250+ TOP MCQs on Java.lang – Class and Answers [2024]

Java MCQs Class of java.lang library of Java Programming Language.

1. Which of these classes encapsulate runtime state of an object?
a) Class
b) System
c) Runtime
d) Cache

Answer: a
Clarification: None.

2. Which of these methods returns the class of an object?
a) getClass()
b) Class()
c) WhoseClass()
d) WhoseObject()

Answer: a
Clarification: None.

3. Which of these methods return a class object given its name?
a) getClass()
b) findClass()
c) getSystemClass()
d) findSystemClass()

Answer: d
Clarification: findSystemClass() returns a class object given its name.

4. Which of these class defines how the classes are loaded?
a) Class
b) System
c) Runtime
d) ClassLoader

Answer: d
Clarification: None.

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

```
    class X 
```
```
    {
```
```
        int a;
```
```
        double b;
```
```
    }
```
```
    class Y extends X 
```
```
    {
```
```
	int c;
```
```
    }
```
```
    class Output 
```
```
    {
```

        public static void main(String args[])

```
        {
```
```
            X a = new X();
```
```
            Y b = new Y();
```
```
            Class obj;
```
```
            obj = a.getClass();
```

            System.out.print(obj.getName());

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

a) X
b) Y
c) a
d) b

Answer: a
Clarification: getClass() is used to obtain the class of an object, here ‘a’ is an object of class ‘X’. hence a.getClass() returns ‘X’ which is stored in class Class object obj.
Output:

$ javac Output.java
$ java Output
X

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

```
    class X
```
```
    {
```
```
        int a;
```
```
        double b;
```
```
    }
```
```
    class Y extends X 
```
```
    {
```
```
	int c;
```
```
    }
```
```
    class Output 
```
```
    {
```

        public static void main(String args[])

```
        {
```
```
            X a = new X();
```
```
            Y b = new Y();
```
```
            Class obj;
```
```
            obj = b.getClass();
```

            System.out.print(obj.getSuperclass());

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

a) X
b) Y
c) class X
d) class Y

Answer: c
Clarification: getSuperClass() returns the super class of an object. b is an object of class Y which extends class X, Hence Super class of b is X. therefore class X is printed.
Output:

$ javac Output.java
$ java Output
class X

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

```
    class X 
```
```
    {
```
```
        int a;
```
```
        double b;
```
```
    }
```
```
    class Y extends X 
```
```
    {
```
```
	int c;
```
```
    }
```
```
    class Output 
```
```
    {
```

        public static void main(String args[])

```
        {
```
```
            X a = new X();
```
```
            Y b = new Y();
```
```
            Class obj;
```
```
            obj = b.getClass();
```

            System.out.print(obj.isLocalClass());

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

a) 0
b) 1
c) true
d) false

Answer: d
Clarification: None.
Output:

$ javac Output.java
$ java Output
false

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