scjp试题－scjpmockexam4.txt

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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 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 "vandelur" 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