try/catch vs null check in java

Question

Sometimes I face I must write a piece of code like this (usually it have more nested if and more complex structure but for the example is enought)

public voi         


        

Answer 1

A code should never include exception handlers for unchecked exceptions. A null check should always be used for an object reference which has a chance of being null.

Answer 2

If you migrate to Java 8 you can use Optional and Lambdas. First, you need to rewrite your classes to return Optional of each type:

class Object1 {
    private SubObject b;

    Optional<SubObject> getB() {
        return Optional.ofNullable(b);
    }
}

class SubObject {
    private SubObject2 c;

    Optional<SubObject2> getC() {
        return Optional.ofNullable(c);
    }
}

class SubObject2 {
    @Override
    public String toString() {
        return "to be printed";
    }
}

Now, you can chain the calls without the risk of NullPointerExceptions in a concise way:

a.getB()
    .flatMap(SubObject::getC)
    .ifPresent(System.out::println);

See the Oracle's article Tired of Null Pointer Exceptions? Consider Using Java SE 8's Optional! for more information.

Answer 3

The wrongest part of the second version is that when a NPE happens inside the getB(), getC() it will be silently ignored. As already mentioned, exceptions are for exceptional cases.

Answer 4

Using Java 8 optional:

Optional.ofNullable(a)
            .map(Object1::getB)
            .map(SubObject::getC)
            .ifPresent(Object2::print);