How to convert a string to a HashMap?

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() method after loading the property file like below.:

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

then

s ="SALES:0,SALE_PRODUCTS:1,EXPENSES:2,EXPENSES_ITEMS:3";

I need to create a HashMap from above string. SALES,SALE_PRODUCTS,EXPENSES,EXPENSES_ITEMS should be KEY of HashMap and 0,1,2,3, should be VALUEs of KEYs.

If it's hard corded, it seems like below:

Map<String, Integer> myMap  = new HashMap<String, Integer>();
myMap.put("SALES", 0);
myMap.put("SALE_PRODUCTS", 1);
myMap.put("EXPENSES", 2);
myMap.put("EXPENSES_ITEMS", 3);

If it really is for the given String, keep the hardcoded solution... If not please tell us what you have tried so far and what your problem is. — pgras, May 09 '12 at 10:47
@pgras i have edited my post. i think now it's not complicated to understand. — Bishan, May 09 '12 at 10:54
Does this answer your question? [Convert string representing key-value pairs to Map](https://stackoverflow.com/questions/14768171/convert-string-representing-key-value-pairs-to-map) — Volo Myhal, Apr 07 '21 at 10:34

KARASZI István · Answer 1 · 2021-12-29T15:47:43.427

70

You can do that with Guava's Splitter.MapSplitter:

Map<String, String> properties = Splitter.on(",")
    .withKeyValueSeparator(":")
    .split(inputString);

edited Dec 29 '21 at 15:47

answered May 09 '12 at 10:46

KARASZI István

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Please note this returns an immutable list – xilef Jan 17 '17 at 05:29
1

@xilef and that is the best part of it! – KARASZI István Jan 17 '17 at 06:17
It returns me a collection of key-value pairs whereas I want a HashMap – Sankalp Apr 17 '19 at 02:01
@Sankalp it returns a `Map` not key-value pairs. – KARASZI István May 16 '19 at 07:44

Xavi López · Accepted Answer · 2015-05-15T07:44:47.150

55

Use the String.split() method with the , separator to get the list of pairs. Iterate the pairs and use split() again with the : separator to get the key and value for each pair.

Map<String, Integer> myMap = new HashMap<String, Integer>();
String s = "SALES:0,SALE_PRODUCTS:1,EXPENSES:2,EXPENSES_ITEMS:3";
String[] pairs = s.split(",");
for (int i=0;i<pairs.length;i++) {
    String pair = pairs[i];
    String[] keyValue = pair.split(":");
    myMap.put(keyValue[0], Integer.valueOf(keyValue[1]));
}

edited May 15 '15 at 07:44

answered May 09 '12 at 10:46

Xavi López

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using a foreach you can save a row! :) – Ayoub Feb 19 '14 at 15:30
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the String.split() method link is broken – inquisitive May 15 '15 at 07:38
@KumarAnkit comma being a hard separator is one of the OP's assumptions or requirements. This answer, as could not be otherwise, builds on that. – Xavi López Dec 19 '18 at 10:58
1

what if your any key, value contains comma? – jay rangras Oct 24 '20 at 11:06
Wouldn't using an ObjectMapper be better and faster than this? – Jet Ezra Nov 28 '22 at 11:41

score 30 · Answer 3 · answered Jul 09 '15 at 10:22

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 !

I may get flagged but I gotta say, holy shit! I never knew Java was this powerful. — Neerkoli, Dec 05 '16 at 11:16

score 7 · Answer 4 · answered Aug 02 '17 at 16:00

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);
}

score 5 · Answer 5 · answered Jan 08 '21 at 12:17

5

USING JAVA 8:

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

answered Jan 08 '21 at 12:17

Chinmoy

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score 3 · Answer 6 · answered May 09 '12 at 10:48

3

Assuming no key contains either ',' or ':':

Map<String, Integer> map = new HashMap<String, Integer>();
for(final String entry : s.split(",")) {
    final String[] parts = entry.split(":");
    assert(parts.length == 2) : "Invalid entry: " + entry;
    map.put(parts[0], new Integer(parts[1]));
}

answered May 09 '12 at 10:48

Romain

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what options can we use when we get a **,** – KumarAnkit Dec 19 '18 at 10:51

score 3 · Answer 7 · answered Jun 19 '15 at 14:50

You can also use JSONObject class from json.org to this will convert your HashMap to JSON string which is well formatted

Example:

Map<String,Object> map = new HashMap<>();
map.put("myNumber", 100);
map.put("myString", "String");

JSONObject json= new JSONObject(map);

String result= json.toString();

System.out.print(result);

result:

{'myNumber':100, 'myString':'String'}

Your can also get key from it like

System.out.print(json.get("myNumber"));

result:

OP wants the opposite of it: HashMap from String! – Harish Feb 14 '19 at 03:36 — Harish, Feb 14 '19 at 03:36

score 2 · Answer 8 · answered May 09 '12 at 11:42

Use StringTokenizer to parse the string.

String s ="SALES:0,SALE_PRODUCTS:1,EXPENSES:2,EXPENSES_ITEMS:3";
    Map<String, Integer> lMap=new HashMap<String, Integer>();


    StringTokenizer st=new StringTokenizer(s, ",");
    while(st.hasMoreTokens())
    {
        String [] array=st.nextToken().split(":");
        lMap.put(array[0], Integer.valueOf(array[1]));
    }

score 1 · Answer 9 · edited May 23 '17 at 11:47

1

You can to use split to do it:

 String[] elements = s.split(",");
 for(String s1: elements) {
     String[] keyValue = s1.split(":");
     myMap.put(keyValue[0], keyValue[1]);
 }

Nevertheless, myself I will go for guava based solution. https://stackoverflow.com/a/10514513/1356883

edited May 23 '17 at 11:47

Community

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answered May 09 '12 at 10:48

kofemann

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score 0 · Answer 10 · answered May 09 '12 at 10:53

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]));
    }

How to convert a string to a HashMap?

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