By convention, an API must throw a null pointer exception for a null input
parameter unless the javadoc spec declares otherwise. A styled string
constructor with a non-null input String str and a null reference for the
attributes parameter does not throw a NullPointerException. See the
following test program:

   public Status ConstructorAttributes() {
      StyledString aStyledString;
      String aStringNull = null;
      AttributeSet anAttributeSetNull = null;
      AttributeSet anAttributeSet = new TextAttributeSet();
      // null string and attributes
      try {
         aStyledString = new StyledString(aStringNull, anAttributeSetNull);
         return Status.failed("failed to throw NullPointerException for constructor with null string and attribute set references");
      } catch (NullPointerException e) {
         // OKAY
      }
      // null string and non-null attributes
      try {
         aStyledString = new StyledString(aStringNull, anAttributeSet);
         return Status.failed("failed to throw NullPointerException for constructor with null string reference and non-null attribute set");
      } catch (NullPointerException e) {
         // OKAY
      }
      // non-null string and null attributes
      try {
         aStyledString = new StyledString("aString", anAttributeSetNull);
         return Status.failed("failed to throw NullPointerException for constructor with non-null string reference and null attribute set");
      } catch (NullPointerException e) {
         // OKAY
      }