Home/ Questions/Q 7537095
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-30T06:45:20+00:00

According to the documentation here (under unique results) and here , A JDO default

  • 0

According to the documentation here (under “unique results”) and here, A JDO “default” query result will return a List, and a “unique” specified query returns null if they are empty.

So am I safe to just use .isEmpty() to check that I got rows for a normal query? Likewise for those times that a query is marked “unique”, should I just use == null?

I tested and a empty result does indeed return a List with .size() of 0. So it seems my only danger of a NullPointerException lies with a “unique” query.

What other precautions should I take (if any)? Do I cover my bases acceptably with just those two types of checks? Pretty much looking for some best practice advice, and any potential gotcha’s. I am pretty novice with both Java and JDO/ORM persistence.

Thanks

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    Right way ? A List is a List and that has a Java contract (API). JDO doesn’t change that. Also the JDO spec (and DN docs) define what form of result comes from a query
    http://www.datanucleus.org/products/accessplatform_3_0/jdo/jdoql_result.html

    • 0