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A1 选择题（共35分）1.What is suffix(后缀) of Java source code？（A）?A、.javaB、.classC、.txtD、.ext2. Which command can compile Java source code? ( D )?A、editB、dirC、javaD、javac3. Which identifies is illegal ( C)?A、$_$123B、_somethingC、some**nameD、you_can_al4. Which conversion (转换) is illegal ( B )?注意：byte类型的范围-128-127A、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=trueB、b=true b= falseC、b=true b= trueD、b= false b= false6. 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 abcB good and gbcC test ok and abcD test ok and gbc8. Set x=1,y=2,z=3, expression :y+=z--/++x what is result ( A )A 3B 3.5C 4D 59. 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 6B 7C 4D 510. 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 nothingB the program runs and prints “equal”C An error at line 5 causes compilation to failD The program runs but aborts with an exception11.1.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 7B 6 8C 5 6 8D 5 612 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 2B no resultC 1D 313 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 rrrvvvB rrrsssC vvvsssD sssrrr14. 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 16B 15 17C 18 14D 15 1515.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 5.6B 5C 6D 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 behaviordefined 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。