更多"现有:   public class&e"的相关试题:
[单项选择] 现有: class Pet implements Serializable { Collar c= new Collar(); } class Collar implements Serializable { collarPart cpl=new CollarPart ("handle"); CollarPart cp2=new CollarPart ("clip"); } class CollarPart implements Serializable() 如果Pet实例被序列化,则多少对象将被序列化?()
A. 0
B. 1
C. 2
D. 3
E. 4
F. 5
[单项选择] public class Pet{ private String name; public Pet(){ System.out.print(1); } public Pet(String name){ System.out.print(2); } } public class Dog extends Pet{ public Dog(String name){ System.out.print(3); } } 执行new Dog(“棕熊”);后程序输出是哪项?()
A. 23
B. 13
C. 123
D. 321
[单项选择] public class Pet{ public void speak(){ System.out.print(“ Pet ”); } } public class Cat extends Pet{ public void speak(){ System.out.print(“ Cat ”); } } public class Dog extends Pet{ public void speak(){ System.out.print(“ Dog ”); } } 执行代码 Pet[] p = {new Cat(),new Dog(),new Pet()}; for(int i=0;i〈p.length;i++) p[i].speak(); 后输出的内容是哪项?()
A. Pet Pet Pet
B. Cat Cat Cat
C. Cat Dog Pet
D. Cat Dog Dog
[单项选择] public class Pet{ private String name; public Pet(){ System.out.print(1); } public Pet(String name){ System.out.print(2); } } public class Dog extends Pet{ public Dog(String name){ //这里隐藏了一句代码:super.pet(); System.out.print(3); } } 执行new Dog(“棕熊”);后程序输出是哪项?()
A. 23
B. 1 3
C. 123
D. 321
[单项选择] public class Pet{} public class Cat extends Pet{} 执行代码 Cat c = new Cat(); Pet p = (Pet)c; 下列哪项是正确的?
A. Pet p = (Pet)c正常执行
B. Pet p = (Pet)c编译错误
C. Pet p = (Pet)c运行错误
D. 以上都不对
[单项选择] 现有 public class Parentt public void change (int x){) ) public class Child extends Parent{ //覆盖父类change方法 } 下列哪个声明是正确的覆盖了父类的change方法?()
A. protected void change (int x){}
B. public void change(int x, int y){}
C. public void change (int x){}
D. public void change (String s){}
[单项选择] 现有: 1 Interface F{} 2 class A implements F{} 3 class B extends A{} 4 class C extends B{ 5 public static void main(String[] args){ 6 B b=new B(); 7 //inSert C0de here 8 } 9 } 下列哪行代码插入到第7行,将抛出java.lang.ClassCaseException异常()
A. A a=b;
B. F f= (C)b;
C. F f= (A)b;
D. B bb= (B)(A)b;
[单项选择] 现有: class Pencil { public void write (String content){ System.out.println ("Write"+content); } } class RubberPencil extends Pencil{ public void erase (String content){ System.out.println ("Erase"+content); } } 执行下列代码的结果是哪项?() Pencil pen=new RubberPencil(); pen.write ("Hello"); pen.erase ("Hello");
A. Write Hello Erase Hello
B. Erase Hello Write Hello
C. 编译错误
D. 运行时抛出异常
[单项选择] 现有: interface I { void go(); } abstract class A implements I { } class C extends A { void go(){ } } 结果是什么?()
A. 代码通过编译
B. 由于第1行的错误导致编译失败
C. 由于笫3行的错误导致编译失败
D. 由于第6行的错误导致编译失败
[单项选择] 现有: class TestA { public void start() { System.out.println("TestA"); } } public class TestB extends TestA { public void start() { System.out.println("TestB"); } public static void main (string[] args) ( ((TestA)new TestB()).start(); ) } 运行结果是哪项?()
A. TeStA
B. TeStB
C. 编译失败
D. 运行时抛出异常
[单项选择] 现有: class Pencil { public void write (String content){ System.out.println( "Write",+content){ } }class RubberPencil extends Pencil{ public void write (String content){ System.out.println("Rubber Write"+content); } public void erase (String content)}} 执行下列代码的结果是哪项?() Pencil pen=new Pencil(); (( RubberPencil) pen).write( "Hello");
A. Write Hello
B. Rubber Write Hello
C. 编译失败
D. 运行时抛出异常
[多项选择] 现有 1. class Calc { 2. public static void main(String [] args) { 3. try { 4. int x = Integer.parselnt ("42a") ; 5. //insert code here 6. System.out.print ("oops"); 7. } 8. } 9. } 下面哪两行分别插入到第五行,会导致输 "oops" ? ()
A. } catch (IllegalArgumentException e) {
B. } catch (IllegalStateException c) {
C. } catch (NumbelFormatException n) {
D. } catch (ClassCastException c) {