3。B
请查阅JAVA类库。getID方法的返回值是“event type”。在认证考试中，总会有类似的书本以外的知识，这只能靠多实践来增长知识了。
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.
4。A、D
控件可以同时使用多个“addXxxxListener”方法加入多个监听器。并且当多个监听器加入到同一控件中时，事件可以响应多个监听器，响应是没有固定顺序的。
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
5。D、F
本题主要考察考生对流程控制的掌握情况。这是当型循环，条件为真执行，条件为假则退出。循环体至少执行一次，故会输出D。循环体以外的语句总会被执行，故输出F。
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
6。B.C
在开关语句中，标号总是不被当做语句的一部分，标号的作用就是做为条件判断而已，一旦匹配成功，就执行其后的语句，一直遭遇break语句为止。（包括default语句在内）
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
7。D、F
IOException异常类是Exception的子类。根据多态性的定义，IOException对象也可以被认为是Exception类型。还要注意在方法声明中抛出异常应用关键字“throws”。
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
8。D
只有两种情况：大于4时输出“Test1”，小于等于4时输出“Test3”。
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
9。A、C、D
在正常情况下，打印Test1、Test3、Test4；在产生可捕获异常时打印Test2、Test3、Test4；在产生不可捕获异常时，打印Test3，然后终止程序。注意finally后面的语句总是被执行。
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()
10。B
线程的执行是从方法“run( )”开始的，该方法是由系统调用的。程序员手工调用方法start()，使线程变为可运行状态。
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{}
11。A
此题考查内部类及关键字“super”的用法。内部类不能与外部类同名。另外，当Ｂ继承Ａ时，Ａ中的构造函数是带参数的，Ｂ中缺省构造函数的函数体为空；而ＪＡＶＡ编译器会为空构造函数体自动添加语句“super();”调用父类构造函数，更进一步是调用父类的参数为空的构造函数。而父类中没有参数为空的构造函数。
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
12。A
此关键字可以在两个线程同时试图访问某一数据时避免数据毁损。
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
13。C
当一个类中未显式定义构造函数时，缺省的构造函数是以类名为函数名，参数为空，函数体为空。虽然父类中的某一构造函数有字符串参数s，但是子类继承父类时并不继承构造函数，所以它只能使用缺省构造函数。故在第11行出错。
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]
14。A、B
注意，题中问的是如何正确声明一个一维数组，并非实例化或者初始化数组
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…}
15。A、E
X处可以是一个输入，包的定义，类的定义。由于常量或变量的声明只能在类中或方法中，故不能选择C；由于在一个文件中只能有一个public类，故不能选择D。
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
16。B
静态方法除了自己的参数外只能直接访问静态成员。访问非静态成员，必须先实例化本类的一个实例，再用实例名点取。
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
17。A、B、D
polygon的顶点信息存放在Vector类型的对象内部，color定义为Color，length和width定义为int。
注意，这是考试中常见的题型。
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
18。C
此题考点是高级访问控制。请考生查阅高级访问控制说明表格。
责任编辑：小草
您现在的位置： 