constructor problem in java

Question

public class StateQueryFilter extends FieldQueryFilter {
   // private static final Log LOG = LogFactory.getLog(RecommendedParser.class.getName());

    public StateQueryFilter() {
        super("state", 5f);
     super("city", 5f);
     super("notdirectory", 5f);
        //LOG.info("Added a state query");
    }

}

And it reports:

Constructor call must be the first statement in a constructor

Is there a way to make it work?

Answer 1

You can only call super once in a constructor, and it must be the first line.

It does not even make sense to call it more than once as you are doing. Calling super does not create a new object; it just lets the superclass initialize its fields. Are you really trying to initialize the same fields more than once? You probably are trying to create three separate objects, but that is not the way to do it.

See also Using the keyword super in the Java tutorials.

Answer 2

Nope. You are trying to construct the object 3 times, the logic is flawed.

Answer 3

From section 8.8.7 of the Java Language Specification:

The first statement of a constructor body may be an explicit invocation of another constructor of the same class or of the direct superclass (§8.8.7.1).

Note "first" statement - you can't have more than one.

Answer 4

I find constructors which call setter ugly.

Another option is to have a constructor which takes the arguments.

public StateQueryFilter() {
    super(/*state*/ 5, /* city */ 5, /*notdirectory*/ 5);
    //LOG.info("Added a state query");
}

However it looks like you should be doing something like

public class StateQueryFilter extends FieldQueryFilter {
    private final String city;
    private final String state;
    private final boolean noDirectory;

    public StateQueryFilter(String city, String state, boolean noDirectory) {
        this.state = state;
        this.city = city;
        this.notDirectory = notDirectory;
    }
}
// later
FieldQueryFilter filter = new StateQueryFiler("Los Angeles", "California", true);

BTW: Don't use float values, they are almost never the best option.