Java中实现封装与信息隐藏与抽象与隐藏数据的比较(Practical example Encapsulation vs Information Hiding vs Abstraction vs Data Hiding in Java)

 封装=信息隐藏=数据隐藏。 为了执行某项任务而不需要被他人知道的信息。 
 
class Girl {
  private int age;
  Girl(int age) {
    this.age = age;
  }
  public boolean willGoOutWithGuy(boolean isGuyUgly) {
    return (age >= 22) && (!isGuyUgly);
  }
}

class Guy {
  private Girl girl = new Girl();
  private boolean isUgly = true;
  public boolean willGirlGoOutWithMe() {
    return girl.willGoOutWithGuy(isUgly);
  }
  // Guy doesn't have access to Girl's age. but he can ask her out. 
}
 
 抽象=同一接口的不同实现。 
 
public interface Car {
  public void start();
  public void stop();
}

class HotRod implements Car {
  // implement methods
}

class BattleTank implements Car {
  // implement methods
}

class GoCart implements Car {
  // implement methods
}
 
 这些实现都是唯一的，但可以在Car类型下绑定。 

Encapsulation = information hiding = data hiding. Information that doesn't need to be known to others in order to perform some task.
 
class Girl {
  private int age;
  Girl(int age) {
    this.age = age;
  }
  public boolean willGoOutWithGuy(boolean isGuyUgly) {
    return (age >= 22) && (!isGuyUgly);
  }
}

class Guy {
  private Girl girl = new Girl();
  private boolean isUgly = true;
  public boolean willGirlGoOutWithMe() {
    return girl.willGoOutWithGuy(isUgly);
  }
  // Guy doesn't have access to Girl's age. but he can ask her out. 
}
 
Abstraction = different implementations of the same interface.
 
public interface Car {
  public void start();
  public void stop();
}

class HotRod implements Car {
  // implement methods
}

class BattleTank implements Car {
  // implement methods
}

class GoCart implements Car {
  // implement methods
}
 
The implementations are all unique, but can be bound under the Car type.