java.lang.UnsupportedOperationException but no Arrays.asList()

Question

Getting the below exception which usually comes when we assign a list from a array using Arrays.asList() but i could not see any usage of Arrays in the code where it is being thrown. Moreover the list is initialized using new ArrayList();

    protected List getUnmapParam(PPlan pPlan){
        List unmappedParams = super.getUnmapParam(pPlan, ord);
            PricePlanExt apPP = null;

            if (pricePlan.getapID() != null) {
              apPP = getCurrentlyItem(pPlan.getID(), errorCodeH);
            }
            if (apPP != null) {
              List billParams = apPP.getBillParams();
              for (BillParam billParam : billParams) {
                if (billParam.getnameVal().equals("SD")) {
                  BillUnmapParamType unmappedParamType = getUnMappedType();
                  Attribute attr = mapSimpleParameter(unmappedParamType, apPP, billParam);
                  unmappedParams.add(attr);//Here it is being thrown
                }
              }
            }
            return unmappedParams;
          }

//Super method
protected List getUnmapParameters(Plan pPlan, Ord ord){
    return Collections.EMPTY_LIST;
  }

The stacktrace:

java.lang.UnsupportedOperationException at    
 java.util.AbstractList.add(AbstractList.java:148) at 
 java.util.AbstractList.add(AbstractList.java:108) at 
 java.som.impl.oshooks.BillingImpl.getUnmapParam(BillingImpl.java:121)

java.lang.UnsupportedOperationException at java.util.AbstractList.add(AbstractList.java:148) at java.util.AbstractList.add(AbstractList.java:108) at java.som.impl.oshooks.BillingImpl.getUnmapParam(BillingImpl.java:121) — Sachin
– Sachin, Commented May 15, 2015 at 15:21
add the stacktrace to question not in comments use edit option — singhakash
– singhakash, Commented May 15, 2015 at 15:23
Besides the actual problem: You should not put any of your classes in a package starting with java or javax. See the documentation about naming a package. — siegi
– siegi, Commented May 15, 2015 at 15:48

Community · Accepted Answer · 2017-05-23 11:51:00Z

2

I guess you have at least one of these problems:

Import the wrong ArrayList: No add(…) method of java.util.ArrayList throws a UnsupportedOperationException. Looking at your stack trace indicates that the ArrayList you are using does not even override AbstractList<E>.add(E) (java.util.ArrayList does).
You are running an older version of your code: The line marked by your command (return unmappedParams;) would never throw a UnsupportedOperationException.
You are using a strange JRE version. If the problem is not solved by the first two suggestions, please add the exact version of your JRE (by running java -version).

After the questions edit: Now it is clear, the answer about the list being immutable is correct: You try to add something to a list returned by Collections.EMPTY_LIST. According to the Javadoc this list is immutable.

edited May 23, 2017 at 11:51

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answered May 15, 2015 at 15:34

siegi

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6 Comments

Sachin Over a year ago

java version is 1.7.52 import java.util.ArrayList; import java.util.List;

siegi Over a year ago

@Sachin: What about my second guess? To be sure remove all .class files and rebuild your whole project. Then please also update your comment "Here it is being thrown".

Sachin Over a year ago

I think i got it, i have actually edited the code above. There is a call to super which returns a Collections.EMPTY_LIST and when the overridden method is called, it tries to add to this list causing the UnsupportedException.

siegi Over a year ago

@Sachin: Just saw your update. I also added the explanation to my answer. I still don't believe the exception is thrown in the line you indicate though. ;-)

Sachin Over a year ago

Forgot to correct the exception line. Corrected it :-)

|

Community · Accepted Answer · 2017-05-23 12:14:19Z

2

Your problem is because of Collections.EMPTY_LIST

In general, when seeing that UnsupportedOperationException is being thrown by add, etc. it's typically an indication that some code is trying to modify a non-resizable or unmodifiable collection.

For example, Collections.EMPTY_LIST or Collections.SINGLETON_LIST (which return unmodifiable collections) may be used as optimizations but accidentally be passed into methods that try to modify them.

See UnsupportedOperationException at java.util.AbstractList.add for a more detailed answer

edited May 23, 2017 at 12:14

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answered May 15, 2015 at 17:12

Jihed Amine

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Comments

Kitesurfer · Accepted Answer · 2015-05-15 15:25:14Z

1

I think the root for this kind of Exception could be that the List is Immutable

See the java doc for this

answered May 15, 2015 at 15:25

Kitesurfer

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