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);
}
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Answer 1

To keep the original value of someField (in case null is a valid value), you can use a ternary operator.

String.format("This is %s", (this.someField == null ? "unknown" : this.someField));