# Super 程序題 **題目一** ~~~ class Base{ Base(){ System.out.println("Base"); } } public class Checket extends Base{ Checket(){ System.out.println("Checket"); super(); } public static void main(String argv[]){ Checket a = new Checket(); } } ~~~ 輸出是什么？ 是 compile time error. super() 必須放在前面. 放在前面之后,輸出為 Base Checket **題目二** ~~~ import java.util.Date; public class Test extends Date{ public static void main(String[] args) { new Test().test(); } public void test(){ System.out.println(super.getClass().getName()); } } ~~~ 返回的結果是 Test 因為super.getClass().getName() 調用了父類的 getClass() 方法, 返回當前類 如果想得到父類的名稱，應該用如下代碼： ~~~ getClass().getSuperClass().getName() ~~~ **題目三** ~~~ public abstract class Car { String name = "Car"; public String getName(){ return name; } public abstract void demarre(); } public class B extends Car{ String name = "B"; public String getName(){ return name; } public void demarre() { System.out.println(getName() + " demarre"); } } public class C extends B{ String name = "C"; public String getName(){ return name; } public void demarreWithSuper() { System.out.println(super.getName() + " demarre"); } public void demarreNoSuper() { System.out.println(getName() + " demarre"); } } public class D extends B{ public String getName(){ return name; } public void demarreNoSuper() { System.out.println(getName() + " demarre"); } } public class Test { public static void main(String[] args) { B b = new B(); b.demarre(); Car bCar = new B(); bCar.demarre(); C c = new C(); c.demarre(); // c 里并沒有定義這個函數 c.demarreWithSuper(); c.demarreNoSuper(); D d = new D(); d.demarre(); transfer(c); // TransferC transfer((B)c); // TransferB transfer(d); // TransferB } public static void transfer(B b){ System.out.println("TransferB"); b.demarre(); } public static void transfer(C c){ System.out.println("TransferC"); c.demarre(); } } } ~~~ 輸出是B demarreB demarreC demarreB demarreC demarreB demarreTransferCC demarreTransferBC demarreTransferBB demarre