swing - Java inheritance or GUI gone wrong -

despite tips, i'm still getting 1 wrong. end 1 basic window , 1 features, without basic ones previous window. instead, 1 new window combining basic , new features. here code i've got: (also approach advise?)

package windows;  import java.awt.*; import javax.swing.*;  public abstract class windowtemplate extends jframe {  /**  * create gui , show it. thread safety, method should  * invoked event-dispatching thread.  */ public windowtemplate () {  jframe myframe = new jframe("my first window"); myframe.setdefaultcloseoperation(jframe.exit_on_close); myframe.setvisible(true); myframe.setsize(550, 450); myframe.setlocationrelativeto(null);  // jlabel emptylabel = new jlabel(""); // emptylabel.setpreferredsize(new dimension(550, 450));  // myframe.getcontentpane().setlayout(new cardlayout()); // myframe.getcontentpane().add(emptylabel, borderlayout.center);  // myframe.pack();  }  } 

now 1 meant "extended":

package windows;  import java.awt.*; import javax.swing.*;  public class a_welcome extends windowtemplate {  public a_welcome() {  jpanel area = new jpanel();  jlabel text = new jlabel("one line line , line"); // , jlabel.center);  // text.setbounds(80, 400, 400, 50); add(area);  // area.setlayout(null); area.add(text, new cardlayout());  // area.add(text); // , borderlayout.center);  font font = new font("sansserif", font.bold, 30); text.setfont(font); text.setforeground(color.green); area.setbackground(color.darkgray); area.setsize(550, 450);  }  }  // timer-after 5 seconds-go next window (countdown in bottom right corner) 

and main:

package windows;  public class launcher {  public static void main(string[] args) {  // schedule job event-dispatching thread: // creating , showing application's gui. javax.swing.swingutilities.invokelater(new runnable() {     public void run() {          // windowtemplate.createwindow();         // a_welcome.createwindow();           a_welcome window = new a_welcome();          window.setvisible(true);     } });  }  } 

-- alternatively --

public class windowtemplate extends jframe {  // constructor public windowtemplate() {     init(); }  public void init() {     // add basic components     jframe myframe = new jframe("my first window");     myframe.setdefaultcloseoperation(jframe.exit_on_close);     myframe.setvisible(true);     myframe.setsize(550, 450);     myframe.setlocationrelativeto(null); } } 

and

public class a_welcome extends windowtemplate {  public a_welcome() {     super(); }  @override public void init() {     super.init(); // important base stuff     // add other components     jpanel area = new jpanel();     jlabel text = new jlabel("one line line , line");     add(area);     area.add(text, new cardlayout());      font font = new font("sansserif", font.bold, 30);     text.setfont(font);     text.setforeground(color.green);     area.setbackground(color.darkgray);     area.setsize(550, 450);  } } 

sorry lots of code , help!

i'm not quite sure problem is, windowtemplate is jframe, don't want create new jframe in constructor rather "apply" method this instead of myframe. try this:

public windowtemplate() {     super("my first window");     this.setdefaultcloseoperation(jframe.exit_on_close); // "this" optional     setvisible(true);     setsize(550, 450);     setlocationrelativeto(null); } 

and

public a_welcome() {     super(); // implicit, because a_welcome extends windowtemplate, has got constructor without parameters     //[add more stuff here]  } 

when you're creating new a_welcome, constructor call super constructor, windowtemplate in turn call jframe constructor