Avoiding Null Checks in Java: Assertions, Exceptions, and the Null Object Pattern

In Java development, null‑pointer checks are ubiquitous, but they often lead to verbose and fragile code.

Two situations should be distinguished: (1) null is a meaningful, valid response, and (2) null indicates an invalid argument that should abort execution.

For the second case, use assertions or throw a NullPointerException to signal the error explicitly.

For the first case, prefer returning empty collections or empty objects instead of null, and consider the Null Object pattern to avoid null checks entirely.

Example of the Null Object pattern:

public class MyParser implements Parser {
    private static Action DO_NOTHING = new Action() {
        public void doSomething() { /* do nothing */ }
    };
    public Action findAction(String userInput) {
        // ...
        if (/* we can't find any actions */) {
            return DO_NOTHING;
        }
    }
}

Using this approach, client code can be simplified from repetitive null checks:

ParserFactory.getParser().findAction(someInput).doSomething();

Additional recommendations include using the safe equals form "bar".equals(foo) , leveraging Java 8/Guava Optional , or throwing an exception instead of returning null.