String to HashMap JAVA

Question

I have a Java Property file and there is a KEY as ORDER. So I retrieve the VALUE of that KEY using the getProperty(

Answer 1

In one line :

HashMap<String, Integer> map = (HashMap<String, Integer>) Arrays.asList(str.split(",")).stream().map(s -> s.split(":")).collect(Collectors.toMap(e -> e[0], e -> Integer.parseInt(e[1])));

Details:

1) Split entry pairs and convert string array to List<String> in order to use java.lang.Collection.Stream API from Java 1.8

Arrays.asList(str.split(","))

2) Map the resulting string list "key:value" to a string array with [0] as key and [1] as value

map(s -> s.split(":"))

3) Use collect terminal method from stream API to mutate

collect(Collector<? super String, Object, Map<Object, Object>> collector)

4) Use the Collectors.toMap() static method which take two Function to perform mutation from input type to key and value type.

toMap(Function<? super T,? extends K> keyMapper, Function<? super T,? extends U> valueMapper)

where T is the input type, K the key type and U the value type.

5) Following lambda mutate String to String key and String to Integer value

toMap(e -> e[0], e -> Integer.parseInt(e[1]))

Enjoy the stream and lambda style with Java 8. No more loops !

Answer 2

try

 String s = "SALES:0,SALE_PRODUCTS:1,EXPENSES:2,EXPENSES_ITEMS:3";
    HashMap<String,Integer> hm =new HashMap<String,Integer>();
    for(String s1:s.split(",")){
       String[] s2 = s1.split(":");
        hm.put(s2[0], Integer.parseInt(s2[1]));
    }

Answer 3

I recommend using com.fasterxml.jackson.databind.ObjectMapper (Maven repo link: https://mvnrepository.com/artifact/com.fasterxml.jackson.core) like

final ObjectMapper mapper = new ObjectMapper();
Map<String, Object> mapFromString = new HashMap<>();
try {
    mapFromString = mapper.readValue(theStringToParse, new TypeReference<Map<String, Object>>() {
        });
} catch (IOException e) {
    LOG.error("Exception launched while trying to parse String to Map.", e);
}

Answer 4

In one line (updated)

String s = prop.getProperty("ORDER");

Map<String, Integer> orderMap = Arrays.stream(s.split(",")).map(s -> s.split(":")).collect(Collectors.toMap(s -> s[0], s -> Integer.parseInt(s[1])));