Jackson for beginners in Eclipse

Question

let me just say that I'm still learning Java and the subtleties of Eclipse, and I come to you because I am unsure how to properly phrase my question to Google or to StackOverflow's search engine. Apologies if its infinitely trivial.

I am trying to understand the process of converting JSON-format strings into objects in Java. I found following example online:

import java.io.IOException;

import org.apache.log4j.Logger;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;public class JsonToJavaConverter {

private static Logger logger = Logger.getLogger(JsonToJavaConverter.class);

public static void main(String args[]) throws JsonParseException,
        JsonMappingException, IOException {

    JsonToJavaConverter converter = new JsonToJavaConverter();

    String json = "{\n" + "    \"name\": \"Garima\",\n"
            + "    \"surname\": \"Joshi\",\n"
            + "    \"phone\": 9832734651}";

    // converting JSON String to Java object
    converter.fromJson(json);
}

public Object fromJson(String json) throws JsonParseException,
        JsonMappingException, IOException {
    User garima = new ObjectMapper().readValue(json, User.class);
    logger.info("Java Object created from JSON String ");
    logger.info("JSON String : " + json);
    logger.info("Java Object : " + garima);

    return garima;
}

public static class User {
    private String name;
    private String surname;
    private long phone;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSurname() {
        return surname;
    }

    public void setSurname(String surname) {
        this.surname = surname;
    }

    public long getPhone() {
        return phone;
    }

    public void setPhone(long phone) {
        this.phone = phone;
    }

    @Override
    public String toString() {
        return "User [name=" + name + ", surname=" + surname + ", phone="
                + phone + "]";
    }
}}

Now, here's the silly part (please don't string me up for asking):

import org.apache.log4j.Logger;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;

Are all underlined in red with Eclipses only hint, being that "The import org.apache.log4j cannot be resolved".

As a newcomer to both Eclipse and Java, this leaves me absolutely dumbstruck.

Could anyone please tell me what needs doing to resolve this basic issue?

Deeply appreciated.

Answer 1

You need to add the libraries (jar files) to the project's build path in Eclipse.

You can find these libraries in Maven Central here:

Log4j

Jackson

Answer 2

You need to add the relevant Jar files to your projects classpath

http://javahowto.blogspot.co.uk/2006/06/set-classpath-in-eclipse-and-netbeans.html