1. What will be the output of the following Java code?
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]);
}
}
a) ab
b) bc
c) ca
d) ac
Explanation: 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:
ac
2. Which of this method of class String is used to extract a substring from a String object?
a) substring()
b) Substring()
c) SubString()
d) None of the mentioned
Explanation: substring()
3. What will s2 contain after following lines of Java code?
String s1 = "one";
String s2 = s1.concat("two")
a) one
b) two
c) onetwo
d) twoone
Explanation: Two strings can be concatenated by using concat() method.
4. Which of these method of class String is used to remove leading and trailing whitespaces?
a) startsWith()
b) trim()
c) Trim()
d) doTrim()
Explanation: trim()
5. What is the value returned by function compareTo() if the invoking string is greater than the string compared?
a) zero
b) value less than zero
c) value greater than zero
d) none of the mentioned
Explanation: if (s1 == s2) then 0, if(s1 > s2) > 0, if (s1 < s2) then < 0.
6. Which of the following statement is correct?
a) replace() method replaces all occurrences of one character in invoking string with another character
b) replace() method replaces only first occurrences of a character in invoking string with another character
c) replace() method replaces all the characters in invoking string with another character
d) replace() replace() method replaces last occurrence of a character in invoking string with another character
Explanation: replace() method replaces all occurrences of one character in invoking string with another character.
7. What will be the output of the following Java program?
class output
{
public static void main(String args[])
{
String c = " Hello World ";
String s = c.trim();
System.out.println("\""+s+"\"");
}
}
a) “”Hello World””
b) “”Hello World”
c) “Hello World”
d) Hello world
Explanation: trim() method is used to remove leading and trailing whitespaces in a string.
Output:
"Hello World"
8. What will be the output of the following Java program?
class output
{
public static void main(String args[])
{
String s1 = "one";
String s2 = s1 + " two";
System.out.println(s2);
}
}
a) one
b) two
c) one two
d) compilation error
Explanation:
Output:
one two
9. What will be the output of the following Java program?
class output
{
public static void main(String args[])
{
String s1 = "Hello";
String s2 = s1.replace('l','w');
System.out.println(s2);
}
}
a) hello
b) helwo
c) hewlo
d) hewwo
Explanation: replace() method replaces all occurrences of one character in invoking string with another character. s1.replace(‘l’,’w’) replaces every occurrence of ‘l’ in hello by ‘w’, giving hewwo.
Output:
hewwo
10. What will be the output of the following Java program?
class output
{
public static void main(String args[])
{
String s1 = "Hello World";
String s2 = s1.substring(0 , 4);
System.out.println(s2);
}
}
a) Hell
b) Hello
c) Worl
d) World
Explanation: substring(0,4) returns the character from 0 th position to 3 rd position.
output:
Hell