String Handling Basics - Java Questions & Answers

This section of our 1000+ Java MCQs focuses on string handling in Java Programming Language.

1. Which of these class is superclass of String and StringBuffer class?
a) java.util
b) java.lang
c) ArrayList
d) None of the mentioned
View Answer

Answer: b
Explanation: None.

2. Which of these operators can be used to concatenate two or more String objects?
a) +
b) +=
c) &
d) ||
View Answer

Answer: a
Explanation: Operator + is used to concatenate strings, Example String s = “i ” + “like ” + “java”; String s contains “I like java”.

3. Which of these method of class String is used to obtain length of String object?
a) get()
b) Sizeof()
c) lengthof()
d) length()
View Answer

Answer: d
Explanation: Method length() of string class is used to get the length of the object which invoked method length().

4. Which of these method of class String is used to extract a single character from a String object?
a) CHARAT()
b) chatat()
c) charAt()
d) ChatAt()
View Answer

Answer: c
Explanation: None.

5. Which of these constructors is used to create an empty String object?
a) String()
b) String(void)
c) String(0)
d) None of the mentioned
View Answer

Answer: a
Explanation: None.

6. Which of these is an oncorrect statement?
a) String objects are immutable, they cannot be changed
b) String object can point to some other reference of String variable
c) StringBuffer class is used to store string in a buffer for later use
d) None of the mentioned
View Answer

Answer: c
Explanation: StringBuffer class is used to create strings that can be modified after they are created.

7. 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);
```
```
        }
```
```
   }
```

a) a
b) b
c) c
d) abc
View Answer

Answer: d
Explanation: 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

8. 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);
```
```
        }
```
```
   }
```

a) ABC
b) BCD
c) CDA
d) ABCD
View Answer

Answer: b
Explanation: 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

9. 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);

```
        }
```
```
   }
```

a) 3 0
b) 0 3
c) 3 4
d) 4 3
View Answer

Answer: d
Explanation: None.
output:
$ javac String_demo.java
$ java String_demo
4 3

10. 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());

```
        }
```
```
   }
```

a) True
b) False
c) String associated with obj1
d) Compilation Error
View Answer

Answer: c
Explanation: 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
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