Two ways to initialize map and list in Java

First method (Common method):

Initialize listlist<string> list = new arraylist</string><string> () List.add ("string1"); List.add (" String2 ");//some other List.add () code......list.add (" Stringn "); Initialize mapmap<string object= "" > Map = new hashmap<string object= "" > () map.put ("Key1", "value1"); Map.put (" Key2 "," value2 "),//... some other map.put () codemap.put (" KeyN "," Valuen ");

Second method (double parenthesis initialization method)

Initialize list    list<string> list = new Arraylist<string> () {{        Add ("string1");        Add ("string2");        Some other add () code        ... Add ("Stringn");}    ;     Initialize map    map<string string= "" > Map = new hashmap<string object= "" > () {        put ("Key1", "value1");        Put ("Key2", "value2");        ..... some other put () code        put ("KeyN", "Valuen");}    };

　　

Two ways to initialize map and list in Java