Java Basic(58)-Abstract and Concrete Classes

abstract public class food { →但類必須是abstract的

public abstract void eat(); → 你可以有abstract方法

}

In sub-class:

public class tuna extends food{

public void eat(){ →必須是 public

System.out.println("this tuna is great");

}

}

public class potpie extends food{

public void eat(){ →必須是 public

System.out.println("this potpie is great");

}

}

在子類必須定方法，因為它們是extends從super-class（food）