Java Programming - 1.4 Operators

1. What will be the output of the following JAVA code?

class LWD{

public static void main(String arg[]){

int a=b=c=d=9;

System.out.println(a+" "+b+" "+c+" "+d);

}

}

Output & Explanation:

Compile time error

In the above JAVA code, variable a is declared and initialized with the integer value 9, rest of the variable b, c and d are not declared. Hence it shows can't find the symbol error during compilation time.

In-order to avoid this error, we can declare and initialize the variables as mentioned below:

int a,b,c,d; 

a=b=c=d=9; // valid declaration

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2. What will be the output of the following JAVA code?

class  LWD{

        public static void main(String args[])

        {

int l,d;

l=9;

d=7;

float l1,d1;

l1=9.0f;

d1=7.0f;

int result[]={l+d,l-d,l*d,l/d,l%d};

float result1[]={l1+d1,l1-d1,l1*d1,l1/d1,l1%d1};

for(int i=0;i<result.length;i++){

System.out.println("Int result & float result1:"+result[i]+" & "+result1[i]);

}

       } 

}

Output & Explanation:

Int result & float result1: 16 & 16.0

Int result & float result1: 2 & 2.0

Int result & float result1: 63 & 63.0

Int result & float result1: 1 & 1.2857143

Int result & float result1: 2 & 2.0

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3. What will be the output of the following JAVA code?

class LWD{

      public static void main(String args[]){   

             int a,b;

a=5;b=6; 

int result[]={a & b,a|b ,a^b};

for(int i=0;i<result.length;i++)

System.out.println("result="+result[i]);

      }

 }

Output & Explanation:

result=4

result=7

result=3

A	B	Bitwise &	Bitwise |	Bitwise ^
0	0	0	0	0
0	1	0	1	1
1	0	0	1	1
1	1	1	1	0

Given that, 

5 - 0101	0101   0110	0101   0110	0101   0110
6 - 0110
Result	&0100à4	| 0111 à7	^ 0011 à3

4. What will be the output of the following JAVA code?

class LWD{

        public static void main(String args[]){   

           byte a=1;

   a=a+1;

   System.out.println(a);

        }

    }

Output & Explanation:

Compile time error due to incompitable type, lossy conversion from int to byte.

byte+byte=int, integer can't be stored in byte variable.

5. What will be the output of the following JAVA code?

class A{}

class B{}

class LWD extends A{

public static void main(String args[]){

A a=new LWD();

B b=new B();

LWD l=new LWD();

System.out.println(a instanceof LWD); 

System.out.println(b instanceof B);

System.out.println(l instanceof LWD);

}

}

Output & Explanation:

false

true

true

instanceof operator used to check the object is comes from the respective class instance or not.

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6. What will be the output of the following JAVA code?

class Samsung{

static int i=5;

void disp(){

System.out.println(i--);

System.out.println(i--);

}

}

class Mobile{

public static void main(String arg[]){

Samsung m1=new Samsung();

m1.disp();

Samsung m2=new Samsung();

m2.disp();

}

}

Output & Explanation:

5

4

3

2

Static variable is used to initialize the variable only once in the program.  disp() function called with m1 and m2 instance, m1.disp() prints twice the value of i--(i--=5 and i--=4) and being statice variable m2.disp() prints again twice the value of i-- (i-- =3 and i-- =2). 

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7. What will be the output of the following JAVA code?

class LWD{

public static void main(String L[]){

int x=20,y=15;

if(++x>10 || ++y>15)

x++;

else

y++;

System.out.println(x+" "+y);

}

}

Output & Explanation:

22 15

Bitwise &, |	Logical &&, ||
Both arguments should be evaluated always. x & y à Even if x is false, y will also be evaluated. x | y à Even if x is true, y will also be evaluated.	Second argument evaluation is optional. x&&y à If x is true then only y will be evaluated. x || y à If x is false the only y will be evaluated.
Relatively performance is low	Relatively performance is high
Applicable for integer and Boolean types.	Applicable only for Boolean types but not for integer types.

Given that, x=20 and y=15

Operator	x	Y
&&	22	16
||	22	15
&	22	16
|	22	16