variables questions on java with explanation

Questions on variables in java with answers

(1)

public class Test {

    public static void main(String[] args) {

         int a=5;

         {

             Integer b=10;

         }

         int c=a+b;

         System.out.println(c);

    }

}

What will output when you compile and run the above code?

(a)15

(b)5

(c)Compiler error

(d) Run time error

Answer: (c)

Explanation:

Scope of the any variable in a function is the braces in which it has been declared. Variable a has been declared within main function braces. So its scope is whole the main function while variable b has been declared in another braces so its scope and visibility is only that block or braces. After that block variable a is visible while variable b has dead.

So, It is error to write int c=a+b;

(2)

public class Loop {

    public static void main(String[] args) {

         for(int i=-0;i<3;i++){

             System.out.print(i);

         }

         System.out.print(i);

    }

}

What will output when you compile and run the above code?

(a) 0 1 2 3

(b) 0 1 2 2

(c) 0 0 1 2

(d) Compiler error

Answer: (d)

Explanation:

Scope of the any variable is in a function or loop or the only braces in which it has been declared. Variable i has been declared within for loop. So it is not visible to outside the for loop

Identifier

(3)

public class Identifier {

    public static void main(String[] args) {

         int a$=5;

         Integer b$=10;

         int _c=a$+b$;

         System.out.print(_c);

            

    }

}

What will output when you compile and run the above code?

(a) 15

(b) 50

(c) Compile time error

(d) Run time error

Answer: (a)

Explanation:

    _c=5+10=15.

In java variable name can be start with underscore (_) and it can contain special character dollar singe ($)

(4)

public class Identifier {

    public static void main(String[] args) {

         int $=5;

         final byte $$=-10;

         int _$=$+$$;

         System.out.print(_$);

            

    }

}

What will output when you compile and run the above code?

(a)-5

(b) 5

(c) 105

(d) Error

Answer: (a)

Explanation:

    -$=5+ (-10) =-5

In java programming language variable name includes alphabet, digits few special characters like underscore (_), dollar singe ($).

(5)

public class Identifier {

    public static void main(String[] args) {

         int _=5;

         short __ =2;

         int ___=__-~_;

         System.out.print(___);

            

    }

}

What will output when you compile and run the above code?

(a) 2

(b) 4

(c) 8

(d)Error

Answer: (c)

Explanation:

    In java programming language variable name includes alphabet, digits few special characters like underscore (_), dollar singe ($).

Here _ (one underscore), __ (two underscore) or ___ (three underscore) are valid name of any variable.

So, ___=2+~5=2-(-6) =2+6=8

Note: ~ is 1’s complementing operator.


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