@Test public void testEmpty() { assertEquals("", NDC.pop()); }
public static String pop() { int next = size(); if (next == 0) { return ""; } int last = next - 1; String key = PREFIX + last; String val = MDC.get(key); MDC.remove(key); return val; }
NDC { public static String pop() { int next = size(); if (next == 0) { return ""; } int last = next - 1; String key = PREFIX + last; String val = MDC.get(key); MDC.remove(key); return val; } }
NDC { public static String pop() { int next = size(); if (next == 0) { return ""; } int last = next - 1; String key = PREFIX + last; String val = MDC.get(key); MDC.remove(key); return val; }  }
NDC { public static String pop() { int next = size(); if (next == 0) { return ""; } int last = next - 1; String key = PREFIX + last; String val = MDC.get(key); MDC.remove(key); return val; }  static void push(String val); static String pop(); }
NDC { public static String pop() { int next = size(); if (next == 0) { return ""; } int last = next - 1; String key = PREFIX + last; String val = MDC.get(key); MDC.remove(key); return val; }  static void push(String val); static String pop(); final static String PREFIX; }