静态到非静态方法

Question

I am trying to move from a static main() to a non static method called paintComponent(), but the problem I am having is I can not move from Static to Non static in the way which I have. The class is a follows, where hunter and hunted are external classes:

import javax.swing.JFrame;
import java.awt.Graphics;

public class Main extends JFrame{       //Public class: Available for all other classes to refer to

    private static final long serialVersionUID = -4511248732627763442L;

    public static void main(String[] args){     

        frame();
        repaint();
        move();         //Passes to the method move() in the class Main()

    }

    public static JFrame frame(){
        JFrame frame = new JFrame("Hunter VS Hunted");          //Sets the window title
        frame.setExtendedState(JFrame.MAXIMIZED_BOTH);          //Sets the size of the window
        frame.setVisible(true);                                 //Says to display the window
        frame.setResizable(false);                              //Sets it so the screen cannot be adjusted
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);   //Closes the window when the x is pushed        

        System.out.println("Frame works.");  
        return frame;
    }

    public void paintComponent(Graphics g){

        super.paintComponents(g);   //Assigns a graphics value to g, so that it can be passed to other methods                          
        Hunted.paint(g);
        Hunter.paint(g);

        System.out.println("Main.paintComponent works.");

    }

    public static void move(){

        Hunter.move();          //Passes to move() in the Hunter class
        Hunted.move();          //Passes to move() in the Hunter class

    }
}

Bear in mind I am a beginner, so please try to keep it simple!

Answer 1

You need to call repaint and paintComponents using an object.

JFrame frame = frame();
frame.repaint();
move();

Every non-static method needs to be called from an object. Static methods belongs to the class, so you can call them without an object.

repaint and paintComponents belongs to the JFrame object. They are not static and so they need to be called using an object (repaint will call paintComponents). Your 'frame()' method will return a JFrame object. So you can call the repaint() method using the JFrame object that is returned from the 'frame()' method.

Having said that, I'm not sure what you are trying to accomplish in your code, and even if my explanation will resolve a Compilation-Error, without further elaboration, it might not accomplish what you are trying to achieve.

Answer 2

you have got some messed up code! but let me clean it up a bit, make it more presentable. However it is up to you to get it to work now. I have created another class for your jframe and adjusted your extra / repetitive code in the constractor.

btw i know nothing about haunted and haunter.

    import java.awt.Container;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class Main {

public static void main(String[] args){     
    myFrame x = new myFrame("Hunter VS Hunted");
    x.ui(x.getContentPane());

}


}

class myFrame extends JFrame {

    public myFrame(String name){
        // constractor
        super(name); //Sets the window title
        setExtendedState(JFrame.MAXIMIZED_BOTH);          //Sets the size of the window
        setVisible(true);                                 //Says to display the window
        setResizable(false);                              //Sets it so the screen cannot be adjusted
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);   //Closes the window when the x is pushed        
    }

    public void ui(final Container pane){
        JLabel test = new JLabel("test frame");
        pane.add(test);
        System.out.println("Frame works.");

    }

}

now if you include graphics in this class, everytime you call up repaint(), it will call the function paintComponent(Graphics g). good luck :)