Questions and answers for exam Preparation

MCQs

Total Questions : 29 | Page 1 of 3 pages

What is the output of this program?

class A {
int i;
int j;
A() {
i = 1;
j = 2;
}
}
class Output {
public static void main(String args[])
{
A obj1 = new A();
System.out.print(obj1.toString());
}
}

true
false
String associated with obj1
Compilation Error

Discuss Question

Answer: Option C. -> String associated with obj1

toString() is method of class Object, since it is superclass of every class, every object has this

method. toString() returns the string associated with the calling object.

output:
$ javac Output.java
$ java Output
A@1cd2e5f

Question 2.

What is the output of this program?

class output {
public static void main(String args[])
{
String chars[] = {"a", "b", "c", "a", "c"};
for (int i = 0; i < chars.length; ++i)
for (int j = i + 1; j < chars.length; ++j)
if(chars[i].compareTo(chars[j]) == 0)
System.out.print(chars[j]);
}
}

Discuss Question

Answer: Option D. -> ac

compareTo() function returns zero when both the strings are equal, it returns a value less than

zero if the invoking string is less than the other string being compared and value greater than

zero when invoking string is greater than the string compared to.
output:
$ javac output.java
$ java output
ac

Question 3.

What is the output of this program?

class String_demo {
public static void main(String args[])
{
char chars[] = {'a', 'b', 'c'};
String s = new String(chars);
String s1 = "abcd";
int len1 = s1.length();
int len2 = s.length();
System.out.println(len1 + " " + len2);
}
}

Discuss Question

Answer: Option D. -> 4 3

None.
output:
$ javac String_demo.java
$ java String_demo
4 3

Question 4.

What is the output of this program?

class output {
public static void main(String args[])
{
char ch;
ch = "hello".charAt(1);
System.out.println(ch);
}
}

Discuss Question

Answer: Option B. -> e

"hello" is a String literal, method charAt() returns the character specified at the index position.

Character at index position 1 is e of hello, hence ch contains e.
output:
$ javac output.java
$ java output
e

Question 5.

What is the output of this program?

class output {
public static void main(String args[])
{ String s = "Hello World";
int i = s.indexOf('o');
int j = s.lastIndexOf('l');
System.out.print(i + " " + j);
}
}

Discuss Question

Answer: Option C. -> 4 9

indexOf() method returns the index of first occurrence of the character where as lastIndexOf()

returns the index of last occurrence of the character.
output:
$ javac output.java
$ java output
4 9

Question 6.

What is the output of this program?

class String_demo {
public static void main(String args[])
{
int ascii[] = { 65, 66, 67, 68};
String s = new String(ascii, 1, 3);
System.out.println(s);
}
}

ABC
BCD
CDA
ABCD

Discuss Question

Answer: Option B. -> BCD

ascii is an array of integers which contains ascii codes of Characters A, B, C, D. String(ascii, 1, 3)

is an constructor which initializes s with Characters corresponding to ascii codes stored in array ascii,

starting position being given by 1 & ending position by 3, Thus s stores BCD.
output:
$ javac String_demo.java
$ java String_demo
BCD

Question 7.

What is the output of this program?

class output {
public static void main(String args[])
{
String s1 = "Hello World";
String s2 = s1.substring(0 , 4);
System.out.println(s2);
}
}

Hell
Hello
Worl
World

Discuss Question

Answer: Option A. -> Hell

substring(0,4) returns the character from 0 th position to 3 rd position.
output:
$ javac output.java
$ java output
Hell

Question 8.

What is the output of this program?

class String_demo {
public static void main(String args[])
{
char chars[] = {'a', 'b', 'c'};
String s = new String(chars);
System.out.println(s);
}
}

Discuss Question

Answer: Option D. -> abc

String(chars) is a constructor of class string, it initializes string s with the values stored in character

array chars, therefore s contains "abc".
output:
$ javac String_demo.java
$ java String_demo
abc

Question 9.

What is the output of this program?

class output {
public static void main(String args[])
{
String s1 = "Hello";
String s2 = new String(s1);
String s3 = "HELLO";
System.out.println(s1.equals(s2) + " " + s2.equals(s3));
}
}

true true
false false
true false
false true

Discuss Question

Answer: Option C. -> true false

None.
Output:
$ javac output.java
$ java output
true false

Question 10.

What is the output of this program?

class output {
public static void main(String args[])
{
String s1 = "Hello i love java";
String s2 = new String(s1);
System.out.println((s1 == s2) + " " + s1.equals(s2));
}
}