SCJP 1.4 Mock Questions on Basic JAVA
Question 1
class GRC7 {public void main(String[] args) {}} // 1
class GRC8 {public void main(String []args) {}} // 2
class GRC9 {public void main(String args[]) {}} // 3
What is the result of attempting to compile and run the above programs?
a. Compile-time error at line 1.
b. Compile-time error at line 2.
c. Compile-time error at line 3.
d. An attempt to run GRC7 from the command line fails.
e. An attempt to run GRC8 from the command line fails.
f. An attempt to run GRC9 from the command line fails.
Question 2
class MCZ29 {
public static void main (String[] args) {
char a = '\a'; // 1
char b = '\b'; // 2
char c = '\f'; // 3
char d = '\n'; // 4
char e = '\r'; // 5
}}
A compile-time error is generated at which line?
a. 1
b. 2
c. 3
d. 4
e. 5
f. None of the above
Question 3
class MCZ30 {
public static void main (String[] args) {
char a = '\t'; // 1
char b = '\\'; // 2
char c = '\?'; // 3
char d = '\"'; // 4
char e = '\''; // 5
}}
A compile-time error is generated at which line?
a. 1
b. 2
c. 3
d. 4
e. 5
f. None of the above
Question 4
Which of these words belongs to the set of Java keywords?
a. qualified
b. record
c. repeat
d. restricted
e. label
f. to
g. type
h. until
i. value
j. virtual
k. xor
l. None of the above
Question 5
class MCZ31 {
public static void main (String[] args) {
char a = '\t'; // 1
char b = '\\'; // 2
char c = '\"'; // 3
char d = '\''; // 4
char e = '\?'; // 5
}}
A compile-time error is generated at which line?
a. 1
b. 2
c. 3
d. 4
e. 5
f. None of the above
Question 6
Which of these words belong to the set of Java keywords?
a. exit
b. strictfp
c. enum
d. super
e. abort
f. event
g. goto
h. native
i. exception
Question 7
class MCZ13 {
public static void main (String[] args) {
String s = null;
System.out.print(s);
}}
What is the result of attempting to compile and run the program?
a. Prints nothing.
b. Prints: null
c. Compile-time error
d. Run-time error
e. None of the above
Question 8
class MWC103 {
public static void main(String[] args) {
int[] a1 = {1,2,3};
int []a2 = {4,5,6};
int a3[] = {7,8,9};
System.out.print(a1[1]+","+a2[1]+","+a3[1]);
}}
What is the result of attempting to compile and run the program?
a. Prints: 12
b. Prints: 15
c. Prints: 18
d. Prints: 1,4,7
e. Prints: 2,5,8
f. Prints: 3,6,9
g. Compile-time error
h. Run-time error
i. None of the above
Question 9
class JJF4 {
public static void main(String args[]) {
System.out.print(Long.toHexString(Byte.MAX_VALUE)+",");
System.out.print(Long.toHexString(Character.MAX_VALUE)+",");
System.out.print(Long.toHexString(Short.MAX_VALUE));
}}
What is the result of attempting to compile and run the program?
a. Prints: f,ff,7f
b. Prints: f,ff,ff
c. Prints: 7f,ffff,7fff
d. Prints: ff,ffff,ffff
e. Prints: 7fff,ffffff,7fffff
f. Prints: ffff,ffffff,ffffff
g. Compile-time error
h. Run-time error
i. None of the above
Question 10
class MWC104 {
public static void main(String[] args) {
int[5] a1; // 1
int []a2; // 2
int[ ]a3; // 3
int a4[]; // 4
}}
A compile-time error is generated at which line?
a. 1
b. 2
c. 3
d. 4
e. None of the above
Question 11
class JJF5 {
public static void main(String args[]) {
System.out.print(Integer.toHexString(Integer.MIN_VALUE)+",");
System.out.print(Integer.toHexString(Integer.MAX_VALUE));
}}
What is the result of attempting to compile and run the program?
