Java东华理工大学试卷A及答案

东华理工大学2012 —2013 学年第1 学期考试试卷Java程序设计课程闭课程类别：考查A

1 选择题（共35分）

1.What is suffix(后缀) of Java source code？（A）?

A、.java

B、.class

C、.txt

D、.ext

2. Which command can compile Java source code? ( D )?

A、edit

B、dir

C、java

D、javac

3. Which identifies is illegal ( C)?

A、$_$123

B、_something

C、some**name

D、you_can_al

4. Which conversion (转换) is illegal ( B )?注意：byte类型的范围-128-127

A、short x=1000;

B、byte x=1000;

C、byte x=100;

D、float x=12L; 5．class example {

public static void main(String args[]) {

boolean b;

b = (2 > 3) && (3 < 2);

System.out.print("b = "+b);

b = false || true ;

System.out.println("b = "+b); } }

What is the result?( A )

A、b=false b=true

B、b=true b= false

C、b=true b= true

D、b= false b= false

6. class example {

public static void main(String args[]) {

int i=1;

a[i++]=a[i++]+2;

System.out.println(a[i++]);

}} What is the result?( C)

A, 4 B, 5 C 3, D,6 7．public class Example{

String str=new String("good");

char[]ch={'a','b','c'};

public static void main(String args[]){

Example ex=new Example();

ex.change(ex.str,ex.ch);

System.out.print(ex.str+" and ");

Sytem.out.print(ex.ch); }

public void change(String str,char ch[]){

str="test ok";

ch[0]='g'; } } What is the result?( D )

A good and abc

B good and gbc

C test ok and abc

D test ok and gbc

8. Set x=1,y=2,z=3, expression :y+=z--/++x what is result ( A )

A 3

B 3.5

C 4

D 5

9. what is result ( A)?

class example{

static int a=3;

public static void main(String args[]){

new example().a++;

new example().a+=2;

System.out.println(example.a);}}

A 6

B 7

C 4

D 5

10. 1.class X{ ( D)

2.public static void main(String args[]){

3. String s1=new String(“true”);

4. Boolean b1=new Boolean(true);

5. if(s1.equals(b1)){

6. System.out.println(“equal”);}}}

A the program runs and prints nothing

B the program runs and prints “equal”

C An error at line 5 causes compilation to fail

D The program runs but aborts with an exception

11.1.interface A{

2. int a=3;

3. void show();

4.}

5.class B implement A{

6. void show(){}

7.public static void main(String args[]){

8. System.out.println(a++);}}

Which lines are incorrect when the code is compiled?( C )

A 5 7

B 6 8

C 5 6 8

D 5 6

12 class A{

int a=2;}

class B extends A{

int a=3;}

class test{

public static void main(String args[]){

A g=new B(); //不能把子类的东西给父类System.out.println(g.a);}}What is result? ( B)

A 2

B no result

C 1

D 3

13 what is result ( A)

class A{

public static void main(String args[]){

try{

int a=1/0;

int []b={1,2};

b[4]=4; }

catch(ArrayIndexOutOfBoundsException e){

System.out.print("vvv");

}

catch(ArithmeticException e){//算法异常

System.out.print("rrr");

}

finally{

System.out.println("sss");

} } }

A rrrvvv

B rrrsss

C vvvsss

D sssrrr

14. class A{

final int i4=(int)(Math.random()*20);

static final int i5=(int)(Math.random()*20);

public void print(){

System.out.println("i4="+i4+"i5="+i5);}

public static void main(String args[]){

A g1= new A();

g1.print();

A g2= new A();

g2.print(); }}

Assume i4=15 i5=16 when g1.print() method is executed . what result is displayed when g2.print() is executed( A)

A 15 16

B 15 17

C 18 14

D 15 15

15.class A{

void f(int x){System.out.println(x);}

void f(long x){System.out.println(x);}

public static void main(String args[]) {

A g1= new A();

g1.f(5.6); }}

What is result( D )

A 5.6

B 5

C 6

D error

二、翻译题20分，每小题5分

1）Encapsulation（封装）is the mechanism（进程；途径）that binds（约束）together code and the data it manipulates（操纵；操作）, and keep both safe from outside interference（干扰）and misuse（滥用）.

