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BaseClass.java
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140 lines (114 loc) · 2.89 KB
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package class_ex;
/**
* Class 和 Object 物件
*
* 訊息是唯一可令物件執行操作的管道, 操作則是唯一可改變物件內部狀態的管道。
* 有了這些限制, 物件內部狀態可說是被妥為封裝了起來 (encapsulation) :
* 無法接觸及, 無法自外界窺伺。
*
*
* TODO: use super().
*
* 你可以抽象化interface, abstract, or concrete class.
*
* References:
* - https://pdai.tech/md/java/basic/java-basic-oop.html
* - https://nwpie.blogspot.com/2017/05/3-class-interface-abstract.html
*/
interface OriginInterface {
// interface class.
static String name = "OriginInterface";
public void printSelf();
public void printHello();
private void printName() {
System.out.println("name: " + name);
}
}
abstract class Origin implements OriginInterface {
// abtstact class.
public void printHello() {
System.out.println("Hello by Origin.");
}
}
class HH extends Origin {
// concorete class.
@Override
public void printSelf() {
System.out.println("HH");
}
// ! HH 的 printHello() 已繼承了 Origin
}
class AA extends Origin {
// concorete class.
@Override
public void printSelf() {
System.out.println("AA");
}
@Override
public void printHello() {
System.out.println("Hello by AA.");
}
}
/**
* 你可以建立新的class去繼承，不改寫父類別原有方法則。
*/
class BB extends AA {
// concorete class.
@Override
public void printSelf() {
System.out.println("BB");
}
// ! BB 的 printHello() 已繼承了 AA
}
/**
* 覆寫(Override)是指子類別繼承父類別時，改寫父類別原有的方法內容
*/
class CC extends AA {
// concorete class.
@Override
public void printSelf() {
System.out.println("CC");
}
@Override
public void printHello() {
System.out.println("Hello by CC.");
}
}
public class BaseClass {
public static void main(String[] args) {
// B b = new B();
// b.printA();
AA a = new AA();
a.printSelf();
a.printHello();
BB b = new BB();
b.printSelf();
b.printHello();
CC c = new CC();
c.printSelf();
c.printHello();
DD d = new DD();
// 注意會擋非 OriginInterface & OriginInterface子類別
// showInfo(d); //! error!!
showInfo(c);
HH h = new HH();
h.printSelf();
h.printHello();
showInfo(h);
}
public static void showInfo(OriginInterface oi) {
// ! 統一開啟一個 function: get printSelf() 值
oi.printSelf();
}
}
/**
* 可使用 final 關鍵字來讓class不允許繼承
*/
final class DD {
public void printSelf() {
System.out.println("DD");
}
}
// ! 會有錯誤，因為 DD 不允許被繼承。
// class EE extends DD {
// }