Some writing methods for List and Map initialization in Java

Before I discovered the new writing method in Java, I always initialized List and Map like this:

//初始化List
    List list = new ArrayList();
    list.add("m.sbmmt.com");
    list.add("string2");
    //some other list.add() code......
    list.add("stringN");

    //初始化Map
    Map map = new HashMap();
    map.put("key1", "value1");
    map.put("key2", "value2");
    //.... some other map.put() code
    map.put("keyN", "valueN");
    

It’s so troublesome. . . . . One day I came across such a method:

//初始化List
    List list = new ArrayList(){{
    add("string1");
    add("string2");
    //some other add() code......
    add("stringN");
    }};

    //初始化Map
    Map map = new HashMap(){{
    put("key1", "value1");
    put("key2", "php.cn");
    //.... some other put() code
    put("keyN", "valueN");
    }};
    

Although it seems that I haven’t written much less code, I personally feel that this method is much simpler and smoother haha~
Example, now Yiju editor tested two examples of List to make it simpler

Method one:
Use the mutual conversion method between Array and ArrayList, the code is as follows:

rrayList list = new ArrayList(Arrays.asList("Ryan", "Julie", "Bob"));

Method two:
Use The add method of ArrayList completes the initialization assignment. The code is as follows:

List list = new ArrayList(){{
add("A");
add("B");
}}

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