Java HashMap을 직접 초기화하는 방법은 무엇입니까?

Map<String,String> test = 
    new HashMap<String, String>{"test":"test","test":"test"};

// For up to 10 elements
Map<String, String> test1 = Map.of("a", "b", "c", "d");

// For any number of elements
import static java.util.Map.entry;
Map<String, String> test2 = Map.ofEntries(entry("a", "b"), entry("c", "d"));

Map<String, String> myMap = new HashMap<String, String>() {{
    put("a", "b");
    put("c", "d");
}};

Map<String, String> myMap = createMap();

private static Map<String, String> createMap() {
    Map<String,String> myMap = new HashMap<String,String>();
    myMap.put("a", "b");
    myMap.put("c", "d");
    return myMap;
}