A DESCRIPTION OF THE PROBLEM :
The JPasswordField documentation specifies that you can set the echo character to 0 to cause the password field to print normal characters, rather than the echo character. It should be made clear in the docs that this does not mean setting the echo character to '0', but to '\u0000'. That is , you should use unicode 0, not the character 0.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
I expected something as described above. It should be noted that the Unicode "NULL" character is needed, not the character '0'.
ACTUAL -
setEchoChar

public void setEchoChar(char c)

    Sets the echo character for this JPasswordField. Note that this is largely a suggestion, since the view that gets installed can use whatever graphic techniques it desires to represent the field. Setting a value of 0 indicates that you wish to see the text as it is typed, similar to the behavior of a standard JTextField.

URL OF FAULTY DOCUMENTATION :
http://java.sun.com/javase/6/docs/api/javax/swing/JPasswordField.html