Calling a method from JFrame from another class

Question

I am currently making a terrain generator, everything works fine in one class but I am going to be expanding my application.

Currently I have a JFrame class which holds everything, generating the terrain, painting the terrain, finding locations etc.

I want to add another class that will generate the terrain but when I create this class I need to access fields from the main JFrame class and when I do I get a stack overflow error - here is my code.

public class Simulator extends Applet
{
//fields

public Simulator()
{
    grid = new int[100][100];
    inhabGrid = new boolean[grid.length][grid.length];
    gridSize = grid.length - 1;
    dist = grid.length;
            TerrainGenerator gen = new TerrainGenerator();
    setSize(dist,dist);
    seedGrid();
    findInhabLocation();
    printGridToConsole();
}

public void paint(Graphics g)   
{
    //panting the grid
}

public void seedGrid()
{
    //seeding

}

public boolean generateTerrain(int x1,int y1, int x2, int y2) 
{

    //terrain generator
}

public boolean mouseUp(Event evt, int x, int y)
{
    seedGrid(); //Create a new map
    findInhabLocation();
    repaint();
    printGridToConsole();
    return true;
}

public boolean keyEvents(Event evt, int x, int y)
{
    seedGrid(); //Create a new map
    findInhabLocation();
    repaint();
    printGridToConsole();
    return true;
}

public void findInhabLocation()
{
    //find best inhabitant location
}

public int locateWater(int x, int y)
{

    //finding closest water
}

public int locateJungle(int x, int y)
{
    //finding closest jungle
}


}
}

That works fine in its own class but when I create a class for example:

public class TerrainGenerator 
{
Simulator sim = new Simulator();
}

I know this has something to do with the constructor and it's something silly I am doing, what would be the best way of splitting up this app into classes, for example terrain generator, inhabitants etc

For example I want to be able to call a method from the 'TerrainGenerator' class and call ie terrainGenerator.generateTerrain

Answer 1

Your TerrainGenerator creates a Simulator object and vice versa, hence you'll end up with infinitely many objects (but at some point the stack is full and a stack overflow exception is thrown instead...)

Instead of creating a new Simulator in your TerrainGenerator , you should pass a reference to your current Simulator (well, actually, that is not a great design either, but I'm not gonna confuse you with the problems of circular references).

Answer 2

更严格的答案是正确的，此外，我认为您可以看看MVC来帮助您组织课程。

Answer 3

Depending which should be the parent, you can pass in the instantiated class to the other, ie;

private final TerrainGenerator gen;  //if you need to save this.
public Simulator(TerrainGenerator terrainGenerator)
{

  this.gen = terrainGenerator;
 ....etc
}


public class TerrainGenerator 
{
Simulator sim = new Simulator(this);
}

or

private final TerrainGenerator gen;  //if you need to save this.
public Simulator()
{

  this.gen = new TerrainGenerator(this);
 ....etc
}

private final Simulator sim; //If you need to save it.
public class TerrainGenerator 
{
  public TerrainGenerator(Simulator simulator) {
    this.sim = simulator;
  }
}