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java程序员认证笔试试题

时间:2022-08-07 23:29:59 笔试题目 我要投稿
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java程序员认证笔试试题

  以下是CN人才网小编整理的java程序员认证笔试试题,欢迎阅读参考!

java程序员认证笔试试题

  1.Which statement about the garbage collection mechanism are true?

  A. Garbage collection require additional programe code in cases where multiple threads are running.

  B. The programmer can indicate that a reference through a local variable is no longer of interest.

  C. The programmer has a mechanism that explicity and immediately frees the memory used by Java objects.

  D. The garbage collection mechanism can free the memory used by Java Object at explection time.

  E. The garbage collection system never reclaims memory from objects while are still accessible to running user threads.

  2. Give the following method:

  1) public void method( ){

  2) String a,b;

  3) a=new String(“hello world”);

  4) b=new String(“game over”);

  5) System.out.println(a+b+”ok”);

  6) a=null;

  7) a=b;

  8) System.out.println(a);

  9) }

  In the absence of compiler optimization, which is the earliest point the object a refered is definitely elibile to be garbage collection.

  A. before line 3

  B.before line 5

  C. before line 6

  D.before line 7

  E. Before line 9

  3. In the class java.awt.AWTEvent,which is the parent class upon which jdk1.1 awt events are based there is a method called getID which phrase accurately describes the return value of this method?

  A. It is a reference to the object directly affected by the cause of the event.

  B. It is an indication of the nature of the cause of the event.

  C. It is an indication of the position of the mouse when it caused the event.

  D. In the case of a mouse click, it is an indication of the text under the mouse at the time of the event.

  E. It tells the state of certain keys on the keybord at the time of the event.

  F. It is an indication of the time at which the event occurred.

  4. Which statement about listener is true?

  A. Most component allow multiple listeners to be added.

  B. If multiple listener be add to a single component, the event only affected one listener.

  C. Component don?t allow multiple listeners to be add.

  D. The listener mechanism allows you to call an addXxxxListener method as many times as is needed, specifying as many different listeners as your design require.

  5.Give the following code:

  public class Example{

  public static void main(String args[] ){

  int l=0;

  do{

  System.out.println(“Doing it for l is:”+l);

  }while(--l>0)

  System.out.println(“Finish”);

  }

  }

  Which well be output:

  A. Doing it for l is 3

  B. Doing it for l is 1

  C. Doing it for l is 2

  D. Doing it for l is 0

  E. Doing it for l is ?C1

  F. Finish

  6. Give the code fragment:

  1) switch(x){

  2) case 1:System.out.println(“Test 1”);break;

  3) case 2:

  4) case 3:System.out.println(“Test 2”);break;

  5) default:System.out.println(“end”);

  6) }

  which value of x would cause “Test 2” to the output:

  A. 1

  B. 2

  C. 3

  D. default

  7. Give incompleted method:

  1)

  2) { if(unsafe()){//do something…}

  3) else if(safe()){//do the other…}

  4) }

  The method unsafe() well throe an IOException, which completes the method of declaration when added at line one?

  A. public IOException methodName()

  B. public void methodName()

  C. public void methodName() throw IOException

  D. public void methodName() throws IOException

  E. public void methodName() throws Exception

  8. Give the code fragment:

  if(x>4){

  System.out.println(“Test 1”);}

  else if (x>9){

  System.out.println(“Test 2”);}

  else {

  System.out.println(“Test 3”);}

  Which range of value x would produce of output “Test 2”?

  A. x<4

  B. x>4

  C. x>9

  D. None

  9. Give the following method:

  public void example(){

  try{

  unsafe();

  System.out.println(“Test1”);

  }catch(SafeException e){System.out.println(“Test 2”);

  }finally{System.out.println(“Test 3”);}

  System.out.println(“Test 4”);

  Which will display if method unsafe () run normally?

  A. Test 1

  B. Test 2

  C. Test 3

  D. Test 4

  10. Which method you define as the starting point of new thread in a class from which new the thread can be excution?

  A. public void start()

  B. public void run()

  C. public void int()

  D. public static void main(String args[])

  E. public void runnable()

  11.Given the following class definition:

  class A{

  protected int i;

  A(int i){

  this.i=i;

  }

  }

  which of the following would be a valid inner class for this class?

  Select all valid answers:

  A. class B{

  }

  B. class B extends A{

  }

  C. class B extends A{

  B(){System.out.println(“i=”+i);}

  }

  D. class B{

  class A{}

  }

  E. class A{}

  12. Which modifier should be applied to a method for the lock of object this to be obtained prior to excution any of the method body?

