java中Map和List初始化的N种方法总结

//初始化List  
List<string> list = new ArrayList<string><string>();  
list.add("string1");  
list.add("string2");  
list.add("stringN");  

//初始化Map  
Map</String , Object> map = new HashMap</String , Object>();  
map.put("key1", "value1");  
map.put("key2", "value2");  
map.put("keyN", "valueN");  

//初始化List  
 List<string> list = new ArrayList<string>(){{  
     add("string1");  
     add("string2");  
     add("stringN");  
 }};  
  
 //初始化Map  
 Map</String , String> map = new HashMap</String , Object>(){{  
     put("key1", "value1");  
     put("key2", "value2");  
     put("keyN", "valueN");  
 }}; 

Map map = Stream.of(1,2,3,4).collect(Collectors.toMap(o -> o,integer -> integer,(o, o2) -> o2,HashMap::new));
       System.out.println(JSONObject.tojsONString(map));

List list = Stream.of(1,2,3,4).collect(Collectors.toList());
       System.out.println(JSONObject.toJSONString(list));

ArrayList<String> list = new ArrayList(Arrays.asList("Tom", "Jerry", "Mike"));  

    List<Integer> useCases = new ArrayList<Integer>();
     Collections.addAll(useCases, 47, 48, 49, 50);

List<String> list = new ArrayList<String>(2) {{
    add("1");
    add("2");
}};

Map<String, Object> map = new HashMap<String, Object>(2) {{
    put("key1", "obj1");
    put("key2", "obj2");
}};