Sun Java程序员模拟题(4)

} }

执行new Dog(“棕熊”);后程序输出是哪项？ A. 143 B. 423 C. 243 D. 1134

答案： A

３８．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(){

System.out.print(4); }

public Dog(String name){ super(name);

System.out.print(3); } }

执行new Dog(“棕熊”);后程序输出是哪项？ A. 33 B. 13 C. 23 D. 123

答案： C

３９．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); } }

//下段编译错误

public class Manager extends Employee{ private String department;

public Manager(String name,String department){ this.department = department; super(name);

System.out.println(getName()); } }

执行语句new Manager(“smith”,”SALES”)后程序的输出是哪项？ A. smith,SALES B. null,SALES

C. smith,null D. null,null E. 编译错误

答案： A

４０．如果想要一个类不能被任何类继承的话，需要使用哪个关键字来修饰该类？ A. abstract B. final C. static D. new

答案： B

４１．Java语言中常量的定义是哪项？ public static A. public static B. public static final C. final

D. public static abstract

答案： B

４２．为了使得System.out.println()输出对象引用的时候得到有意义的信息，我们应该覆盖Object中的哪个方法？ A. equals B. hashCode C. toString D. notify

答案： C

４３．表达式”hello” instanceof String返回的值是哪项？ 返回true

A. true B. false C. 1 D. 0 E. hello

答案： A

４４．程序： class MyDate{

private int year; private int month; private int day;

public MyDate(int year,int month,int day){

this.year=year;

this.month=month; this.day=day; }

//Override Method }

为了让new MyDate(1980,11,9)==new MyDate(1980,11,9) 返回true，必须在Override Method处覆盖哪个方法？equals A. hashCode B. equals C. toString D. notify

答案： B

４５．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？ A. 京巴 B. 京巴 Dog C. null D. Dog京巴

答案： B

４６．public class Pet{

private static String name; public Pet(String name){ this.name = name; }

public static void speak(){ System.out.print(name); } }