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
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