Java认证模拟题及分析(2)
添加时间: 2007-9-23 1:14:17 作者: JAVA题库 阅读次数:56 来源: http://www.d9soft.com
Which of the following statements are true?
1) Methods cannot be overriden to be more private
2) Static methods cannot be overloaded
3) Private methods cannot be overloaded
4) An overloaded method cannot throw exceptions not checked in the base class
Answer to Question 16
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Question 17)
What will happen if you attempt to compile and run the following code?
class Base {}
class Sub extends Base {}
class Sub2 extends Base {}
public class CEx{
public static void main(String argv[]){
Base b=new Base();
Sub s=(Sub) b;
}
}
1) Compile and run without error
2) Compile time Exception
3) Runtime Exception
Answer to Question 17
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Question 18)
Which of the following statements are true?
1) System.out.println( -1 >>> 2);will output a result larger than 10
2) System.out.println( -1 >>> 2); will output a positive number
3) System.out.println( 2 >> 1); will output the number 1
4) System.out.println( 1 <<< 2); will output the number 4
Answer to Question 18
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Question 19)
What will happend when you attempt to compile and run the following code?
public class Tux extends Thread{
static String sName = "vandeleur";
public static void main(String argv[]){
Tux t = new Tux();
t.piggy(sName);
System.out.println(sName);
}
public void piggy(String sName){
sName = sName + " wiggy";
start();
}
public void run(){
for(int i=0;i < 4; i++){
sName = sName + " " + i;
}
}
}
1) Compile time error
2) Compilation and output of "vandeleur wiggy"
3) Compilation and output of "vandeleur wiggy 0 1 2 3"
4) Compilation and probably output of "vandeleur" but possible output of "vandeleur 0 1 2 3"
Answer to Question 19
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Question 20)
What will be displayed when you attempt to compile and run the following code
//Code start
import java.awt.*;
public class Butt extends Frame{
public static void main(String argv[]){
Butt MyBut=new Butt();
}
Butt(){
Button HelloBut=new Button("Hello");
Button ByeBut=new Button("Bye");
add(HelloBut);
add(ByeBut);
setSize(300,300);
setVisible(true);
}
}
//Code end
1) Two buttons side by side occupying all of the frame, Hello on the left and Bye on
the right
2) One button occupying the entire frame saying Hello
3) One button occupying the entire frame saying Bye
4) Two buttons at the top of the frame one saying Hello the other saying Bye
Answer to Question 20
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Question 21)
What will be output by the following code?
public class MyFor{
public static void main(String argv[]){
int i;
int j;
outer:
for (i=1;i <3;i++)
inner:
for(j=1; j<3; j++) {
if (j==2)
continue outer;
System.out.println("Value for i=" + i + " Value for j=" +j);
}
}
}
1) Value for i=1 value for j=1
2) Value for i=2 value for j=1
3) Value for i=2 value for j=2
4) Value for i=3 value for j=1
Answer to Question 21
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Question 22)
Which statement is true of the following code?
public class Agg{
public static void main(String argv[]){
Agg a = new Agg();
a.go();
}
public void go(){
DSRoss ds1 = new DSRoss("one");
ds1.start();
}
}
class DSRoss extends Thread{
private String sTname="";
DSRoss(String s){
sTname = s;
}
public void run(){
notwait();
System.out.println("finished");
}
public void notwait(){
while(true){
try{
System.out.println("waiting");
wait();
}catch(InterruptedException ie){}
System.out.println(sTname);
notifyAll();
}
}
}
1) It will cause a compile time error
2) Compilation and output of "waiting"
3) Compilation and output of "waiting" followed by "finished"
4) Runtime error, an exception will be thrown
Answer to Question 22
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Question 23)
Which of the following methods can be legally inserted in place of the comment //Method Here ?
class Base{
public void amethod(int i) { }
}
public class Scope extends Base{
public static void main(String argv[]){
}
//Method Here
}
1) void amethod(int i) throws Exception {}
2) void amethod(long i)throws Exception {}
3) void amethod(long i){}
4) public void amethod(int i) throws Exception {}
Answer to Question 23
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Question 24)
Which of the following will output -4.0
1) System.out.println(Math.floor(-4.7));
2) System.out.println(Math.round(-4.7));
3) System.out.println(Math.ceil(-4.7));
4) System.out.println(Math.min(-4.7));
Answer to Question 24
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Question 25)
What will happen if you attempt to compile and run the following code?
Integer ten=new Integer(10);
Long nine=new Long (9);
System.out.println(ten + nine);
int i=1;
System.out.println(i + ten);
1) 19 followed by 20
2) 19 followed by 11
3) Compile time error
4) 10 followed by 1
Answer to Question 25
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Question 26)
If you run the code below, what gets printed out?
String s=new String("Bicycle");
int iBegin=1;
char iEnd=3;
System.out.println(s.substring(iBegin,iEnd));
1) Bic
2) ic
3) icy
4) error: no method matching substring(int,char)
Answer to Question 26
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Question 27)
If you wanted to find out where the position of the letter v (ie return 2) in the string s
containing " Java ", which of the following could you use?
1) mid(2,s);
2) charAt(2);
3) s.indexOf(´v´);
4) indexOf(s,´v´);
Answer to Question 27
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Question 28)
Given the following declarations
String s1=new String("Hello")
String s2=new String("there");
String s3=new String();
Which of the following are legal operations?
1) s3=s1 + s2;
2) s3=s1-s2;
3) s3=s1 & s2;
4) s3=s1 && s2
Answer to Question 28
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