SCJP试题－SCJPMockExam4

Question 1)
Which of the following lines will compile without warning or error. 

1) float f=1.3; 
2) char c="a"; 
3) byte b=257; 
4) boolean b=null; 
5) int i=10; 


Answer to Question 1 


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Question 2)
What will happen if you try to compile and run the following code 

public class MyClass {
public static void main(String arguments[]) {
amethod(arguments);
}
public void amethod(String[] arguments) {
System.out.println(arguments);
System.out.println(arguments[1]);
}
}
1) error Can’t make static reference to void amethod. 
2) error method main not correct 
3) error array must include parameter 
4) amethod must be declared with String 

Answer to Question 2 


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Question 3)
Which of the following will compile without error 

1) 

import java.awt.*;
package Mypackage;
class Myclass {}
2) 

package MyPackage;
import java.awt.*;
class MyClass{}
3) 

/*This is a comment */

package MyPackage;
import java.awt.*;
class MyClass{}

Answer to Question 3 


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Question 4)
A byte can be of what size 

1) -128 to 127 
2) (-2 power 8 )-1 to 2 power 8 
3) -255 to 256 
4)depends on the particular implementation of the Java Virtual machine 

Answer to Question 4 


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Question 5)
What will be printed out if this code is run with the following command line? 

java myprog good morning
public class myprog{
public static void main(String argv[])
{
System.out.println(argv[2])
}
}
1) myprog 
2) good 
3) morning 
4) Exception raised: "java.lang.ArrayIndexOutOfBoundsException: 2" 


Answer to Question 5 


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Question 6)
Which of the following are keywords or reserved words in Java? 

1) if 
2) then 
3) goto 
4) while 
5) case 

Answer to Question 6 


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Question 7)
Which of the following are legal identifiers 

1) 2variable 
2) variable2 
3) _whatavariable 
4) _3_ 
5) $anothervar 
6) #myvar 

Answer to Question 7 


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Question 8)
What will happen when you compile and run the following code? 


public class MyClass{
static int i;
public static void main(String argv[]){
System.out.println(i);
}
}
1) Error Variable i may not have been initialized 
2) null 
3) 1 
4) 0 

Answer to Question 8 


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Question 9)
What will happen if you try to compile and run the following code? 

public class Q {
public static void main(String argv[]){
int anar[]=new int[]{1,2,3};
System.out.println(anar[1]);
}
}
1) 1 
2) Error anar is referenced before it is initialized 
3) 2 
4) Error: size of array must be defined 


Answer to Question 9 


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Question 10)

What will happen if you try to compile and run the following code? 

public class Q {
public static void main(String argv[]){
int anar[]=new int[5];
System.out.println(anar[0]);
}
}
1) Error: anar is referenced before it is initialized 
2) null 
3) 0 
4) 5 

Answer to Question 10 


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Question 11)

What will be the result of attempting to compile and run the following code? 

abstract class MineBase {
abstract void amethod();
static int i;
}
public class Mine extends MineBase {
public static void main(String argv[]){
int[] ar=new int[5];
for(i=0;i < ar.length;i++)
System.out.println(ar[i]);
}
}
1) a sequence of 5 0’s will be printed 
2) Error: ar is used before it is initialized 
3) Error Mine must be declared abstract 
4) IndexOutOfBoundes Error 

Answer to Question 11  




Question 12)
What will be printed out if you attempt to compile and run the following code ? 

int i=1;
switch (i) {
case 0:
System.out.println("zero");
break;
case 1:
System.out.println("one");
case 2:
System.out.println("two");
default:
System.out.println("default");
}
1) one 
2) one, default 
3) one, two, default 
4) default 

Answer to Question 12 


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Question 13)
What will be printed out if you attempt to compile and run the following code? 

int i=9;
switch (i) {
default:
System.out.println("default");
case 0:
System.out.println("zero");
break;
case 1:
System.out.println("one");
case 2:
System.out.println("two");
}
1) default 
2) default, zero 
3) error default clause not defined 
4) no output displayed 

Answer to Question 13 


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Question 14)
Which of the following lines of code will compile without error 

1) 

int i=0;
if(i) {
System.out.println("Hello");
}
2) 

boolean b=true;
boolean b2=true;
if(b==b2) {
System.out.println("So true");
}
3) 

int i=1;
int j=2;
if(i==1|| j==2)
System.out.println("OK");
4) 

int i=1;
int j=2;
if(i==1 &| j==2)

System.out.println("OK");
Answer to Question 14 


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Question 15)
What will be output if you try to compile and run the following code, but there is 
no file called Hello.txt in the current directory?. 

import java.io.*;
public class Mine {
public static void main(String argv[]){
Mine m=new Mine();
System.out.println(m.amethod());
}
public int amethod() {
try {
FileInputStream dis=new FileInputStream("Hello.txt");
}catch (FileNotFoundException fne) {
System.out.println("No such file found");
return -1;
}catch(IOException ioe) {
} finally{
System.out.println("Doing finally");
}

return 0;
}

}
1) No such file found 
2 No such file found ,-1 
3) No such file found, Doing finally, -1 
4) 0 

Answer to Question 15 


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Question 16)
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 exc