### Question:
HBaseFileSystem { public synchronized static HBaseFileSystem instance() { if (fs == null) { fs = new HBaseFileSystem(); log.debug("HBase File System has been init."); } return fs; } private  HBaseFileSystem(); synchronized static HBaseFileSystem instance(); HBaseFileScanner scan(); long count();  }### Answer:
@Test public void testInstance() { System.out.println("instance"); HBaseFileSystem fs1 = HBaseFileSystem.instance(); HBaseFileSystem fs2 = HBaseFileSystem.instance(); assertTrue(fs1 == fs2); }