In using javax.swing.JTextField, it throws java.io.NotSerializableException
if a given parameter is a String of Japanese characters (non-ascii characters)
and try to serialize. JTextField implements Serializable, and when the string
consists of ascii characters, no exception is thrown.

The following code is the sample code showing this synopsis. Line 6 causes
the exception when the parameter given to the constructor is a String of
Japanese characters (though Japanese characters cannot be shown correctly
in this text field).



     1 import java.io.*;
     2 import javax.swing.*;
     3
     4 public class Test {
     5 public static void main(String[] args)throws Exception {
     6 JTextField ta = new JTextField("Ƚ");
     7 ObjectOutputStream out = new ObjectOutputStream(System.out);
     8 out.writeObject(ta);
     9 out.close();
    10 }
    11 }



% java Test > tmpfile
Exception in thread "main" java.io.NotSerializableException: java.lang.Object
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1054)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:278)
        at java.util.Hashtable.writeObject(Hashtable.java:801)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:324)
        at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:795)
        at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1294)
        at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1245)
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1052)
        at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1330)
        at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1302)
        at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1245)
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1052)
        at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1330)
        at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1302)
        at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1245)
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1052)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:278)
        at Test.main(Test.java:8)