封装是结合在一起的代码和数据处理机制，并保持安全不受外界干扰和误用。2）Encapsulation allows an object to separate its interface from its implementation. The data and the implementation code for the object are hidden behind its interface. So encapsulation hides internal implementation details from users. The power of encapsulated code is that everyone knows how to access it and thus can use it regardless of the implementation details and without fear of unexpected side effects.

封装允许一个对象的接口和实现的分离。该对象的数据和实现代码隐藏在它的接口。所以封装内部实现细节从用户隐藏。封装的代码的能力是每个人都知道如何访问它，从而不论实施细节没有意外的副作用的恐惧使用它。

3）In Java the basis of encapsulation is the class. A class defines the structure and behavior (data and code) that will be shared by a set of objects. Each object of a given class contains the structure and behavior

defined by the class, as if it were stamped out by a mold in the shape of the class. For this reason, objects are sometimes referred to as instance of class. Thus, a class is a logical construct; an object has physical reality.

在Java基础类的封装。一个类定义的结构和行为（数据和代码），将由一组对象的共享。每个对象的一个给定的类包含类定义的结构和行为，就好像它是消灭通过在类形状的模具。因为这个原因，对象有时被称为类的实例。因此，类是一种逻辑结构；对象的物理现实。4）When you create a class, you will specify the code and data that constitute that class. Collectively, these elements are called members of the class. Specifically the code that operates on that data is referred to as member variables or instance variables.

当你创建一个类，你可以指定组成那个类的代码和数据。总的来说，这些元素被称为类的成员。具体操作数据的代码称为成员变量和实例变量。

三程序阅读题(每题4分，共计20分)：

The result of following program is:（2 3 5 7）import java.io.*;

public class UseLabel

{ public static void main(String[] args)

{

Loop:

for(int i=2; i<10; i++)

{ for(int j=2;j

if( i%j == 0) continue Loop;

System.out.print(i+" "); }

}

}

The result of following program is: （124 8）

import java.io.*;

public class Class1 {

public static void main(String args[]){

int i，ax，in；

int a[] = {12,67,8,98,23,56,124,55,99,100);

ax= in= a[0];

for(i=1; i

if( a[i]< in) in = a[i];

if( a[i]> ax) ax = a[i];

}

System.out.println( ax + " " + in); //输出程序在for循环外，后面的程序会覆盖前面输出的程序

System.out.println();

}

}

The result of following program is（a=12

a=1

b=false ch=A）class A

{

int a;

A(){ a=1 ;}

A(int b)

{a=b;}

void show() {

System.out.println(“a=”+a);}

}

public class Class1

{

public static void main (String args[]) {

A a1=new A(12);

A a2=new A();

a1.show();

a2.show();

boolean b=false;

char ch=65;

System.out.println(“b=”+b+”\tch=”+ch);

}

}

The result of following program is: ____x in A:54_____

____x is B:32_______ class A{

int x;

void print(){

System.out.println("x in A:"+x);

}

}

class B extends A{

int x;

void output(){

x=32;

super.x=54;

print();

System.out.println("x is B:"+x);

}

}

public class HideFields {

public static void main(String[] args) {

B b=new B();

b.output();

}

}

The result of following program is:

出现被0除的异常情况

除数=9

被除数=0

java程序运行结束! public class ArithmeticException {

public static void main(String args[]){

int a,b,c;

try{

a=9;

b=0;

c=a/b;

System.out.println(a+"/"+b+"="+c);

}catch(ArithmeticException e){

System.out.println("出现被0除的异常情况");

} finally{

System.out.println("除数="+a);

System.out.println("被除数="+b);

}

System.out.println("java程序运行结束! ");

}

}

四、编程题25分

1．Write a program which cast one integer to byte, one double to int and one double to byte..（10分）

public class test1{

public static void main(String args[]){

int a;

byte b;

byte c;

double a1=9.5;

double b1=8.5;

int c1=2;

a=Integer.parseInt("a1");

b=Byte.parseByte("b1");

c=Byte.parseByte("c1");

System.out.println("a:"+a);

System.out.println("b:"+b);

System.out.println("c:"+c);

}

}

public class test1{

public static void main(String args[]){

char a[]={'1','3','5','8','9'};

for(int i=0;i<4;i++)

{

a[i]=a[i+1];

//System.out.println(a[i]);

}

for(int i=0;i<5;i++)

{

System.out.println(a[i]);

}

}

}