List.clear()
List result = new ArrayList(); List list = new ArrayList(); list.add("foo"); System.out.println("list: " + list); // [foo] result.add(list); System.out.println("result: " + result); // [[foo]] list.clear(); System.out.println("list: " + list); // [] System.out.println("result: " + result); // [[]] list.add("bar"); System.out.println("list: " + list); // [bar] System.out.println("result: " + result); // [[bar]] result.add(list); System.out.println("result: " + result); // [[bar], [bar]]
Map.clear()
List result = new ArrayList(); Map map = new HashMap(); map.put("key", "value"); System.out.println("map: " + map); // {key=value} result.add(map); System.out.println("result: " + result); // [{key=value}] map.clear(); System.out.println("map: " + map); // {} System.out.println("result: " + result); // [{}] map.put("foo", "bar"); System.out.println("map: " + map); // {foo=bar} System.out.println("result: " + result); // [{foo=bar}] result.add(map); System.out.println("result: " + result); // [{foo=bar}, {foo=bar}]