250+ TOP MCQs on Java.lang – Integer, Long & Character Wrappers and Answers [2024]

Java MCQs on Integer, Long & Character wrappers of Java Programming Language.

1. Which of these is a wrapper for data type int?
a) Integer
b) Long
c) Byte
d) Double

Answer: a
Clarification: None.

2. Which of the following methods is a method of wrapper Integer for obtaining hash code for the invoking object?
a) int hash()
b) int hashcode()
c) int hashCode()
d) Integer hashcode()

Answer: c
Clarification: None.

3. Which of these is a super class of wrappers Long, Character & Integer?
a) Long
b) Digits
c) Float
d) Number

Answer: d
Clarification: Number is an abstract class containing subclasses Double, Float, Byte, Short, Integer and Long.

4. Which of these is a wrapper for simple data type char?
a) Float
b) Character
c) String
d) Integer

Answer: b
Clarification: None.

5. Which of the following is method of wrapper Integer for converting the value of an object into int?
a) bytevalue()
b) int intValue();
c) Bytevalue()
d) Byte Bytevalue()

Answer: b
Clarification: None.

6. Which of these methods is used to obtain value of invoking object as a long?
a) long value()
b) long longValue()
c) Long longvalue()
d) Long Longvalue()

Answer: b
Clarification: long longValue() is used to obtain value of invoking object as a long.

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

```
    class Output 
```
```
    {
```

        public static void main(String args[])

```
        {
```

            char a[] = {'a', '5', 'A', ' '};

            System.out.print(Character.isDigit(a[0]) + " ");

            System.out.print(Character.isWhitespace(a[3]) + " ");

            System.out.print(Character.isUpperCase(a[2]));

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

a) true false true
b) false true true
c) true true false
d) false false false

Answer: b
Clarification: Character.isDigit(a[0]) checks for a[0], whether it is a digit or not, since a[0] i:e ‘a’ is a character false is returned. a[3] is a whitespace hence Character.isWhitespace(a[3]) returns a true. a[2] is an uppercase letter i:e ‘A’ hence Character.isUpperCase(a[2]) returns true.
Output:

$ javac Output.java
$ java Output
false true true

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

```
    class Output 
```
```
    {
```

        public static void main(String args[])

```
        {
```

            Integer i = new Integer(257);

```
            byte x = i.byteValue();
```
```
            System.out.print(x);
```
```
        }
```
```
    }
```

a) 0
b) 1
c) 256
d) 257

Answer: b
Clarification: i.byteValue() method returns the value of wrapper i as a byte value. i is 257, range of byte is 256 therefore i value exceeds byte range by 1 hence 1 is returned and stored in x.
Output:

$ javac Output.java
$ java Output
1

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

```
    class Output 
```
```
    {
```

        public static void main(String args[])

```
        {
```

            Integer i = new Integer(257);

```
            float x = i.floatValue();
```
```
            System.out.print(x);
```
```
        }
```
```
    }
```

a) 0
b) 1
c) 257
d) 257.0

Answer: d
Clarification: None.
Output:

$ javac Output.java
$ java Output
257.0

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

```
    class Output 
```
```
    {
```

        public static void main(String args[])

```
        {
```
```
            Long i = new Long(256);  
```

            System.out.print(i.hashCode());

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

a) 256
b) 256.0
c) 256.00
d) 257.00

Answer: a
Clarification: None.
Output:

$ javac Output.java
$ java Output
256

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