Convert Java Map to Javascript Map

Question

I have a Java Map. I want to convert it in to JavaScript map.

The java function to convert as JS map follows:

private Object getJSLocalizedValueMap() {

    Map<String, String> langSel = new HashMap<String, String>();
    langSel.add("en", true);
    langSel.add("de", false);
    langSel.add("fr", false);

    //Now convert this map into Javascript Map
    NativeObject nobj = new NativeObject();
    ScriptEngineManager factory = new ScriptEngineManager();
    ScriptEngine engine = factory.getEngineByName("javascript");
    for (Map.Entry<String, String> entry : langSel.entrySet()) {
        nobj.defineProperty(entry.getKey(), entry.getValue(), NativeObject.READONLY);
    }
    engine.put("langSel", nobj);
    return langSel;
}

In the JSP page's javascript the code is:

var langs = ${messagesJS};

In Javascript, I got:

langs = {en=true, de=false, fr=false};

instead of

langs = {"en":true, "de":false, "fr":false}

Please suggest me how to achieve this?

Is there any reason you need to have the keys wrapped in double quotes? You already have a valid JavaScript object. If it's an absolute requirement (and, again, I can't think of a single reason why it would be), take a look at returning JSON. — Anthony Grist
– Anthony Grist, Commented Dec 12, 2012 at 13:23

cowls · Accepted Answer · 2012-12-17 11:12:14Z

5

You might be able to use the JSONObject class for this. It has a constructor that you pass in a Map. Call that and then call the toString() method and it should give you a JS array.

http://www.json.org/javadoc/org/json/JSONObject.html#JSONObject%28java.util.Map%29

So something like:

Map<String, String> langSel = new HashMap<String, String>();
langSel.add("en", true);
langSel.add("de", false);
langSel.add("fr", false);

JSONObject jsonObj = new JSONObject(langSel);
engine.put("langSel", jsonObj.toString());

You will need to make sure the org.json.JSONObject class is on your classpath. Either download the JAR and add to classpath manually (through Eclipse or something) or if you are using Maven use a dependency like the following:

  <dependency>
    <groupId>org.json</groupId>
    <artifactId>json</artifactId>
    <version>20070829</version>
  </dependency>

If you are not using Maven, you can still download the JAR from here: http://mvnrepository.com/artifact/org.json/json/20090211

edited Dec 17, 2012 at 11:12

answered Dec 12, 2012 at 13:21

cowls

24.4k9 gold badges51 silver badges78 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Rajasekhar Over a year ago

How to get the JSONObject class. It is giving class path not found.

Rajasekhar Over a year ago

Thanks cowls, I am able to add in the class path. But, still I am getting the string as {en=true, de=false, fr=false} (JSP map) instead of {"en":true, "de":false, "fr":false} (javaScript map) in JSP page.

cowls Over a year ago

I would need to see the code. Make sure you are not still returning langSel, as this is a java Map and will give that output, you should be returning the json object

Rajasekhar Over a year ago

Thanks cowls, Its working fine. Acutually, I created a JSONObject by new JSONObject() function and then added each map entry to jsonObj by converting the second string to Boolean. Now, It is working fine. Thank you.

NPKR · Accepted Answer · 2012-12-12 13:28:22Z

2

Instead of below line

langSel.add("en", true);

use this line

langSel.add("\"en\"", true);

Try this it might helpful.

answered Dec 12, 2012 at 13:28

NPKR

5,5265 gold badges35 silver badges48 bronze badges

Collectives™ on Stack Overflow

Convert Java Map to Javascript Map

2 Answers 2

4 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related