How to read the value of a private field from a different class in Java?

Question

I have a poorly designed class in a 3rd-party JAR and I need to access one of its private fields. For example, why should I need to choose priv

Answer 1

Try to go around the problem for the case, the calass of which you want to set/get data is one of your own classes.

Just create a public setter(Field f, Object value) and public Object getter(Field f) for that. You can even do some securoty check on your own inside theses member functions. E.g. for the setter:

class myClassName {
    private String aString;

    public set(Field field, Object value) {
        // (A) do some checkings here  for security

        // (B) set the value
        field.set(this, value);
    }
}

Of course, now you have to find out the java.lang.reflect.Field for sString prior to setting of field value.

I do use this technique in a generic ResultSet-to-and-from-model-mapper.