No idea what to do for this

Here is the prompt I got-
The code below shows some of the text for a class called City. As you can see, a City has two instance variables, name and population. Write a complete public constructor (including header line) with no parameters, which sets the population to an initial value of -1, and the name to an initial value of "unknown".

Code :

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public class City {
 
  private String name;
  private int population;

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thats all i know haha

I believe what you're being asked to do is something like this:

Code :

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public City(String _name, int _population)
{
population = _population;
name = _name;
}

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And then create a "City":

Code :

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City NewCity = new City("New York", 100);

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See how I use the constructors I created in making a new "City"?
I'm a beginner but I'm pretty sure that's right.

Then what is the actual answer? because all i have so far is

Code :

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public class City {
 
  private String name;
  private int population;

---

so im not sure what follows it

It would be:

Code :

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public class City {
public static void main(String args[]){
  private String name;
  private int population;
  public City(String _name, int _population)
 {
    population = _population;
    name = _name;
 }
City NewCity = new City("New York", 100);
}
}

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Yeah, that didn't work.

I tried substituting "unknown" for "New York" and -1 for 100 because thats what the prompt said but that didnt work either

I figured it out.

Code :

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public City()
{
name = "unknown";
population = -1;
}

---

is what has to be put in

Uhmmmm, that's not a constructor method but sure that will work, I didn't realize you wanted it that simple lol.

That is a constructor. It's what's known as a "default constructor", i.e. it intializes all the values to some pre-determined initial value, in this case -1 and "unknown".

As a second note, if you are going to be providing other constructors that create an initial value (say, a constructor which also sets the city name), I would recommend calling that constructor from the the default constructor. This reduces the amount of code you have to check for problems.

Code Java:

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public City()
{
    // call the other constructor that actually assigns values
    this("unknown", -1);
}
 
public City(String name, int population)
{
    this.name = name;
    this.population = population;
}

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