1. String in Java is a?
a) class
b) object
c) variable
d) character array
2. Which of these method of String class is used to obtain character at specified index?
a) char()
b) Charat()
c) charat()
d) charAt()
3. Which of these keywords is used to refer to member of base class from a subclass?
a) upper
b) super
c) this
d) none of the mentioned
Explanation: Whenever a subclass needs to refer to its immediate superclass, it can do so by use of the keyword super.
4. Which of these method of String class can be used to test to strings for equality?
a) isequal()
b) isequals()
c) equal()
d) equals()
5. Which of the following statements are incorrect?
a) String is a class
b) Strings in java are mutable
c) Every string is an object of class String
d) Java defines a peer class of String, called StringBuffer, which allows string to be altered
Explanation: Strings in Java are immutable that is they can not be modified.
6. What will be the output of the following Java program?
class string_demo
{
public static void main(String args[])
{
String obj = "I" + "like" + "Java";
System.out.println(obj);
}
}
a) I
b) like
c) Java
d) IlikeJava
Explanation: Java defines an operator +, it is used to concatenate strings.
7. What will be the output of the following Java program?
class string_class
{
public static void main(String args[])
{
String obj = "I LIKE JAVA";
System.out.println(obj.charAt(3));
}
}
a) I
b) L
c) K
d) E
Explanation: charAt() is a method of class String which gives the character specified by the index. obj.charAt(3) gives 4th character i:e I.
8. What will be the output of the following Java program?
class string_class
{
public static void main(String args[])
{
String obj = "I LIKE JAVA";
System.out.println(obj.length());
}
}
a) 9
b) 10
c) 11
d) 12
9. What will be the output of the following Java program?
class string_class
{
public static void main(String args[])
{
String obj = "hello";
String obj1 = "world";
String obj2 = obj;
obj2 = " world";
System.out.println(obj + " " + obj2);
}
}
a) hello hello
b) world world
c) hello world
d) world hello
10. What will be the output of the following Java program?
class string_class
{
public static void main(String args[])
{
String obj = "hello";
String obj1 = "world";
String obj2 = "hello";
System.out.println(obj.equals(obj1) + " " + obj.equals(obj2));
}
}
a) false false
b) true true
c) true false
d) false true
Explanation: equals() is method of class String, it is used to check equality of two String objects, if they are equal, true is retuned else false.