The inner loop of the toString method of class Vector in java.util
looks like this:

for (int i = 0 ; i <= max ; i++) {
String s = e.nextElement().toString();
buf.append(s);
if (i < max) {
buf.append(", ");
}
}

Observe that if any item in the Vector is null, a NullPointerException
will be thrown. This is not desirable. Better would be to code it as

for (int i = 0 ; i <= max ; i++) {
buf.append(e.nextElement().toString());
if (i < max) {
buf.append(", ");
}
}

The append method of StringBuffer will handle the case of a null pointer
properly.

============================================================================

daniel.indrigo@Canada 1997-08-26

I still get this problem in 1.2_EA2 on Solaris and win32

import java.util.*;

public class ddd {
public static void main(String args[]) {
Integer a = new Integer(1);
Integer b = new Integer(2);
Integer c = new Integer(3);
Integer d = new Integer(4);
Vector v = new Vector(0,2);
v.setSize(5);
System.out.println("Inside main()");
System.out.println(v.size());
v.addElement(a);
System.out.println("Add a, size is " + v.size() +", v = " + v);
v.addElement(b);
System.out.println("Add b, size is " + v.size() +", v = " + v);
v.addElement(c);
System.out.println("Add c, size is " + v.size() +", v = " + v);
v.insertElementAt(d, 2);
System.out.println("Insert d at 2, size is " + v.size() +", v = " + v);
}
}

Inside main()
5
java.lang.NullPointerException
at java.util.Vector.toString(Vector.java)
at java.lang.StringBuffer.append(StringBuffer.java)
at ddd.main(ddd.java:14)