PdfPageLabel { public static PdfPageLabel newInstanceWithLabel(String label, PdfLabelNumberingStyle numberingStyle, int logicalPageNumber) { if (logicalPageNumber < 1) { throw new InvalidParameterException("Input page number must be positive."); } if (label == null) { throw new InvalidParameterException("Input label cannot be null."); } if (numberingStyle == null) { throw new InvalidParameterException("Input numbering style cannot be null."); } return new PdfPageLabel(label, numberingStyle, logicalPageNumber); } private  PdfPageLabel(String labelPrefix, PdfLabelNumberingStyle numberingStyle, int logicalPageNumber); String getLabelPrefix(); PdfLabelNumberingStyle getNumberingStyle(); int getLogicalPageNumber(); @Override String toString(); @Override int hashCode(); @Override boolean equals(Object other); static PdfPageLabel newInstanceWithoutLabel(PdfLabelNumberingStyle numberingStyle, int logicalPageNumber); static PdfPageLabel newInstanceWithLabel(String label, PdfLabelNumberingStyle numberingStyle,
            int logicalPageNumber);  }
@Test(expected = IllegalArgumentException.class) public void testNullLabel() { PdfPageLabel.newInstanceWithLabel(null, PdfLabelNumberingStyle.ARABIC, 1); }
@Test(expected = IllegalArgumentException.class) public void testNullStyle() { PdfPageLabel.newInstanceWithLabel("dsdsadsa", null, 1); }
@Test(expected = IllegalArgumentException.class) public void testNegativePhysicalNumb() { PdfPageLabel.newInstanceWithLabel("dsdsadsa", PdfLabelNumberingStyle.ARABIC, -1); }