@Test
public void testJoin() throws Exception {

    String[] src = new String[] { "1", "2", "3" };
    String arrayString = StringUtils.join(src, "");
    Assert.assertEquals(arrayString, "123");
    arrayString = StringUtils.join(src, ",");
    Assert.assertEquals(arrayString, "1,2,3");
    arrayString = StringUtils.join(new String[] {}, ",");
    Assert.assertEquals(arrayString, "");
    arrayString = StringUtils.join(null, "");
    Assert.assertEquals(arrayString, "");
}