Map<String, String> mapA = new LinkedHashMap<>();
mapA.put("name", "Rocket Skates");
mapA.put("price", "12.75");
mapA.put("color", "yellow");

Map<String, String> mapB = new LinkedHashMap<>();
mapB.put("price", "15.25");
mapB.put("color", "red");
mapB.put("year", "1974");

Map<String, String> mapC = new LinkedHashMap<>();
mapC.putAll(mapA);
mapC.putAll(mapB);