Multiple class applet

[lordbob75]

Hey I am still just learning Java programming, and I am working on a program for Warhammer 40K (yeah im a nerd) that will cut out a lot of the dice rolling involved.

Anyways, I am making the menu for now, and I have one class for each menu so far, and I want to link all the classes to run from one master class that runs the applet. I tried to do it all in one class, but it would have been thousands of lines, and many linking problems I just didnt want to deal with. Anyone know how to link the classes that way? My teacher suggested Object references, but i dont know how to use them. Any suggestions?

[Fubarable]

There is no difference on how you'd use multiple classes here with applets as you would with any java project that uses multiple classes. Have you created a class previously that was used by another class? I'm sorry, but I'm not quite sure exactly what your question is.

Best of luck.

[hardwired]

Anyone know how to link the classes that way? My teacher suggested Object references, but i dont know how to use them. Any suggestions?
Yes. There are many ways to put things together. Here's an example to give you an idea:

// <applet code="MultiClass" width="300" height="300"></applet>
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

public class MultiClass extends JApplet {
    // Object references can be declared:
    // ClassType variableName;
    // or declared and instantiated:
    // ClassType reference/variable = new Object();
    // Object on right hand side is created/instantiated
    // with the new operator. A reference to it,
    // saved in a member variable, is what we use to
    // access the objects fields and methods.
    // Use the "view" variable to access fields and call
    // methods in this new instance of the View class.
    View view = new View();
    // Create an instance of the Control class and save
    // a reference to it (the new object) in the member
    // variable "control".
    Control control = new Control(view);

    public void init() {
        System.out.println(getLayout().getClass().getSimpleName());
        add(view);
        add(control.getControlPanel(), "Last");
    }
}

class View extends JPanel {
    Color color = Color.blue;
    Point center = new Point(150,125);
    int side = 100;

    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.setColor(color);
        g.drawRect(center.x-side/2, center.y-side/2, side, side);
    }

    public void setCenterX(int x) {
        center.x = x;
        repaint();
    }

    public void setCenterY(int y) {
        center.y = y;
        repaint();
    }

    public void setColor(Color color) {
        this.color = color;
        repaint();
    }
}

class Control implements ActionListener, ChangeListener {
    // Object reference to the instance of the View class
    // being shown in the applet. You can use this object
    // reference to access fields and call methods in this
    // instance of View.
    View view;
    JSlider xSlider;
    JSlider ySlider;

    public Control(View view) {
        this.view = view;
    }

    public void actionPerformed(ActionEvent e) {
        Color color = ((JButton)e.getSource()).getBackground();
        view.setColor(color);
    }

    public void stateChanged(ChangeEvent e) {
        JSlider slider = (JSlider)e.getSource();
        int value = slider.getValue();
        if(slider == xSlider) {
            view.setCenterX(value);
        }
        if(slider == ySlider) {
            view.setCenterY(value);
        }
    }

    public JPanel getControlPanel() {
        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.insets = new Insets(2,2,2,2);
        gbc.weightx = 1.0;
        gbc.fill = GridBagConstraints.HORIZONTAL;
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        panel.add(getSliderPanel(), gbc);
        panel.add(getButtonPanel(), gbc);
        return panel;
    }

    private JPanel getSliderPanel() {
        Point p = view.center;
        xSlider = getSlider(p.x);
        ySlider = getSlider(p.y);
        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.insets = new Insets(2,2,2,2);
        addComponents("x", xSlider, panel, gbc);
        addComponents("y", ySlider, panel, gbc);
        return panel;
    }

    private JSlider getSlider(int value) {
        JSlider slider = new JSlider(50, 250, value);
        slider.addChangeListener(this);
        return slider;
    }

    private void addComponents(String s, JSlider slider, Container c,
                               GridBagConstraints gbc) {
        gbc.weightx = 0;
        gbc.fill = GridBagConstraints.NONE;
        c.add(new JLabel(s), gbc);
        gbc.weightx = 1.0;
        gbc.fill = GridBagConstraints.HORIZONTAL;
        c.add(slider, gbc);
    }

    private JPanel getButtonPanel() {
        Color[] colors = {
            Color.red, Color.green.darker(), Color.blue, Color.orange
        };
        JPanel panel = new JPanel(new GridLayout(1,0));
        for(int i = 0; i < colors.length; i++) {
            JButton button = new JButton(" ");
            button.setBackground(colors[i]);
            button.addActionListener(this);
            panel.add(button);
        }
        return panel;
    }
}

[dswastik]

Create separate java files for each class and make the classes as public class.

[lordbob75]

Ok, so is the slideshow class supposed to link the classes togetther? I am only a beginning programmer, that confused me a little bit....

[hardwired]

is the slideshow class supposed to link the classes togetther?
The linking of classes is usually done in the class that has the main method and builds/shows the gui (graphical user interface). This is a logical place to assemble/put everything (components) together.
In the example the linking is done in the JApplet, here:

public class MultiClass extends JApplet {
    View view = new View();
    Control control = new Control(view);