阅读以下程序,请写出该程序的功能。 import javax.swing.*; import java.awt.*;import java.awt.event.*; class MyScrollBar extends JscrollBar{ public MyScrollBar(int init, int len, int low, int high){ super(JScrollBar. HORIZONTAL, init,len,low,high); } } class MyWindow extends JFrame implements AdjustmentListener{ private JTextField text; MyWindow(String s){ super(s); MyScrollBar myBar=new MyScrollBar(10,10,0,255); Container con=this. getContentPane(); con. setLayout(new GridLayout(2,1)); this. setSize(200,100); this. setLocation(100,100); myBar.addAdjustmentListener(this); text=new JTextField( "" ,20); con. add(text);con.add(myBar); this.setVisible(true); } public void adjustmentValueChanged(AdjustmentEvent e){ MyScrollBar myBar=(MyScrollBar)e.getAdjustable(); text.setText( "" +myBar.getValue()); } } public class Class1{ public static void main(String[]args){ MyWindow myWindow=new MyWindow( " text5_4 " ); } }