HashMap以List作为Key值存在的问题

//Test1
List<String> list1 = new ArrayList<String>();
list1.add("Elem1");
list1.add("Elem2");
Map<List<String>, String> map = new HashMap<List<String>, String>();
map.put(list1, "Can get value.");
System.out.println("Elements of list1: "+list1);
List<String> list2 = new ArrayList<String>();
list2.add("Elem1");
list2.add("Elem2");
System.out.println("Elements of list2: "+list1);
System.out.println("Test1. Get value from HashMap(Key: list1) by the key list2: "+map.get(list2)+"\n");

//Test2
list1 = new ArrayList<String>();
list1.add("Elem1");
map = new HashMap<List<String>, String>();
map.put(list1, "Can get value.");//list1 only one element, and it's hash code is 67040897
list1.add("Elem2");//Add one element, even though ArrayList is a kinds of reference type, but map keys' hash code not change.
System.out.println("Elements of list1: "+list1);
list2 = new ArrayList<String>();
list2.add("Elem1");
list2.add("Elem2");
System.out.println("Elements of list2: "+list2);
System.out.println("Test2. Get value from HashMap(Key: list1) by the key list2: "+map.get(list2)+"\n");

//Test3
list1 = new ArrayList<String>();
list1.add("Elem1");
map = new HashMap<List<String>, String>();
map.put(list1, "Can get value.");
list1.add("Elem2");
System.out.println("Elements of list1: "+list1);
Map<List<String>, String> tempMap = new HashMap<List<String>, String>();
tempMap.putAll(map);//Will be recalculate the keys' hash code
list2 = new ArrayList<String>();
list2.add("Elem1");
list2.add("Elem2");
System.out.println("Elements of list2: "+list2);
System.out.println("Test3. Get value from HashMap(Key: list1) by the key list2: "+tempMap.get(list2));