code must look like:

public class Segments 
{
public String name;
public double[] latitude;
public double[] longitude;


public void Read(HashMap<String,Object> segment)
{
    this.name = (String) segment.get("name");       

    Object[] coord = (Object[]) segment.get("coordinates");
    //Object[] coord2 = new Object[coord.length]; 
    latitude = new double[coord.length];
    longitude = new double[coord.length];

    try
    {
        for(int i = 0; i < coord.length; i++)
        {   
            latitude[i] = (Double)((Object[])coord[i])[0];
                longitude[i] = (Double)((Object[])coord[i])[1];                     
        }
    }
    catch(Exception e)
    {
        e.printStackTrace();
    }

}

}

share|improve this answer

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