a. Prints: 0000,ffff
b. Prints: 00000000,ffffffff
c. Prints: 7fff,8000
d. Prints: 8000,7fff
e. Prints: 7fffffff,80000000
f. Prints: 80000000,7fffffff
g. Compile-time error
h. Run-time error
i. None of the above
Question 12
Which of the following represent the full range of type char?
a. '\u0000' to '\u7fff'
b. '\u0000' to '\uffff'
c. 0 to 32767
d. 0 to 65535
e. -32768 to 32767
f. -65536 to 65535
Question 13
Which of the following represent the full range of type char?
a. -0x8000 to 0x7fff
b. 0x0000 to 0xffff
c. -0100000 to 077777
d. 0 to 0177777
e. 0 to 32767
f. 0 to 65535
g. -32768 to 32767
Question 14
class GFM14 {
static byte a; static short b; static char c;
static int d; static long e; static String s;
public static void main(String[] args) {
System.out.println(a+","+b+","+(int)c+","+d+","+e+","+s);
}}
What is the result of attempting to compile and run the program?
a. Prints: 0,0,0,0,0,null
b. Prints: 0,0,0,0,0,
c. Prints: 0,0, ,0,0,
d. Compile-time error
e. Run-time error
f. None of the above
Question 15
class GFM15 {
static int a; static float b; static double c;
static boolean d; static String s;
public static void main(String[] args) {
System.out.println(a+","+b+","+c+","+d+","+s);
}}
What is the result of attempting to compile and run the program?
a. Prints: 0,0,0,false,null
b. Prints: 0,0,0,false,
c. Prints: 0,0.0,0.0,false,null
d. Prints: 0,0.0,0.0,false,
e. Prints: 0,0.0,0.0,true,null
f. Prints: 0,0.0,0.0,true,
g. Prints: 0,0,0,true,null
h. Prints: 0,0,0,true,
i. Compile-time error
j. Run-time error
k. None of the above
Question 16
class MWC105 {
static boolean b1;
public static void main(String[] args) {
boolean[] array = new boolean[1];
boolean b2;
System.out.print(b1+",");
System.out.print(array[0]+",");
System.out.print(b2);
}}
What is the result of attempting to compile and run the program?
a. Prints: true,true,true
b. Prints: false,false,false
c. Prints: null,null,null
d. Prints: false,true,false
e. Compile-time error
f. Run-time error
g. None of the above
Question 17
class GFM16 {
static int m1 (int i1, int i2) {
int i3;
if (i1 > 0) {i3 = i1 + i2;}
return i3;
}
public static void main(String[] args) {
System.out.println(m1(1,2));
}}
What is the result of attempting to compile and run the program?
a. Prints: 0
b. Prints: 1
c. Compile-time error
d. Run-time error
e. None of the above
Question 18
Which of these lists contains at least one word that is not a Java keyword?
a. abstract, default, if, private, this
b. do, implements, protected, boolean, throw
c. case, extends, int, short, try
d. import, break, double, exception, throws
e. byte, else, instanceof, return, transient
f. None of the above
Question 19
Which of these lists contains at least one word that is not a Java keyword?
a. interface, static, void, catch, final
b. char, strictfp, finally, long, volatile
c. native, super, class, float, while
d. const, for, new, switch, import
e. continue, finalize, goto, package, synchronized
f. None of the above
Answers of above questions are in comments link.
Comments
(Answer)An attempt to run GRC7 from the command line fails. An attempt to run GRC8 from the command line fails. An attempt to run GRC9 from the command line fails.
(Remark) Section 12.1.4 of the JLS requires the main method to be declared static. In this example, each of the three main methods are not declared static. The result is an error at run-time.
2) a
(Answer)1
(Remark)The escape sequences are as follows: '\b' (backspace), '\f' (formfeed), '\n' (newline), '\r' (carriage return), '\t' (horizontal tab), '\\' (backslash), '\"' (double quote), '\'' (single quote). Yes, you must memorize the escape sequences! Just remember "big farms need red tractors".
