FULL PRODUCT VERSION :
java version "1.6.0-beta2"
Java(TM) SE Runtime Environment (build 1.6.0-beta2-b86)
Java HotSpot(TM) Client VM (build 1.6.0-beta2-b86, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Windows 2000 [Version 5.00.2195]

A DESCRIPTION OF THE PROBLEM :
According to the documentation

JTextArea jTextArea = new JTextArea("test");

should be equivalent to

JTextArea jTextArea = new JTextArea();
jTextArea.append("test");

This is not the case. The constructor with the String parameter resets the caret's position to 0 while the constructor+append combination places the caret at the end of the text.

If the contents of the JTextArea are displayed in a JScrollPane, using these different constructors yields different results for the behaviour of the viewport.

The fix is obvious. In JTextArea.java, line 192

select(0, 0);

should be replaced by

int caretPos = text.length();
select(caretPos, caretPos);

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Please run the attached source code and check the output to System.out and the contents of the viewport.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Using the constructor+append combination results in the desired behaviour. The caret's position is 7 and the viewport shows the last lines.
ACTUAL -
Using the constructor with the String parameter sets the caret's position to 0. The viewport shows the first lines.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
/*
 * JTextAreaBugdemo.java
 */

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;

public class JTextAreaBugdemo extends JFrame {
    
    static private JTextArea jTextArea;
    
    public JTextAreaBugdemo() {
        JFrame.setDefaultLookAndFeelDecorated(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
        jTextArea = new JTextArea("line 0\n");
// jTextArea = new JTextArea();
// jTextArea.append("line 0\n");
        
        System.out.println("caret position = " + jTextArea.getCaretPosition());
        
        getContentPane().add(new JScrollPane(jTextArea));
        pack();
        setVisible(true);
    }
    
    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new JTextAreaBugdemo();
                jTextArea.append("line 1\n");
                jTextArea.append("line 2\n");
                jTextArea.append("line 3\n");
                jTextArea.append("line 4\n");
                jTextArea.append("line 5");
            }
        });
    }
}
---------- END SOURCE ----------