  A. synchronized

  B. abstract

  C. final

  D. static

  E. public

  13. The following code is entire contents of a file called Example.java,causes precisely one error during compilation:

  1) class SubClass extends BaseClass{

  2) }

  3) class BaseClass(){

  4) String str;

  5) public BaseClass(){

  6) System.out.println(“ok”);}

  7) public BaseClass(String s){

  8) str=s;}}

  9) public class Example{

  10) public void method(){

  11) SubClass s=new SubClass(“hello”);

  12) BaseClass b=new BaseClass(“world”);

  13) }

  14) }

  Which line would be cause the error?

  A. 9 B. 10 C. 11 D.12

  14. Which statement is correctly declare a variable a which is suitable for refering to an array of 50 string empty object?

  A. String [] a

  B. String a[]

  C. char a[][]

  D. String a[50]

  F. Object a[50]

  15. Give the following java source fragement:

  //point x

  public class Interesting{

  //do something

  }

  Which statement is correctly Java syntax at point x?

  A. import java.awt.*;

  B.package mypackage

  C. static int PI=3.14

  D. public class MyClass{//do other thing…} E. class MyClass{//do something…}

  16. Give this class outline:

  class Example{

  private int x;

  //rest of class body…

  }

  Assuming that x invoked by the code java Example, which statement can made x be directly accessible in main() method of Example.java?

  A. Change private int x to public int x

  B. change private int x to static int x

  C. Change private int x to protected int x

  D. change private int x to final int x

  17. the piece of preliminary analsis work describes a class that will be used frequently in many unrelated parts of a project

  “The polygon object is a drawable, A polygon has vertex information stored in a vector, a color, length and width.”

  Which Data type would be used?

  A. Vector

  B. int

  C. String

  D. Color

  E. Date

  18. A class design requires that a member variable should be accessible only by same package, which modifer word should be used?

  A. protected

  B. public

  C. no modifer

  D. private

  19.Which declares for native method in a java class corrected?

  A. public native void method(){}

  B. public native void method();

  C. public native method();

  D. public void method(){native;}

  E. public void native method();

  20. Which modifer should be applied to a declaration of a class member variable for the value of variable to remain constant after the creation of the object?

  21. Which is the main() method return of a application?

  A. String

  B. byte

  C. char

  D. void

  22. Which is corrected argument of main() method of application?

  A. String args

  B. String ar[]

  C. Char args[][]

  D. StringBuffer arg[]

  23. “The Employee object is a person, An Employee has appointment store in a vector, a hire date and a number of dependent”

  short answer: use shortest statement declare a class of Employee.

  24. Give the following class defination inseparate source files:

  public class Example{

  public Example(){//do something}

  protected Example(int i){//do something}

  protected void method(){//do something}

  }

  public class Hello extends Example{//member method and member variable}

  Which methods are corrected added to the class Hello?

  A. public void Example(){}

  B. public void method(){}

  C. protected void method(){}

  D. private void method(){}

  25. Float s=new Float(0.9F);

  Float t=new Float(0.9F);

  Double u=new Double(0.9);

  Which expression?s result is true?

  A. s==t

  B. s.equals(t)

  C. s==u

  D. t.equals(u)

  26. Give following class:

  class AClass{

  private long val;

  public AClass(long v){val=v;}

  public static void main(String args[]){

  AClass x=new AClass(10L);

  AClass y=new AClass(10L);

  AClass z=y;

  long a=10L;

  int b=10;

  }

  }

  Which expression result is true?

  A. a==b;

  B. a==x;

  C. y==z;

  D. x==y;

  E. a==10.0;

  推荐阅读

  Java认证的目的

  美国Sun公司提供的关于Java的SCJP/SCJD认证是全球各大企业都认同的行业认证之一,其特点是培训和考试费用高、考试难度较大。那么,为何要进行Java的认证考试呢?其目的主要为:

  Java认证是全球各大企业都认可的行业认证,获取该认证表明您有很高水平的Java编程能力,这样就可以拥有更多的找到好的满意的工作的机会,当然,这也同样为您的提升增加了一个很重要的砝码。

  Java语言本身很简单,很容易学和使用,但也有很多的一些习惯用法与其它语言不同。获得JSCP认证将使您在Java编程中更具有专业性,同时也能极大地增强您的自信心。

  使用Java语言可以编写简短、精确、清晰的一流的程序,但是其认证却是比较困难的考试,不过这却让SCJP考试具有更高的价值。

  目前有很多要出国或者移民的人参加该项培训和认证,因为在美国或加拿大,Java编程的需求是非常大的。

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