How to avoid null checking in Java?

Question

I use object != null a lot to avoid NullPointerException.

Is there a good alternative to this?

For example I often use:

Answer 1

Probably the best alternative for Java 8 or newer is to use the Optional class.

Optional stringToUse = Optional.of("optional is there");
stringToUse.ifPresent(System.out::println);

This is especially handy for long chains of possible null values. Example:

Optional i = Optional.ofNullable(wsObject.getFoo())
    .map(f -> f.getBar())
    .map(b -> b.getBaz())
    .map(b -> b.getInt());

Example on how to throw exception on null:

Optional optionalCarNull = Optional.ofNullable(someNull);
optionalCarNull.orElseThrow(IllegalStateException::new);

Java 7 introduced the Objects.requireNonNull method which can be handy when something should be checked for non-nullness. Example:

String lowerVal = Objects.requireNonNull(someVar, "input cannot be null or empty").toLowerCase();