Java “?” Operator for checking null - What is it? (Not Ternary!)

Question

I was reading an article linked from a slashdot story, and came across this little tidbit:

Take the latest version of Java, which tries to make null-poi

Answer 1

It is possible to define util methods which solves this in an almost pretty way with Java 8 lambda.

This is a variation of H-MANs solution but it uses overloaded methods with multiple arguments to handle multiple steps instead of catching NullPointerException.

Even if I think this solution is kind of cool I think I prefer Helder Pereira's seconds one since that doesn't require any util methods.

void example() {
    Entry entry = new Entry();
    // This is the same as H-MANs solution 
    Person person = getNullsafe(entry, e -> e.getPerson());    
    // Get object in several steps
    String givenName = getNullsafe(entry, e -> e.getPerson(), p -> p.getName(), n -> n.getGivenName());
    // Call void methods
    doNullsafe(entry, e -> e.getPerson(), p -> p.getName(), n -> n.nameIt());        
}

/** Return result of call to f1 with o1 if it is non-null, otherwise return null. */
public static  R getNullsafe(T1 o1, Function f1) {
    if (o1 != null) return f1.apply(o1);
    return null; 
}

public static  R getNullsafe(T0 o0, Function f1, Function f2) {
    return getNullsafe(getNullsafe(o0, f1), f2);
}

public static  R getNullsafe(T0 o0, Function f1, Function f2, Function f3) {
    return getNullsafe(getNullsafe(o0, f1, f2), f3);
}


/** Call consumer f1 with o1 if it is non-null, otherwise do nothing. */
public static  void doNullsafe(T1 o1, Consumer f1) {
    if (o1 != null) f1.accept(o1);
}

public static  void doNullsafe(T0 o0, Function f1, Consumer f2) {
    doNullsafe(getNullsafe(o0, f1), f2);
}

public static  void doNullsafe(T0 o0, Function f1, Function f2, Consumer f3) {
    doNullsafe(getNullsafe(o0, f1, f2), f3);
}


class Entry {
    Person getPerson() { return null; }
}

class Person {
    Name getName() { return null; }
}

class Name {
    void nameIt() {}
    String getGivenName() { return null; }
}