A setter with logic in java

Question

Consider a Message object in Java that stores some text.

public class Message {

    private String text;
    private boolean containsDigit;

    public Message() {
        //constructor
    }

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }

    public boolean isContainsDigit() {
        return containsDigit;
    }

}

This is a persisted object.

I have no problem with data being set in the constructors but the Message's text field can be set after the object is created and when the text is set, the containsDigit field should also be query-able thereafter. The obvious way to do this is in the setter:

public void setText(String text) {
     // presume existence of method to check for digit
     if(text.containsDigit())
         this.containsDigit = true;

     this.text = text;
}

But does this result in any "best practice" alarms bells going off due to having logic within a setter method?

Would anyone suggest an alternative implementation?

EDIT

I should probably add that the containsDigit field is required because the object is persisted so the containsDigit field can be queried subsequently. Also, in an application using the Spring/Hibernate engine, this setter is constantly called when re-reading/writing the object so was wondering about the practicality/efficiency of this also.

Answer 1

Your case is the very reason for using setters and getters. If you weren't allowed to have logic in a setter, then you might as well access the fields directly!

Answer 2

It is probably not the best practice, however sometimes the life is stronger than best practices.

Probably better approach is to remove field containsDigit and move the logic you added to setter into isContainsDigit():

public class Message {
    private final static Pattern d = Pattern.compile("\\d");
    private String text;

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }

    public boolean isContainsDigit() {
        return text == null ? false : d.matcher(text).find();
    }

}