java.math.BigInteger cannot be cast to java.lang.Long

Question

I've got List<Long> dynamics. And I want to get max result using Collections. This is my code:

List<Long> dynamics=spyPathService.getDynamics();
        Long max=((Long)Collections.max(dynamics)).longValue(); 

This is my getDynamics:

public List<Long> getDynamics() {

        Session session = null;

        session = this.sessionFactory.getCurrentSession();
        Query query = session
                .createSQLQuery("SELECT COUNT(*) FROM SpyPath WHERE DATE(time)>=DATE_SUB(CURDATE(),INTERVAL 6 DAY) GROUP BY DATE(time) ORDER BY time;");

        List<Long> result = query.list();
        return result;

    }

Now I'm getting java.math.BigInteger cannot be cast to java.lang.Long. What's wrong?

Solution 1

Your error might be in this line:

List<Long> result = query.list();

where query.list() is returning a BigInteger List instead of Long list. Try to change it to.

List<BigInteger> result = query.list();

Solution 2

Better option is use SQLQuery#addScalar than casting to Long or BigDecimal.

Here is modified query that returns count column as Long

Query query = session
             .createSQLQuery("SELECT COUNT(*) as count
                             FROM SpyPath 
                             WHERE DATE(time)>=DATE_SUB(CURDATE(),INTERVAL 6 DAY) 
                             GROUP BY DATE(time) 
                             ORDER BY time;")
             .addScalar("count", LongType.INSTANCE);

Then

List<Long> result = query.list(); //No ClassCastException here  

Related link

• Hibernate javadocs
• Scalar queries
• Hibernate.LONG, remember it has been deprecated since Hibernate version 3.6.X
  here is the deprecated document, so you have to use LongType.INSTANCE
• My previous answer

Solution 3

Try to convert the BigInteger to a long like this

Long longNumber= bigIntegerNumber.longValue();

Solution 4

I'm lacking context, but this is working just fine:

List<BigInteger> nums = new ArrayList<BigInteger>();
Long max = Collections.max(nums).longValue(); // from BigInteger to Long...

Solution 5

It's a very old post, but if it benefits anyone, we can do something like this:

Long max=((BigInteger) Collections.max(dynamics)).longValue(); 

View more solutions

Comments

[Brian Roach]

I'd say you're trying to cast a BigInteger to a Long.

[Luiggi Mendoza]

Because a java.math.BigInteger class instance is not an instance of java.lang.Long class.

[Eric Stein]

You're going to need to provide more code if you want more help. Maybe the line the error is pointing to? And what type does getDynamics() return?

[user902383]

you have your answer in your question, i assume this Collections.max(dynamics)) is BigInteger, and you are trying cast it to long, try to cast it to BigInteger, and then use longValue()method

[StormeHawke]

Ok people, he's clearly labeled his dynamics list as a List<Long>. @Tony Check the return type of spyPathService.getDynamics(). Assuming your error is actually coming from these lines of code, I would guess from this code that spyPathService.getDynamics() is actually returning a List that at the very least includes some BigIntegers

[Tony]

I heard that COUNT(*) statement returns Long. Doesn't it?

[mike]

As @StormeHawke said '...is actually returning a List that at the very least includes some BigIntegers'. So you better find out exactly, before you run into the next problem of this kind.

[gavenkoa]

This answer lies on wrong assumption about internal Hibernate wrapper types! The only Aniket Kulkarni answer SQLQuery#addScalar is right!

[gavenkoa]

You are hero! +1, but really +100!

[Bills]

I also type cast the list