Error while compiling a serivce

Hi all,

I am getting the error while creating the service in AEM, as I have created the interface and when I am calling it in my model class it's throwing the error.

package com.aem.demo.core.models;

import javax.annotation.PostConstruct;

import javax.inject.Inject;

import javax.inject.Named;

import com.aem.demo.core.KeyService;

import org.apache.sling.api.resource.Resource;

import org.apache.sling.models.annotations.Default;

import org.apache.sling.models.annotations.Model;

import org.apache.sling.settings.SlingSettingsService;

@Model(adaptables=Resource.class)

public class HelloWorldModel {

@Inject

private KeyService keyService ;

    @Inject

    private SlingSettingsService settings;

    @Inject @Named("sling:resourceType") @Default(values="No resourceType")

    protected String resourceType;

    private String message;

    @PostConstruct

    protected void init() {

   keyService.setKey(80);

        message = "\tHello World!-value of key service is"+keyService.getKey()+"\n";

        message += "\tThis is instance: " + settings.getSlingId() + "\n";

        message += "\tResource type is: " + resourceType + "\n";

    }

    public String getMessage() {

        return message;

    }

}

After compiling the above code

Errors:

[ERROR]   TestHelloWorldModel.setup:49 » NullPointer