3) c
(Answer) 3
(Remark) The escape sequences are as follows: '\b' (backspace), '\f' (formfeed), '\n' (newline), '\r' (carriage return), '\t' (horizontal tab), '\\' (backslash), '\"' (double quote), '\'' (single quote). Yes, you must memorize the escape sequences! Just remember "big farms need red tractors".
4) l
(Answer)None of the above
(Remark)All of these are keywords of the Pascal programming language, but none are Java keywords.
5) e
(Answer) 5
The escape sequences are as follows: '\b' (backspace), '\f' (formfeed), '\n' (newline), '\r' (carriage return), '\t' (horizontal tab), '\\' (backslash), '\"' (double quote), '\'' (single quote). Yes, you must memorize the escape sequences! Just remember "big farms need red tractors".
6) b d g h
(Answer) strictfp super goto native
7) b
(Answer) Prints: null
(Remark)The System.out.print method prints the word null if the argument is a String reference that is null.
8) e
(Answer) Prints: 2,5,8
(Remark)Arrays a1, a2 and a3 all contain 3 integers. The first element of the array has an index of 0 so an index of one refers to the second element of each array.
9) c
(Answer)Prints: 7f,ffff,7fff
(Remark)A byte is an 8 bit signed value. A char is a 16 bit unsigned value. A short is a 16 bit signed value. The left most bit of a signed value is the sign bit. The sign bit is zero for positive numbers and one for negative numbers. The maximum byte value in hexadecimal format is 7f and in decimal format is 127. The minimum byte value in hexadecimal format is 80 and in decimal format is -128. The byte value of decimal -1 is ff in hexadecimal.
10) a
(Answer) 1
(Remark)A compile-time error occurs at the line marked 1, because the array reference declaration can not be used to declare the number of components contained in the array. Instead, the dimension expression should be contained in an array creation expression such as new int[5].
11) f
(Answer)Prints: 80000000,7ffffff (Remark)An int is a 32 bit signed value. The left most bit is the sign bit. The sign bit is zero for positive numbers and one for negative numbers.
12) b d
(Answer)'\u0000' to '\uffff' 0 to 65535
(Remark)A char is a 16 bit unsigned value; so none of the char values are negative and the minimum value is zero. The maximum value is 216 - 1.
13) b d f
(Answer)0x0000 to 0xffff 0 to 0177777 0 to 65535
(Remark)A char is a 16 bit unsigned value; so none of the char values are negative and the minimum value is zero. The maximum value is 216 - 1
14) a
(Answer)Prints: 0,0,0,0,0,null (Remark)The default value of type char is the null character. When it is cast to an int the value is interpreted as zero.
15) c
(Answer)Prints: 0,0.0,0.0,false,null
(Remark)Generally speaking, numeric type variables are initialized to zero. Primitive boolean variables are initialized to false. Reference type variables are initialized to null.
16) e
(Answer)Compile-time error (Remark)Variable b1 is initialized to false, because it is a class member. The array component array[0] is initialized to the default value, false, of the array type, boolean[], even though the array is declared locally. Local variable b2 is not initialized, because it is local. A compile-time error is generated by the statement that attempts to print the value of b2.
17) c
(Answer)Compile-time error
(Remark)Local variables are not initialized automatically, and must be initialized explicitly before attempting to access the value. The local variable i3 will not be initialized if i1 is less than or equal to zero; so the result is a compile-time error.
18) d
(Answer)import, break, double, exception, throws
(Remark)The word exception is not a Java keyword. The words import, break, double and throws are Java keywords.
19) e
(Answer)continue, finalize, goto, package, synchronized
(Remark)The word finalize is the name of a method of the Object class: It is not a keyword. The words continue, goto, package and synchronized are all Java keywords.