smith
null
SALES
编译错误
第1题:
阅读下面代码 abstract class Person { public Person(String n) { name=n; } public______String getDescription(); public String getName() { return name; } private String name; } 在下画线处应填入的修饰符是
A.static
B.abstract
C.protected
D.final
第2题:
为使下列代码正常运行,应该在下画线处填入的选项是( )。 abstract class person{ public Person(String n){ name=n: } Public String getDescription; public String getName{ return name; } private string name; }
A.static
B.private
C.abstract
D.final
第3题:
为使下列代码正常运行,应该在下划线处填入的选项是
abstract class Person{
public Person(String n)!
name=n;
}
public____String getDescription();
public String getName(){
return name;
}
private String name;
}
A.static
B.private
C.abstract
D.final
第4题:
public class Pet{ private String name; public Pet(String name){ this.name = name; } public void speak(){ System.out.print(name); } } public class Dog extends Pet{ public Dog(String name){ super(name); } public void speak(){ super.speak(); System.out.print(“ Dog ”); } } 执行代码 Pet pet = new Dog(“京巴”); pet.speak(); 后输出的内容是哪项?()
第5题:
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?()
第6题:
interface Playable {
void play();
}
interface Bounceable {
void play();
}
interface Rollable extends Playable, Bounceable {
Ball ball = new Ball("PingPang");
}
class Ball implements Rollable {
private String name;
public String getName() {
return name;
}
public Ball(String name) {
this.name = name;
}
public void play() {
ball = new Ball("Football");
System.out.println(ball.getName());
}
}
这个错误不容易发现。
错。"interface Rollable extends Playable, Bounceable"没有问题。interface 可继承多个
interfaces,所以这里没错。问题出在interface Rollable 里的"Ball ball = new Ball("PingPang");"。
任何在interface 里声明的interface variable (接口变量,也可称成员变量),默认为public static
final。也就是说"Ball ball = new Ball("PingPang");"实际上是"public static final Ball ball = new
Ball("PingPang");"。在Ball 类的Play()方法中,"ball = new Ball("Football");"改变了ball 的
reference,而这里的ball 来自Rollable interface,Rollable interface 里的ball 是public static final
的,final 的object 是不能被改变reference 的。因此编译器将在"ball = new Ball("Football");"
这里显示有错。
第7题:
执行以下代码后,下面哪些描述是正确的() public class Student{ private String name = “Jema”; public void setName(String name){ this.name = name; } public String getName(){ return this.name; } public static void main(String[] args){ Student s; System.out.println(s.getName()); } }
第8题:
阅读下列代码段 abstract class Person{ public Person(String n){ name=n; } public______String getDescription(); public String getName(){ } private String name; } 在下画线处应填入的修饰符是
A.static
B.abstract
C.protected
D.final
第9题:
public class Employee{ private String name; public Employee(String name){ this.name = name; } public String getName(){ return name; } } public class Manager extends Employee{ private String department; public Manager(String name,String department){ this.department = department; super(name); (应于上一行掉位置) System.out.println(getName()); } } Super的位置是否在方法的首行 执行语句new Manager(“smith”,”SALES”)后程序的输出是哪项?()
第10题:
public class Employee{ private String name; public Employee(String name){ this.name = name; } public void display(){ System.out.print(name); } } public class Manager extends Employee{ private String department; public Manager(String name,String department){ super(name); this.department = department; } public void display(){ System.out.println(super.display()+”,”+department); } } 执行语句new Manager(“smith”,”SALES”)后程序的输出是哪项?()