Make String.format("%s", arg) display null-valued arguments differently from "null"

Question

Consider the custom `toString()` implementation of a bean: ``` @Override public String toString() { String.format("this is %s", this.someField); } ``` This yields `this is null` if `someField` is null. Is there a way to override the default `null` string representation of null-valued arguments to another text, i.e., `?` without calling explicitly `replaceAll(...)` in the `toString` method? Note: The bean inherits from a superclass that could implement `Formattable` (http://docs.oracle.com/javase/7/docs/api/java/util/Formattable.html) but I just don't seem to understand how to make this work. EDIT: The snippet is over-simplified for the sake of example but I'm not looking for ternary operator solutions `someField==null ? "?" : someField` because: - there can be (potentially) a great many fields involved in `toString()` so checking all fields is too cumbersome and not fluent. - other people whom I have little control over (if any) are writing their own subclasses. - if a method is calle…

Accepted Answer

With java 8 you can now use Optional class for this:

```
import static java.util.Optional.ofNullable;
...
String myString = null;
System.out.printf("myString: %s",
    ofNullable(myString).orElse("Not found")
);
```

Make String.format("%s", arg) display null-valued arguments differently from "null"

Solution

Problem