how to import one class to another

Question

I have two classes, one of them is main main. I need to import another class into the maine. I understand that you need to create an object of this class, but how to implement it?

// basic main

import javax.swing.*;

import java.awt.*;

public class Main {

    public static void main(String[] args) {

        int w = 640;

        int h = 480;

        JFrame f = new JFrame();
        Object g = null;
        Drawing dc = new Drawing(Graphics g);
        f.setSize(w, h);
        f.setTitle("Digits");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setVisible(true);
    }
}

---

// another class which i need import 

import java.awt.*;

import java.awt.geom.*;

import javax.swing.*;


class Drawing extends JComponent {

    public Drawing() {

    }
    @Override
    protected void paintComponent(Graphics g){
        Graphics2D g2d = (Graphics2D) g;

        RenderingHints rh = new RenderingHints(
                RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);
        g2d.setRenderingHints(rh);

        Path2D.Double curve = new Path2D.Double();
        curve.moveTo(250,400);
        curve.curveTo(350,300,500,300,600,400);
        g2d.draw(curve);
    }
}

Answer 1

If it's in the same package, you don't need to import the class - simply create an object of the class like below:

Drawing draw = new Drawing();// this should work for you.

If it's not in the same package, just import the package name with class Drawing .

package packageName// assuming you have this line already in your code

import packageNameWhichContainsTheClassYouWantToImport.Drawing  
import javax.swing.*;

import java.awt.*;

public class Main {

    public static void main(String[] args) {

        int w = 640;

        int h = 480;

        JFrame f = new JFrame();
        Object g = null;
        Drawing dc = new Drawing(Graphics g);
        f.setSize(w, h);
        f.setTitle("Digits");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setVisible(true);
    }
}

You can also create an object without importing the class by using fully qualified name of the class, like

myPackage.Drawing draw = new Drawing();