250+ TOP MCQs on Recursion and Answers

Java MCQs on recursion of Java Programming Language.

1. What is Recursion in Java?
a) Recursion is a class
b) Recursion is a process of defining a method that calls other methods repeatedly
c) Recursion is a process of defining a method that calls itself repeatedly
d) Recursion is a process of defining a method that calls other methods which in turn call again this method

Answer: b
Clarification: Recursion is the process of defining something in terms of itself. It allows us to define a method that calls itself.

2. Which of these data types is used by operating system to manage the Recursion in Java?
a) Array
b) Stack
c) Queue
d) Tree

Answer: b
Clarification: Recursions are always managed by using stack.

3. Which of these will happen if recursive method does not have a base case?
a) An infinite loop occurs
b) System stops the program after some time
c) After 1000000 calls it will be automatically stopped
d) None of the mentioned

Answer: a
Clarification: If a recursive method does not have a base case then an infinite loop occurs which results in Stack Overflow.

4. Which of these is not a correct statement?
a) A recursive method must have a base case
b) Recursion always uses stack
c) Recursive methods are faster that programmers written loop to call the function repeatedly using a stack
d) Recursion is managed by Java Runtime environment

Answer: d
Clarification: Recursion is always managed by operating system.

5. Which of these packages contains the exception Stack Overflow in Java?
a) java.lang
b) java.util
c) java.io
d) java.system

Answer: a
Clarification: None.

6. What will be the output of the following Java program?

```
    class recursion 
```
```
    {
```
```
        int func (int n) 
```
```
        {
```
```
            int result;
```
```
            result = func (n - 1);
```
```
            return result;
```
```
        }
```
```
    } 
```
```
    class Output 
```
```
    {
```

        public static void main(String args[])

```
        {
```

            recursion obj = new recursion() ;

            System.out.print(obj.func(12));

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

a) 0
b) 1
c) Compilation Error
d) Runtime Error

Answer: d
Clarification: Since the base case of the recursive function func() is not defined hence infinite loop occurs and results in Stack Overflow.
Output:

$ javac Output.javac
$ java Output
Exception in thread "main" java.lang.StackOverflowError

7. What will be the output of the following Java program?

```
    class recursion 
```
```
    {
```
```
        int func (int n) 
```
```
        {
```
```
            int result;
```
```
            if (n == 1)
```
```
                return 1;
```
```
            result = func (n - 1);
```
```
            return result;
```
```
        }
```
```
    } 
```
```
    class Output 
```
```
    {
```

        public static void main(String args[])

```
        {
```

            recursion obj = new recursion() ;

            System.out.print(obj.func(5));

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

a) 0
b) 1
c) 120
d) None of the mentioned

Answer: b
Clarification: None.
Output:

$ javac Output.javac
$ java Output
1

8. What will be the output of the following Java program?

```
    class recursion 
```
```
    {
```
```
        int fact(int n) 
```
```
        {
```
```
            int result;
```
```
            if (n == 1)
```
```
                return 1;
```
```
            result = fact(n - 1) * n;
```
```
            return result;
```
```
        }
```
```
    } 
```
```
    class Output 
```
```
    {
```

        public static void main(String args[])

```
        {
```

            recursion obj = new recursion() ;

            System.out.print(obj.fact(5));

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

a) 24
b) 30
c) 120
d) 720

Answer: c
Clarification: fact() method recursively calculates factorial of a number, when value of n reaches 1, base case is excuted and 1 is returned.
Output:

$ javac Output.javac
$ java Output
120

9. What will be the output of the following Java program?

```
    class recursion 
```
```
    {
```
```
        int fact(int n) 
```
```
        {
```
```
            int result;
```
```
            if (n == 1)
```
```
                return 1;
```
```
            result = fact(n - 1) * n;
```
```
            return result;
```
```
        }
```
```
    } 
```
```
    class Output 
```
```
    {
```

        public static void main(String args[])

```
        {
```

            recursion obj = new recursion() ;

            System.out.print(obj.fact(1));

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

a) 1
b) 30
c) 120
d) Runtime Error

Answer: a
Clarification: fact() method recursively calculates factorial of a number, when value of n reaches 1, base case is excuted and 1 is returned.
Output:

$ javac Output.javac
$ java Output
1

10. What will be the output of the following Java program?

```
    class recursion 
```
```
    {
```
```
        int fact(int n) 
```
```
        {
```
```
            int result;
```
```
            if (n == 1)
```
```
                return 1;
```
```
            result = fact(n - 1) * n;
```
```
            return result;
```
```
        }
```
```
    } 
```
```
    class Output 
```
```
    {
```

        public static void main(String args[])

```
        {
```

            recursion obj = new recursion() ;

            System.out.print(obj.fact(6));

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

a) 1
b) 30
c) 120
d) 720

Answer: d
Clarification: None.
Output:

$ javac Output.javac
$ java Output
720

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250+ TOP MCQs on Recursion and Answers

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