add a jpanel to the jframe

Source code

  
package myPackage;

import java.awt.Color;

import javax.swing.JFrame;
/*JPanle import below
 make sure to import 
 */
import javax.swing.JPanel;


public class myClass{
 
 public static void main(String[]args){
  
 JFrame frame = new JFrame();
 /*create a JPanel object Here*/
JPanel panel = new JPanel();
 
frame.setDefaultCloseOperation
          (JFrame.EXIT_ON_CLOSE);
  
frame.setTitle("create Jpanel");
  
frame.setVisible(true);
  
frame.setSize(450, 500);
  
panel.setBackground(Color.BLACK); 

frame.add(panel);
  
 }
 
}

  

And if you run this it would look like

Create a method for JPanel in java and add to the frame..So for this we'll hava two classes a main and a mehthods class. so let's work

this is the main class

package myPackage;
 
public class myMain {
 public void main(String[]args){
  myClass clas = new myClass();
 }
}

mehtods class

package myPackage;

import java.awt.Color;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class myClass {
 
/*create a Jframe here*/

JFrame frame = new JFrame();

/*create a JPanel here*/

JPanel panel = new JPanel();

public myClass() {
 frame();
}
public void frame(){
 frame.setDefaultCloseOperation
          (JFrame.EXIT_ON_CLOSE);
 
 frame.setTitle("create Jpanel");
   
 frame.setVisible(true);
   
 frame.setSize(450, 500);
 /*join both together
  * cause we are call 
  * this mehtod in
  * the constructer
  * so call the panel
  *  method
  */
 panel();
}
  public void panel(){
   
 panel.setBackground(Color.black);
frame.add(panel);
  
  }
}

and same result

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