Name: dsR10051 Date: 11/16/2000


The constructor
java.awt.datatransfer.UnsupportedFlavorException(DataFlavor flavor)
throws NullPointerException if flavor parameter is null.
Thare are three resons to consider this behavior as incorrect:
1. It seems to be poor behavior for exception to fail
   an initialization time.
2. The NullPointerException is subclass of java.lang.RuntimeException,
   but UnsupportedFlavorException is not. So, if method foo () declares the throwing
   of UnsupportedFlavorException, exception should be handled and processed by user.
   It may be not done for NullPointerException. NPE in this case may be cause
   abnormal execution of program.
3. It is inconsistent behavior for full exception hierarchy. I could not find
   other Exception subclass that documents the throwing of another exception
   in constructor.

Here is a minimized test:

import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.datatransfer.DataFlavor;

public class UnsupportedFlavorExceptionTest01 {
    public static void main(String[] args) {
        try {
            foo();
        } catch (UnsupportedFlavorException ufe) {
        }
        System.out.println("OKAY");
        System.exit(0);
    }

    public static void foo() throws UnsupportedFlavorException{
        throw new UnsupportedFlavorException((DataFlavor) null);
    }
}

--- Output ---
%java -version
java version "1.4.0beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0beta-b40)
Java HotSpot(TM) Client VM (build 1.4beta-B40, mixed mode)
%java UnsupportedFlavorExceptionTest01
Exception in thread "main" java.lang.NullPointerException
        at java.awt.datatransfer.UnsupportedFlavorException.<init>(UnsupportedFlavorException.java:36)
        at UnsupportedFlavorExceptionTest01.foo(UnsupportedFlavorExceptionTest01.java:15)
        at UnsupportedFlavorExceptionTest01.main(UnsupportedFlavorExceptionTest01.java:7)

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