Issue with sorting with collection in java

Question

I have a hashmap:

HashMap<String,QuoteBean> map = new HashMap<String,QuoteBean>();

The QuoteBean is a normal bean:

class QuoteBean{
    String symbol;
    BigDecimal price;
    BigDecimal quoteprice;
    //setter and getter methods
}

Then, I get the values of the map which a collection of QuoteBean objects

Collection obs  =map.values(); //getting all the quoteobjects
List list = new ArrayList(obs); //converted to list

Then to sort:

Collection.sort(list, new SymbolComparator());

SymolComparator is:

public class SymbolComparator implements Comparator<QuoteBean>{
    String symbol;
    @Override
    public int compare(QuoteBean o1, QuoteBean o2) {
        String symbol1=o1.getProductId().getSymbol();
        String symbol2=o2.getProductId().getSymbol();
        return symbol1.compareTo(symbol2);
    }    
}

When I execute the code I get an exeception which says cannot convert String to QuoteBean and the exception throws on the first line.

Something tells me this isn't actually the code that's causing the error. — Mark Elliot
– Mark Elliot, Commented Sep 27, 2010 at 23:40
In the compare() method, you do o1.getProductId()... what does getProductId() return? — weiji
– weiji, Commented Sep 27, 2010 at 23:42

I82Much · Accepted Answer · 2010-09-27 23:42:35Z

2

Are you positive you're not creating a list from the keys?

Collection obs  =map.values(); //getting all the quoteobjects
List list = new ArrayList(obs);

Just for fun make sure you can do

List<QuoteBean> beans = new ArrayList<QuoteBean>(map.values());

answered Sep 27, 2010 at 23:42

I82Much

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2 Comments

swati Over a year ago

I am pretty sure i am getting the values only from the map because once i get the list i am iterating through the list and printing the content which prints all the values...

I82Much Over a year ago

Give us the stack trace, and start putting some debugging statements in your comparator function and we'll be able to help a lot more.

Jayaram · Accepted Answer · 2010-09-27 23:59:48Z

2

I think the mistake is with these two statements...

String symbol1=o1.getProductId().getSymbol();
String symbol2=o2.getProductId().getSymbol();

if you want to sort the based on string you could just say o1.symbol to get the string. I still don;t understand what getproductid() is used for.

edited Sep 27, 2010 at 23:59

answered Sep 27, 2010 at 23:46

Jayaram

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Comments

Emil · Accepted Answer · 2010-09-28 05:23:51Z

0

I think instead of

o1.getProductId().getSymbol();

you should do

o1.getSymbol();

since the QuoteBean has the symbol as a property.

class QuoteBean{
    String symbol;
    BigDecimal price;
    BigDecimal quoteprice;
    //setter and getter methods
}

answered Sep 28, 2010 at 5:23

Emil

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