How to iterate inside an array of object containing multiple fields?

Question

I have a resultList which fetches result from a JPQL query that queries multiple tables as described :

Query query = em.createQuery("SELECT protein.gid,protein.uniProtAccession,protein.name,protein.ECNumber,ttdtarget.uniProtID,ttdtarget.gid FROM Protein protein,TtdTarget ttdtarget WHERE protein.uniProtAccession = ttdtarget.uniProtID");

List resultList = query.getResultList();

Note: I am restricting the size of resultset to 5 right now, just for debugging. I want to get the values returned inside each object from the resultList, which basically is an array of objects.

So far I have tried iterating upto the objects but can't access the inner values.

for (int i = 0; i < resultList.size(); i++)
{
System.out.println("->"+resultList.get(i));         
}

Output:

->[Ljava.lang.Object;@141ab9e
->[Ljava.lang.Object;@6a15ca
->[Ljava.lang.Object;@bcb654
->[Ljava.lang.Object;@1664b54
->[Ljava.lang.Object;@db953c

And here is the variable's output from debug:

enter image description here

So my question is how to access those values inside the object.

Bozho · Accepted Answer · 2013-07-17 10:07:45Z

3

The result is List<Object[]>, so cast to that. So a list, where each element is an array of values. You must then cast each value to its type (which you know beforehand).

If you simply want to iterate and print:

List<Object[]> resultList = (List<Object[]>) query.getResultList();
for (Object[] array : resultList) {
   for (Object field : array) {
      System.out.println("->"+field); 
   }
}

Alternatively, you can create a new class which has these exact fields, make its constructor accept all of the values, and use it in the query: SELECT new Foo(.....) FROM... There you can use the generic alternative of em.createQuery(..) that returns TypedQuery

edited Jul 17, 2013 at 10:07

answered Jul 17, 2013 at 9:58

Bozho

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2 Comments

JB Nizet Over a year ago

You may not use the generic version of createQuery() for this kind of query. The javadoc says: "The select list of the query must contain only a single item, which must be assignable to the type specified by the resultClass argument."

Bozho Over a year ago

thanks, I'll add it to the "alternative" (I started from that option in mind, and then messed up the order :) )

Flo · Accepted Answer · 2013-07-17 11:01:31Z

3

You don't have a List of Objects, it is a List of Objectarrys

List<Object[]> resultList = (List<Object[])resultList;
for (int i = 0; i < resultList.size(); i++)
{
  System.out.print("protein.gid ->"+resultList.get(i)[0]);
  System.out.println("protein.uniProtAccession ->"+resultList.get(i)[1]);        
}

edited Jul 17, 2013 at 11:01

answered Jul 17, 2013 at 10:09

Flo

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2 Comments

Akina91 Over a year ago

Well this part is giving error : resultList.get(i)[0]), can't access as array.

Flo Over a year ago

Sorry i forgott the cast

dds · Accepted Answer · 2013-07-17 10:00:39Z

2

List<Object[]> resultList = query.getResultList();
for (Object[] objects : resultList)
{
       for (Object object : objects)
       {
          System.out.println(object)
       }
}

answered Jul 17, 2013 at 10:00

dds

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Comments

Naveen Kumar Alone · Accepted Answer · 2014-03-08 12:42:04Z

1

Your result form the query is array of objects.

List resultList = query.getResultList();

for(Object result : resultList) {
  Object[] results = (Object[]) result;
   for(Object res : results) {
     System.out.println(res);
   }
}

Or you can go with Bozho solution and create new direct from query.

edited Mar 8, 2014 at 12:42

Naveen Kumar Alone

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answered Jul 17, 2013 at 10:01

Damian Leszczyński - Vash

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Comments

David SN · Accepted Answer · 2013-07-17 10:39:52Z

0

You can create a new class with the exact fields you need and use a TypedQuery

TypedQuery<CustomClass> query = em.createQuery("" /* Query String */, CustomClass.class);
List<CustomClass> resultList = query.getResultList();
foreach (CustomClass result : resultList){
    // Need to override method toString() in CustomClass
    System.out.println("->" + result);         
}

answered Jul 17, 2013 at 10:39

David SN

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Comments

PunDefeated · Accepted Answer · 2013-07-17 09:58:47Z

-1

I'm tempted to suggest nesting a for loop:

for (int i = 0; i < resultList.size(); i++)
{
  for(int j = 0; j < resutList.get(i).size(); j++){
    System.out.println("->"+resultList.get(i).get(j));
  }         
}

answered Jul 17, 2013 at 9:58

PunDefeated

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1 Comment

JB Nizet Over a year ago

It's a List<Object[]>, not a List<List<Object>>.

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