Input & Output Basics - Java Questions & Answers

This section of our 1000+ Java MCQs focuses on creating threads in Java Programming Language.

1. What does AWT stands for?
a) All Window Tools
b) All Writing Tools
c) Abstract Window Toolkit
d) Abstract Writing Toolkit
View Answer

Answer: c
Explanation: AWT stands for Abstract Window Toolkit, it is used by applets to interact with the user.

2. Which of these is used to perform all input & output operations in Java?
a) streams
b) Variables
c) classes
d) Methods
View Answer

Answer: a
Explanation: Like in any other language, streams are used for input and output operations.

3. Which of these is a type of stream in Java?
a) Integer stream
b) Short stream
c) Byte stream
d) Long stream
View Answer

Answer: c
Explanation: Java defines only two types of streams – Byte stream and character stream.

4. Which of these classes are used by Byte streams for input and output operation?
a) InputStream
b) InputOutputStream
c) Reader
d) All of the mentioned
View Answer

Answer: a
Explanation: Byte stream uses InputStream and OutputStream classes for input and output operation.

5. Which of these classes are used by character streams for input and output operations?
a) InputStream
b) Writer
c) ReadStream
d) InputOutputStream
View Answer

Answer: b
Explanation: Character streams uses Writer and Reader classes for input & output operations.

6. Which of these class is used to read from byte array?
a) InputStream.
b) BufferedInputStream.
c) ArrayInputStream.
d) ByteArrayInputStream.
View Answer

Answer: d
Explanation: None.

7. What is the output of this program if input given is ‘abcqfghqbcd’?

```
    class Input_Output
```
```
    {
```

        public static void main(String args[]) throws IOException

```
        {	 
```
```
            char c;
```

            BufferedReader obj = new BufferedReader(new InputStreamReader(System.in));

```
            do
```
```
            {
```
```
                c = (char) obj.read();
```
```
	        System.out.print(c);
```
```
            } while(c != 'q');
```
```
        }
```
```
    }
```

a) abcqfgh
b) abc
c) abcq
d) abcqfghq
View Answer

Answer: c
Explanation: None.
Output:

$ javac Input_Output.java
$ java Input_Output
abcq

8. What is the output of this program if input given is “abc’def/’egh”?

```
    class Input_Output
```
```
    {
```

        public static void main(String args[]) throws IOException

```
        {	 
```
```
            char c;
```

            BufferedReader obj = new BufferedReader(new InputStreamReader(System.in));

```
            do 
```
```
            {
```
```
                c = (char) obj.read();
```
```
	        System.out.print(c);
```
```
            } while(c!='\'');
```
```
        }
```
```
    }
```

a) abc’
b) abcdef/’
c) abc’def/’egh
d) abcqfghq
View Answer

Answer: a
Explanation: \’ is used for single quotes that is for representing ‘ .
Output:

$ javac Input_Output.java
$ java Input_Output
abc'

9. What is the output of this program?

```
    class output
```
```
    {
```

        public static void main(String args[])

```
        { 
```

             StringBuffer c = new StringBuffer("Hello");

             System.out.println(c.length());

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

a) 4
b) 5
c) 6
d) 7
View Answer

Answer: b
Explanation: length() method is used to obtain length of StringBuffer object, length of “Hello” is 5.
Output:

$ javac output.java
$ java output
5

10. What is the output of this program?

```
    class output
```
```
    {
```

        public static void main(String args[])

```
        { 
```

           StringBuffer s1 = new StringBuffer("Hello");

           StringBuffer s2 = s1.reverse();

```
           System.out.println(s2);
```
```
        }
```
```
    }
```

a) Hello
b) olleH
c) HelloolleH
d) olleHHello
View Answer

Answer: b
Explanation: reverse() method reverses all characters. It returns the reversed object on which it was called.
Output:

$ javac output.java
$ java output
olleH

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