import javax.swing.*;
import java.awt.*;

public class TextScroll{
  JTextArea2 jta;
  JScrollPane jsp;

  public TextScroll(){
    jta = new JTextArea2(5, 20);
    jsp = new JScrollPane(jta);
  }

  public JScrollPane getJsp(){
    return jsp;
  }
  
  public JTextArea2 getJta(){
    return jta;
  }
  
  public static void main(String[] args) throws Exception{
    Rectangle rec;
    int h, c;
    boolean nob;

    JFrame frame = new JFrame("Scrollint Test");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    TextScroll st = new TextScroll();
    JScrollPane js = st.getJsp();
    frame.getContentPane().add(js);
    frame.setBounds(0, 0, 200, 135);
    frame.setVisible(true);
    
    JTextArea2 t = st.getJta();
    t.setFont(new Font("Monospaced", Font.BOLD, 14));
    h = t.getLineHeight();
    c = 0;
    nob = true;
    while (++c < 11){
      rec = t.getVisibleRect();
      rec.y += h;
      t.scrollRectToVisible(rec);
      if (nob){
        t.append("Love to live: " + c + "\n");
      }
      else{
        t.append("Live to love: " + c + "\n");
      }
      Thread.sleep(1500);
      nob = (! nob);
    }
    t.setBackground(Color.yellow);
  }
}

class JTextArea2 extends JTextArea{

  public JTextArea2(int col, int row){
    super(col, row);
  }

  public int getLineHeight(){
    return getRowHeight();
  }
}