Question

Let’s consider the following code:

public class MyPanel extends JPanel {

    private long secretInfo = ...

}

JPanel is Serializable. However, MyPanel should not be Serializable ever, because it contains sensitive information.

How to cleanly cancel/prevent the inherited Serializable aspect from JPanel?

Answer 1

You can use one of the following approaches:

public class MyPanel extends JPanel {
    private long secretInfo = ...

    // refuse to be serialized!
    private void writeObject(ObjectOutputStream out) throws IOException {
        throw new IllegalStateException("MyPanel cannot be serialized");
    }
}

or

public class MyPanel extends JPanel {
    // flag the serialization mechanism to ignore
    // sensitive information
    private transient long secretInfo = ...
}