java - JPanel does not appear correctly while extending JFrame -

this homework.

my directions: class guessgame: class contains main function creates jframe object, sets jframe’s size, visibility , exit.

class guessgameframe: guessgameframe class extends jframe. guessgameframe class has variables , methods defined in class jframe.

i not 100% sure problem believe jpanel not working correctly

any appreciated, if left out important please let me know , can add more detail.

main class:

public class guessgame {               public static void main(string[] args){                   guessgameframe localguessgameframe = new guessgameframe();                   localguessgameframe.setvisible(true); //set visible                   localguessgameframe.setsize(380,175); // set size 380 width 175 height                   localguessgameframe.setdefaultcloseoperation(localguessgameframe.exit_on_close); // needed enable red x button close program              } } 

extended class:

import javax.swing.*; import java.awt.*;  public class guessgameframe extends jframe     {      private int lastdistance; // distance between last guess , number     private color background; // background color of application      private jframe f;     static jpanel p;     private jbutton b1;     private jlabel l1;     private jlabel l2;     jtextfield t1 = new jtextfield(8);     private jlabel l3;      //declare constructor     public guessgameframe()     {     //create our jframe     f = new jframe("guessing game");      //create our panel         p = new jpanel();         p.setbackground(color.magenta); // background color magenta          //create our labels         l1 = new jlabel("i have number between 1 , 1000.");         l2 = new jlabel("can guess number? enter first guess:.");         l3 = new jlabel("guess result appears here.");         //create our button         b1 = new jbutton("new game");          //add button , label panel         p.add(l1); // adds label 1         p.add(l2); // adds label 2         p.add(t1); // adds textfield 1         p.add(l3); // adds label 3         p.add(b1); // adds button 1          //add panel jframe         f.add(p);     } } 

screenshot of output window when executed:

i expect this:

you need remove jframe f in guessgameframe class because guessgameframe jframe:

and update code:

f = new jframe("guessing game"); this.settitle("guessing game");

f.add(p); this.getcontentpane().add(p);