cannot convert from String to HashMap Spring Boot application

Question

I have below code and issue. I am running a Spring boot application to test application.properties file usage.

application.properties file,

server.port=8080
server.servlet.context-path=/HelloWorldBoot

myMap={key1:'value1',key2:'value2'}

Controller code below,

@RestController
public class MyController {

    @Autowired
    Environment env;

    @Value("#{${myMap}}")  
    private HashMap<String,String> myMapUsingValue;

    @GetMapping("/hello")
    public String hello() {
        System.out.println("myMapUsingValue : "+myMapUsingValue);

        HashMap<String, String> myMapUsingEnv = env.getProperty("myMap", HashMap.class);
        System.out.println("myMapUsingEnv : "+myMapUsingEnv);

        return "Hello World";
    }
}

Now when I hit the URL: http://localhost:8080/HelloWorldBoot/hello

Map details using @Value gets printed successfully,

myMapUsingValue : {key1=value1, key2=value2}

But I get error like below while accessing the same Map using Environment API,

No converter found capable of converting from type [java.lang.String] to type [java.util.HashMap<?, ?>]]

How can I resolve this? How can I read the Map directly from application properties file using the Environment variable API?

Any help is appreciated on this. Thanks in advance.

Try using the interface Map not the implementation HashMap — akuma8
– akuma8, Commented Aug 24, 2018 at 14:03

Robert Moskal · Accepted Answer · 2018-08-24 17:56:11Z

2

Environment variables are always strings. The fact that the Spring value injector knows how to convert them to a map is super nice, but when using the java environment api you are going to have to parse that string yourself and convert it into a Map.

Something like Jackson might make this easier. Otherwise you might write a utility method that does this. You might look in the spring source.

edited Aug 24, 2018 at 17:56

answered Aug 24, 2018 at 14:18

Robert Moskal

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1 Comment

WebNoob Over a year ago

Thanks for the details. It seems that there is no straight cut way to get a map out of environment API. I had to take that string, then remove curly braces, then remove apostrophe sign and then split the string to fetch out key-value pairs and then put them in map. Whoo... Thanks for suggestions.

James Siva · Accepted Answer · 2019-06-25 06:48:39Z

-1

Don't think too much just check your pojo class. Getting value from database is different , field from pojo class is different.

answered Jun 25, 2019 at 6:48

James Siva

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