构造函数无法设置从另一个类获取的数据

Question

Long story I can't figure out how to load the jet data jetid and currentLocation into j . Any help is appreciated. I apologize before hand if I referred to things wrongly. Thank you.

public class Corporation {

    public Jet[] jets = new Jet[14];



    public Corporation()//RUN A CONSTRUCTOR TO CREATE 14 NEW JETS, IN DIFFERENT LOCATIONS
    {
        //create 14 new jets


        for(int i =0; i < jets.length; i++)
        {
            //make a new jet here
            Jet j = new Jet();
            j.jetid = 
        }

    }

}

The second class the one I'm trying to pull jetid and currentLocation from is:

public class Jet {

    public int jetid;
    public Delivery deliveryArray[];
    public String currentLocation; //where it's currently sitting 

    public Jet()
    {
        int random = (int)(Math.random()*10000);

        this.jetid = random;
        this.currentLocation = setCurrentLocation();
        System.out.println("NEW JET IS ONLINE WITH JET ID: " + this.jetid + " AT LOCATION " + this.currentLocation);

    }

    private String setCurrentLocation() 
    {
        //set up a random # that determines which city the plane is based in
        double random = (Math.random());
        String location = " ";

        if(random < .1 && random > 0)
            location = "PHX";

        else if(random > .1 && random < .2)
            location = "SAN";

        else if(random > .2 && random <.3)
            location = "LAX";

        else if(random > .3 && random < .4)
            location = "POR";

        else if(random > .4 && random < .5)
            location = "SEA";

        else if(random > .5 && random <.6)
            location = "SAF";
        else
            location = "DAL";


        return location;
    }

}

Answer 1

Thanks everyone for the input. Other problems aside I settled on this code shortly after posting this question:

Jet j = new Jet();
jets[i]=j;

And from there I've been able to figure out all other issues. Thanks again everyone for your input

Answer 2

Not sure what error you are getting, I assume, your constructor:

public Corporation()//RUN A CONSTRUCTOR TO CREATE 14 NEW JETS, IN DIFFERENT LOCATIONS
{
    //create 14 new jets


    for(int i =0; i < jets.length; i++)
    {
        //make a new jet here
        Jet j = new Jet();
        j.jetid = 
    }

}

Should be the following, if you declared a local j[] in your Corporation class

public Corporation()//RUN A CONSTRUCTOR TO CREATE 14 NEW JETS, IN DIFFERENT LOCATIONS
{
    //create 14 new jets


    for(int i =0; i < jets.length; i++)
    {
        //make a new jet here
        Jet j[i] = new Jet();
        //j.jetid = no need to set this
    }

}

The other thing wrong is the j.jetid = . But you do not need to set it, as it is already set in the Jet constructor to this.jetid = random; . Happens every time you instantiate a new Jet in Jet j[i] = new Jet();

Answer 3

The code appears to create 14 jets, all of which initialise their own data (eg they already have jetId and current location). The data's already there, the Corporation doesn't need to set it.

If you're saying you want the corp to create it, then create a new constructor, Jet(int jetId, String currentLocation) and you can pass the data in.

Answer 4

The corporation object will have an array with 14 references to the Jet object.

public class Corporation {

  private Jet[] jets = new Jet[14];

  // Constructor
  // RUN A CONSTRUCTOR TO CREATE 14 NEW JETS, IN DIFFERENT LOCATIONS
  public Corporation() { 

    //create 14 new jets
    for (int i =0; i < jets.length; i++)
    {
        //make a new jet here
        Jet j = new Jet();
        //save the reference to array
        jets[i] = j;
        // more Jet intialization
        j.id = ...
    }
  }

  // accessor
  public Jet [] getJets() {
    ...
  }

} 

Answer 5

You probably want to pass things in through the constructor:

public Jet(int jetid, String currentLocation)
{
    this.jetid = jetid;
    this.currentLocation = currentLocation;
}

Now you can write the following in your corporation class:

    for(int i =0; i < jets.length; i++)
    {
        //make a new jet here
        int randomId = (int)(Math.random()*10000);
        String randomLocation = randomLocation();
        jets[i] = new Jet(randomId, randomLocation);
    }

That randomLocation is just your old setCurrentLocation method, from your Jet class. You should rename it and move it into your Corporation class, since Corporation is now responsible for making up random locations. Or you could rename it and leave it in Jet, and make it public static, and you could implement it in just 2 lines:

public static String randomLocation() {
    // "DAL" is twice as likely as the others:
    String[] array = {"ABC", "DEF", "DAL", "DAL"};
    return array[new Random().nextInt(array.length)];
}

and then invoke it as follows:

String randomLocation = Jet.randomLocation();

Answer 6

您需要将变量传递给jet类的构造函数！

Jet jet = new Jet(string _jetID, string _currentLocation)

Answer 7

If i have understood your question correctly, you want to set jetid and currentLocation , than you need to change your Jet constructor like the following:

public Jet(int jetid, String currentLocation)
{ 
this.jetid = jetid;
this.currentLocation = currentLocation;
}