再利用性の高いクラス作成に重要な“アクセス制御”

package sample14.app5;
 
class UserInfo {
    private String name;
    private String eMail;
    private boolean member;
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public String getEMail() {
        return eMail;
    }
 
    public void setEMail(String mail) {
        eMail = mail;
    }
 
    public boolean isMember() {
        return member;
    }
 
    public void setMember(boolean member) {
        this.member = member;
    }
}

package sample14.app6;
public class Sample {
    protected String f1;
    private String f2;
}

package sample14.app6;
public class Sample1 extends Sample {
    public void setF1(String f1) {
        this.f1 = f1;
    }
    public String getF1() {
        return f1;
    }
  
    /* f2はprivateフィールドなので使えません
    public void setF2(String f2) {
        this.f2 = f2;
    }
    public String getF2() {
        return f2;
    }
    */
}

package sample14.app6;
public class App {
    public static void main(String[] args) {
        Sample sample = new Sample();
        sample.f1 = "f1";
        System.out.println(sample.f1);
        // sample.f2 = "f2"; // privateなフィールドは使えない
        Sample1 sample1 = new Sample1();
        sample1.f1 = "f1";
        System.out.println(sample1.getF1());
    }
}

package sample14.app7;
import sample14.app6.Sample;
 
public class Sample1 extends Sample {
    public void setF1(String f1) {
        this.f1 = f1;
    }
    public String getF1() {
        return f1;
    }
}

package sample14.app7;
public class App {
    public static void main(String[] args) {
        sample14.app6.Sample sample = new sample14.app6.Sample();
        // sample.f1 = "f1"; // ほかのパッケージ内クラスのprotectedなフィールドは使えない
        Sample1 sample1 = new Sample1();
        System.out.println(sample1.getF1());
    }
}