Write Hello Erase Hello
Erase Hello Write Hello
编译错误
运行时抛出异常
第1题:
现有:classPencil{publicvoidwrite(Stringcontent){System.out.println("Write",+content){}}classRubberPencilextendsPencil{publicvoidwrite(Stringcontent){System.out.println("RubberWrite"+content);}publicvoiderase(Stringcontent)}}执行下列代码的结果是哪项?()Pencilpen=newPencil();((RubberPencil)pen).write("Hello");
A.WriteHello
B.RubberWriteHello
C.编译失败
D.运行时抛出异常
第2题:
interface A{
int x = 0;
}
class B{
int x =1;
}
class C extends B implements A {
public void pX(){
System.out.println(x);
}
public static void main(String[] args) {
new C().pX();
}
}
错误。在编译时会发生错误(错误描述不同的JVM 有不同的信息,意思就是未明确的
x 调用,两个x 都匹配(就象在同时import java.util 和java.sql 两个包时直接声明Date 一样)。
对于父类的变量,可以用super.x 来明确,而接口的属性默认隐含为 public static final.所以可
以通过A.x 来明确。
第3题:
下列程序创建了一个线程并运行,请在下划线处填入正确代码。
public class Try extends Thread{
public static void main(String args[]){
Threadt=new Try();
【 】;
}
public void run(){
System.out.println(“Try!”);
}
}
第4题:
class MyThread extends Thread { public void run() { System.out.println(“AAA”); } public void run(Runnable r) { System.out.println(“BBB”); } public static void main(String[] args) { new Thread(new MyThread()).start(); } } What is the result?()
第5题:
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){ System.out.println ("Erase "+content); } } 执行下列代码的结果是哪项?() Pencil pen=new RubberPencil(); pen.write("Hello");
第6题:
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(); } } What is the result?()
第7题:
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");
第8题:
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?()
第9题:
Write Hello
Rubber Write Hello
编译失败
运行时抛出异常
第10题:
Write Hello
Rubber Write Hello
编译错误
运行时抛出异常
第11题:
TestA
TestB
Compilation fails.
An exception is thrown at runtime.
第12题:
Cause error during compilation.
south east
south to north east to west
south to north east
south east to west
第13题:
现有:classPencil{publicvoidwrite(Stringcontent){System.out.println("Write"+content);}}classRubberPencilextendsPencil{publicvoidwrite(Stringcontent){System.out.println("RubberWrite"+content);}publicvoiderase(Stringcontent){System.out.println("Erase"+content);}}执行下列代码的结果是哪项?()Pencilpen=newRubberPencil();pen.write("Hello");
A.WriteHello
B.RubberWriteHello
C.编译错误
D.运行时抛出异常
第14题:
试题六(共15分)
阅读下列说明和Java代码,将应填入 (n) 处的字句写在答题纸的对应栏内。
【说明】
某发票(lnvoice)由抬头(Head)部分、正文部分和脚注(Foot)部分构成。现采用装饰( Decorator)模式实现打印发票的功能,得到如图6-1所示的类图。
【java代码】
class invoice{
public void printInvoice(){:
System.out.println ( "This is the content of the invoice!");
}
}
class Decorator : extends Invoice {
protected Invoice ticket;
public Decorator(lnvoice t){
ticket = t;
}
public void printinvoice(){
if(ticket != NULL)
(1);
}
}
class FootDecorator extends Decorator{
public FootDecorator(lnvoice t){
super(t);
}
public void printinvoice (){
Systent.out.println( "This is the header of the invoice! ");
(2) ;
}
}
class FootDecorator extends Decorator {
public FootDecorator(invoice t):{
super(t);
}
public void printlnvoice(){
(3) ;
Systent.out.println( "This is the header of the invoice! ");
}
}
Class test {
public static void main(string[] args){
Invoice t =new invioce();
Invoice ticket;
Ticket= (4) ;
Ticket. Printinvoice();
Systent.out.println(“--------------“)
Ticket= (5) ;
Ticket. Printinvoice();
}
}
程序的输出结果为:
This is the header of the invoice!
This is the content of the invoice!
This is the footnote of the invoice!
----------------------------
This is the header of the invoice!
This is the footnote of the invoice!
第15题:
第16题:
class Parent { String one, two; public Parent(String a, String b){ one = a; two = b; } public void print(){ System.out.println(one); } } public class Child extends Parent { public Child(String a, String b){ super(a,b); } public void print(){ System.out.println(one + " to " + two); } public static void main(String arg[]){ Parent p = new Parent("south", "north"); Parent t = new Child("east", "west"); p.print(); t.print(); } } Which of the following is correct?()
第17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18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19题:
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");
第20题:
Write Hello Erase Hello
Erase Hello Write Hello
编译错误
运行时抛出异常
第21题:
第22题:
TeStA
TeStB
编译失败
运行时抛出异常
第23题:
smith,SALES
null,SALES
smith,null
null,null
第24题:
AAA
BBB
Compilation fails.
The code runs with no output.