### Question:
StringUtils { public static String toString(Object o, String defaultVal) { return o == null ? defaultVal : o.toString(); }  static boolean isEmpty(CharSequence cs); static boolean isNotEmpty(CharSequence cs); static boolean isBlank(CharSequence cs); static boolean isNotBlank(CharSequence cs); static String defaultString(final Object str); static String toString(Object o, String defaultVal); static String toString(Object o); static final String EMPTY; }### Answer:
@Test public void testToString() { Assert.assertEquals(null, StringUtils.toString(null)); Assert.assertEquals("Bean:11", StringUtils.toString(new Bean("11"))); Assert.assertEquals(null, StringUtils.toString((Object) null, null)); Assert.assertEquals("1", StringUtils.toString((Object) null, "1")); Assert.assertEquals("Bean:11", StringUtils.toString(new Bean("11"), null)); }