How to iterate through a list and check for null and not null conditions on its elements in java

Question

I have a list saSpComplianceInsuranceList. And it has SaSpComplianceInsurance objects. I have to iterate through each object, and check if the members of object are null or not null. If null nothing should be done. If not null and negative, it should throw an error saying "cannot be negative". These null and not null conditions have to be checked on each member of the object.

For example:

   int index = 0;
   for (SaSpComplianceInsurance saSpComplianceInsurance : saSpComplianceInsuranceList)
   {
       if(saSpComplianceInsurance.getCoverageAmount() != null)
       {
           if(saSpComplianceInsurance.getCoverageAmount() < 0.0)
           {
               fieldErrors.add(new FieldError("pageEntity.saSpComplianceInsuranceList["+index+"].coverageAmount", "genericSpMaintenance.amount.negative", resourceBundle.getString("genericSpMaintenance.InsuranceType." + saSpComplianceInsurance.getInsuranceTypeCode()), resourceBundle.getString("genericSpMaintenance.saSpComplianceInsuranceList.coverageAmount")));
           }
       }

Now I am stuck at this point. When my control reaches first if statement with a null value it is throwing a NullPointerException. If I write this code in try/catch block, what should be written in catch block, so that validation should pass and allow null values?

Maybe you should check that also `saSpComplianceInsurance` is not null — araknoid, Sep 28 '17 at 19:58
Catching unchecked exception is a bad idea. You can go through the answer why it is so https://stackoverflow.com/a/24344547/3213772 — pushpavanthar, Sep 28 '17 at 20:03

Naman · Answer 1 · 2017-09-28T20:06:54.663

You can update the condition from:

if(saSpComplianceInsurance.getCoverageAmount() != null)

to

if(saSpComplianceInsurance !=null) { 
    if(saSpComplianceInsurance.getCoverageAmount() != null)

Also with the current conditions, you can shorten your code then to

if(saSpComplianceInsurance !=null
     && saSpComplianceInsurance.getCoverageAmount() != null
     && saSpComplianceInsurance.getCoverageAmount() < 0.0) {

     fieldErrors.add(new FieldError("pageEntity.saSpComplianceInsuranceList["+index+"].coverageAmount", "genericSpMaintenance.amount.negative", resourceBundle.getString("genericSpMaintenance.InsuranceType." + saSpComplianceInsurance.getInsuranceTypeCode()), resourceBundle.getString("genericSpMaintenance.saSpComplianceInsuranceList.coverageAmount")));
}

which can be further improved as

// util to check all conditions
boolean nullConditionsHandled(SaSpComplianceInsurance saSpComplianceInsurance) {
    returns saSpComplianceInsurance !=null
     && saSpComplianceInsurance.getCoverageAmount() != null
     && saSpComplianceInsurance.getCoverageAmount() < 0.0;
}
....

if(nullConditionsHandled(saSpComplianceInsurance)) {
     fieldErrors.add(new FieldError("pageEntity.saSpComplianceInsuranceList["+index+"].coverageAmount", "genericSpMaintenance.amount.negative", resourceBundle.getString("genericSpMaintenance.InsuranceType." + saSpComplianceInsurance.getInsuranceTypeCode()), resourceBundle.getString("genericSpMaintenance.saSpComplianceInsuranceList.coverageAmount")));
}

5

Username checks out. :-) – Antares42 Sep 28 '17 at 20:00

How to iterate through a list and check for null and not null conditions on its elements in java

1 Answers1