文章目錄
在 Java 中,可以将屬性和方法從一個類繼承到另一個類。我們将繼承概念分為兩類:
- ubclass (child) - 從另一個類繼承的類
-
subclass (child) - 繼承自的類
要從類繼承,使用extends 關鍵字。在下面的例子中,Car類(子類)繼承了Vehicle類(超類)的屬性和方法:
class Vehicle {
protected String brand = "Ford";
public void honk() {
System.out.println("Tuut, tuut!");
}
}
class Car extends Vehicle {
private String modelName = "Mustang";
public static void main(String[] args) {
Car myFastCar = new Car();
myFastCar.honk();
System.out.println(myFastCar.brand + " " + myFastCar.modelName);
}
}
運作:
![](https://img.laitimes.com/img/__Qf2AjLwojIjJCLyojI0JCLicmbw5yN3QmYyMGMykTZxMjMiVWO4UWN0UDOlBTOxAzNwcTNi9CX5d2bs92Yl1iclB3bsVmdlR2LcNWaw9CXt92Yu4GZjlGbh5yYjV3Lc9CX6MHc0RHaiojIsJye.png)
如果你不希望其他類繼承自一個類,請使用final關鍵字。
final class Vehicle {
protected String brand = "Ford";
public void honk() {
System.out.println("Tuut, tuut!");
}
}
class Main extends Vehicle {
private String modelName = "Mustang";
public static void main(String[] args) {
Main myFastCar = new Main();
myFastCar.honk();
System.out.println(myFastCar.brand + " " + myFastCar.modelName);
}
}
如果你嘗試通路一個final類,Java 會産生一個錯誤:
Main.java:9: cannot inherit from final Vehicle
class Main extends Vehicle {
^
1 error