multiple Constructors and if Statement

Question

I want to, within my abstract class, define two constructors.

When create a new instance of the class, i want the toString to return something different depending on what was called:

The FireEngine Class

public class FireEngine extends EmergencyVehicle {  

    private String colour;

    public FireEngine(String colour) {
        super (colour);

    }
    public FireEngine() {
        this("red");

    }

    public String toString () {
        if (colour == "red") {
            return "red";
    }   else
        return "no";
    }
}

The EmergencyVehicle class:

public abstract class  EmergencyVehicle extends RoadVehicle {

    public boolean codeBlue = false;

    public EmergencyVehicle(String colour){
        super(colour);
    }

    public boolean isEmergency () {
        if (codeBlue == true) {
            return true;
        } else {
            return false;
        }
    }

    public void setEmergency(boolean newEmergency) {
        codeBlue = newEmergency;
    }

}

This is a homework exercise so I don't want the answer per se, but does the above code make sense?

For example, if I add a new EmergencyVehicle, I want an if statement depending on what colour the vehicle I add is.

Well, not really makes sense, although your intention was probably clear... http://stackoverflow.com/questions/513832/how-do-i-compare-strings-in-java — OneCricketeer, Nov 28 '16 at 11:37
Instead of String maybe you might want to use a predefined Color type? https://docs.oracle.com/javase/7/docs/api/java/awt/Color.html — HRgiger, Nov 28 '16 at 11:40
Your `isEmergency` method could be hugely simplified to `return codeBlue;` — JonK, Nov 28 '16 at 11:44

score 4 · Accepted Answer · 2016-11-28T11:55:17.197

4

1st Remark

Don't call

this("red");

in the default constructor, do

colour = "red";

unless the ~~EmergencyVehicle(String colour)~~ RoadVehicle(String colour) constructor is doing something else.

2nd Remark

Don't compare using

if (colour == "red")

use

if ("red".equals(colour))

3rd Remark

The method

public String toString()

is supposed to return a string representation of the instance. You implementation only returns red or no which is not very informative. Use something like

return("FireEngine(colour=" + colour + ")");

edited Nov 28 '16 at 11:55

answered Nov 28 '16 at 11:37

What is wrong with `this("red")`? Maybe the super call properly does `colour = "red"` – OneCricketeer Nov 28 '16 at 11:38
@cricket_007 Probably not. Note `private String colour;`. – Nov 28 '16 at 11:41
2

But then there would be no need for the `private String colour;` – Grunzwanzling Nov 28 '16 at 11:42
@Grunzwanzling 'then': in which case? I doubt that the OP knows about how to structure a class hierachy. – Nov 28 '16 at 11:42
Right. Your answer is fine, just unclear what the parent class is doing – OneCricketeer Nov 28 '16 at 11:42
I am sorry. It was meant as an answer to @cricket_007. I meant the same thing as you. – Grunzwanzling Nov 28 '16 at 11:43
@Grunzwanzling Thanks for the help! I removed the `Private String Colour` and it worked. I am new to coding, so could you explain what was causing the code not to work properly with setting the String Colour as private – Alex Walton Nov 28 '16 at 12:20

multiple Constructors and if Statement

1 Answers1