class Segment extends Box{
        JProgressBar progress;
        JLabel label1,label2,label3;
        JButton button;
        public Segment(){
                createVerticalBox();
                progress = new JProgressBar();
                label1 = new JLabel();
                label2 = new JLabel();
                label3 = new JLabel();
                button = new JButton();

                Box hbox1 = Box.createHorizontalBox();
                hbox1.add(progress);
                hbox1.add(button);

                Box hbox2 = Box.createHorizontalBox();
                hbox2.add(label2);
                hbox2.add(label3);
                this.add(label1);
                this.add(hbox1);
                this.add(hbox2);
        }
}

 javac Segment.java 
Segment.java:9: cannot find symbol
symbol  : constructor Box()
location: class javax.swing.Box
        public Segment(){
                        ^
1 error