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 { private String name; public Person (String n) { name = n; } public ____________String get Description(); public String getName() { return name; } }
A.private
B.abstract
C.final
D.static
第1题:
下列程序运行后的输出结果是( )。#include#includeusing namespace std;class Person{public:Person(string n):name(n) { cout<<'P'; }private:string name;};class Date{public:Date(int y=2012,int m=12,int d=21):year(y),month(m),day(d) { cout<<'D'; }
private:int year,month,day;};class Student:public Person{public:Student(string n,int y,int m,int d,char c):birthday(y,m,d),sex(c),Person(n) { cout<<'S'; }private:Date birthday;char sex;};int main(){Student stu1("Zhang",1990,10,1,'F');return 0}
A. S
B.PS
C.DPS
D.PDS
第2题:
给出下列的不完整的类代码,则下列的( )语句可以加到横线处。 class Person{ String name,department; int age public Person(String n){name=n;} public Person(String n,int a){name=n;age=a;} pubilc Person(String n,String d,int a) { _______________ department=d; } }
A.Person(n,a);
B.this(Person(n,a));
C.this(n,a);
D.this(name,age);
第3题:
Java代码查错
1.
abstract class Name {
private String name;
public abstract boolean isStupidName(String name) {}
}
大侠们,这有何错误?
错。abstract method 必须以分号结尾,且不带花括号。
第4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5题:
A.public Person(){}
B.public Person(String name,int age) { this.name = name; this.age = age; }
C.public Person(int age,String name) { this.age = age; this.name = name; }
D.public Person(String name) { this.name = name; }
第6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7题:
public class Employee{ private String name; public Employee(String name){ this.name = name; } public String getName(){ return name; } } public class Manager extends Employee{ public Manager(String name){ System.out.println(getName()); } } 执行语句new Manager(“smith”)后程序的输出是哪项?()
第8题:
public class Plant { private String name; public Plant(String name) { this.name = name; } public String getName() { return name; } } public class Tree extends Plant { public void growFruit() { } public void dropLeaves() { } } Which is true?()
第9题:
return super.hashCode();
return name.hashCode() + age * 7;
return name.hashCode() + comment.hashCode() /2;
return name.hashCode() + comment.hashCode() / 2 - age * 3;
第10题:
输出null
第10行编译报错
第11行编译报错
输出Jema
第11题:
The code will compile without changes.
The code will compile if public Tree() { Plant(); } is added to the Tree class.
The code will compile if public Plant() { Tree(); } is added to the Plant class.
The code will compile if public Plant() { this(”fern”); } is added to the Plant class.
The code will compile if public Plant() { Plant(”fern”); } is added to the Plant class.
第12题:
smith,SALES
null,SALES
smith,null
null,null
第13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14题:
给出下面不完整的类代码,则横线处的语句应该为( )。 class Person { String name,department; int age; public Person (Strings) {name=s;} public Person (String s,int
A.{name=s;age=a;} public Person (String n,String d,intA){ __________ department=d; } }A)Person (n,A);
B.this (Person(n,A));
C.this(n,A);
D.this(name,age);
第15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16题:
给出下列的不完整的类代码,则下列的哪个语句可以加到横线处? class Person { String name,department; int age; public Person( String n ){ name = n;} public Person( String n,int a ) { name = n;age = a;} public Person( String n,String d,int a ) { _____________ department = d; } }
A.Person(n,a);
B.this(Person(n,a) );
C.this(n,a);
D.this(name,age);
第17题:
阅读以下说明和Java代码,将应填入(n)处的字句写在对应栏内。
[说明]
在一些大型系统中,大多数的功能在初始化时要花费很多时间,如果在启动的时候,所有功能(连不用的功能)都要全面初始化的话,会连带影响到应用软件要花很多时间才能启动。因此常将程序设计成到了实际要使用某种功能的阶段才初始化该功能。
以下示例展示了Proxy(代理)模式,PrinterProxy类执行一些比较“轻”的方法——设置名称和取得名称,需要真正执行“重”的方法——真正打印——时才初始Print类。图6-1显示了各个类间的关系。
[图6-1]
[Java代码]
//Printable.Java
publiC (1) Printable{
public abstract void setPrinterName(String name);
public abstract String getprinterName();
public abstract void print(String string);
}
//Printer.Java
public class Printer implements Printable{
private String name;
public Printer(){
System.out.println("正在产生Printer的对象实例");
}
public Printer(String name){
this.name=name;
heavyJob("正在产生Printer的对象实例("+name+")");
public void setPrinterName(String name){
this.name=name;
public String getPrinterName(){
return name;
public void print(String string){
System.out.println("===" +name+" ====");
System.out.println(string);
}
}
//PrinterProxy.Java
public class PrinterProxy (2) Printable{
private String name;
private Printer real;
public PrinterProxy(){}
public PrinterProxy(String name){
this.name=name;
}
public gynchronized void setPrinterName(String name){
if( (3) ){
real.setPrinterName(name);
}
this.name=name;
}
public String getprinterName(){
return name;
}
public void print(String string){
(4);
real.print(string);
}
private synchronized void realize(){//产生真正的Printer对象
if(real==null){
real=(5);
}
}
}
(1)
第18题:
public class Person { private String name, comment; private int age; public Person(String n, int a, String c) { name = n; age = a; comment = c; } public boolean equals(Object o) { if(! (o instanceof Person)) return false; Person p = (Person)o; return age == p.age && name.equals(p.name); } } What is the appropriate definition of the hashCode method in class Person?()
第19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?()
第20题:
smith
null
SALES
编译错误
第21题:
smith
null
编译错误
name
第22题:
declare reset() using the synchronized keyword
declare getName() using the synchronized keyword
declare getCount() using the synchronized keyword
declare the constructor using the synchronized keyword
declare increment() using the synchronized keyword
第23题:
Person(n,a);
this(Person(n,a));
this(n,a);
this(name,age);
第24题:
smith
null
SALES
编译错误