ObjectMapper cannot be resolved to a type

Question

I have troubles getting JSON to work. ObjectMapper cannot be resolved. Library is imported correctly.

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import net.sf.json.JSONException;
import net.sf.json.util.*;

import com.fasterxml.jackson.*;

public class Json {
    private static final String jsonFilePath = "C:\\Users\\Juergen\\Desktop\\filesForExamples\\mapExample.json";

    public static void objectToJSON(HashMap<String, Mat> map) {
        //Map<String, Object> mapObject = new HashMap<String, Object>();
        ObjectMapper mapper = new ObjectMapper();

        try {
            objectMapper.writeValue(new File(jsonFilePath), map);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

If Eclipse has something like a "quick fix", then it would could suggest an import. But I don't know if it has such a feature. But anyway, this problem is the missing import, so you could delete this question, because it won't help future readers and asking, why Eclipse doesn't suggest an import before noting the error, is quite off-topic :P. — Tom, Dec 15 '15 at 13:53
This is maybe something what you're looking for: https://wiki.eclipse.org/FAQ_What_is_a_Quick_Fix%3F — Tom, Dec 15 '15 at 13:56
i found out that i need to import the jackson package additionally. i downloaded it. But how do i get the full path to know for a correct package import? — Jürgen K., Dec 15 '15 at 14:07
Depends on your version. Check the JavaDoc of your version or use Ctrl+Space for auto completion. Eclipse should then show available classes for import. — Tom, Dec 15 '15 at 14:12
You don't need the JavaDoc in the jar, since it should be available on the internet :P. — Tom, Dec 15 '15 at 14:19
what has any javadoc to do with the downloaded package name?sorry i'm not sure what you mean — Jürgen K., Dec 15 '15 at 14:20
if u want to auto import needed objects in eclipse, use the shortcut ctrl + shift + o.. — lunatikz, Dec 15 '15 at 14:24
if u just downloaded Jackson as jar file, dont forget to add it to your buildpath — lunatikz, Dec 15 '15 at 14:25
did u refreshed your project ? (if you just copied the jar file in a folder like /lib inside your project, eclipse wont recognize, until you refresh) and maybe should clean and recompile.. — lunatikz, Dec 15 '15 at 14:34
refreshed!But the jackson packages doesn't contain "databind" — Jürgen K., Dec 15 '15 at 14:36
and make sure, that you have the jar file "..jackson-databind..", for using ObjectMapper .. — lunatikz, Dec 15 '15 at 14:36
yeah there are several packages of jackson, for using ObjectMapper u need to get jackson-databind. So you have for jackson atleast 2 jar files.. jackson-core and jackson-databind — lunatikz, Dec 15 '15 at 14:37
it's a shame that for serialization of generics you need 3 packages — Jürgen K., Dec 15 '15 at 14:43

score 14 · Answer 1 · edited Mar 22 '21 at 17:10

If you are using **maven** project then add the following in the `POM.xml`

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.12.1</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>2.12.1</version>
</dependency>
    
But if you are using a **simple java** project then you need to add the following jars in your class path:
    
    jackson-core-2.1.X,
    jackson-databind-2.1.X

score 9 · Answer 2 · answered Mar 08 '19 at 11:44

9

Add import com.fasterxml.jackson.databind.ObjectMapper; to your project.

answered Mar 08 '19 at 11:44

Vishwa Ratna

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ObjectMapper cannot be resolved to a type

2 Answers2