Inheritance or composition article

Automobile.java

package com.leonardorifeli.article.inheritance.model;

public class Automobile {

    private String color;
    private Integer quantityPort;

    public String getColor() {
        return color;
    }

    public void setColor(String color) {
        this.color = color;
    }

    public Integer getQuantityPort() {
        return quantityPort;
    }

    public void setQuantityPort(Integer quantityPort) {
        this.quantityPort = quantityPort;
    }
}

Car.java

package com.leonardorifeli.article.inheritance.model;

public class Car extends Automobile {

    public Car(final String color, final Integer quantityPort) {
        this.setColor(color);
        this.setQuantityPort(quantityPort);
    }

    public String getColor() {
        return "perfect "+ this.color;
    }

    public String myColor() {
        return "Color is: "+ this.getColor();
    }

    public String myQuantityPort() {
        return "Quantity port is: "+ this.getQuantityPort();
    }

}

Job.java

package com.leonardorifeli.article.composition.model;

public class Job {

    private String name;
    private String service;
    private boolean started = false;

    public Job(final String name, final String service, final boolean started) {
        this.name = name;
        this.service = service;
        this.started = started;
    }

    public String checkAndStartJob() {
        if(this.started == true) {
            return "Job has already started.";
        }

        if(this.started == false) {
            this.startJob();
            return "Job is started";
        }

        return "Job stoped";
    }

    private void startJob() {
        this.started = true;
    }

    private void stopJob() {
        this.started = false;
    }

}

People.java

package com.leonardorifeli.article.composition.model;

public class People {

    private String name;
    private boolean hasJob;

    public People(final String name, final boolean hasJob) {
        this.name = name;
        this.hasJob = hasJob;

        if(this.hasJob == true) {
            Job job = new Job(this.name, "Developer", true);

            job.checkAndStartJob();
        }
    }

}

String.java

package com.leonardorifeli.article.inheritance.model;

public class String {

    @Override
    public String toString() {
        return "Is a new string";
    }

}