add two integers

[sridhar19]

i need add two integers in java codeing

[r035198x]

i need add two integers in java codeing

Are you having any specific problems with it? Does the user have to supply the integers or are hardcoding the integers to be added in there.

[JosAH]

i need add two integers in java codeing

For primitive 'int's your question is hilarious; for Integers have a look at autoboxing,
i.e. starting at Java 1.5 you can simply do this:

Integer a= new Integer(41);
Integer b= new Integer(13);
Integer c;
 
c= a+b;
 

For Java < 1.5 you have to do this:

Integer a= new Integer(41);
Integer b= new Integer(13);
Integer c;
 
c= new Integer(a.intValue()+b.intValue());
 

kind regards,

Jos

[blazedaces]

For primitive 'int's your question is hilarious; for Integers have a look at autoboxing,
i.e. starting at Java 1.5 you can simply do this:

Integer a= new Integer(41);
Integer b= new Integer(13);
Integer c;
 
c= a+b;
 

For Java < 1.5 you have to do this:

Integer a= new Integer(41);
Integer b= new Integer(13);
Integer c;
 
c= new Integer(a.intValue()+b.intValue());
 

kind regards,

Jos

I didn't know this, just tested it out, but you can even do the following:

public class testIntegerAdding {
 
    public static void main(String args[]) {
        Integer a = new Integer(13);
        Double b = new Double(12.5);
 
        Double c = a + b;
        System.out.println(c);
    }
}
 

-blazed

[JosAH]

I didn't know this, just tested it out, but you can even do the following:

public class testIntegerAdding {
 
    public static void main(String args[]) {
        Integer a = new Integer(13);
        Double b = new Double(12.5);
 
        Double c = a + b;
        System.out.println(c);
    }
}
 

-blazed

Autoboxing is a disease; have a look at this:

Integer a = 42, b = 42;
Integer c = 129, d = 129;
System.out.println( a == 42 ); // true
System.out.println( a == b ); // true
System.out.println( c == 129 ); // true
System.out.println( c == d ); // false
 

kind regards,

Jos

[r035198x]

Autoboxing is a disease; have a look at this:

Integer a = 42, b = 42;
Integer c = 129, d = 129;
System.out.println( a == 42); // true
System.out.println( a == b ); // true
System.out.println( c == 129 ); // true
System.out.println( c == d ); // false
 

kind regards,

Jos

Hey, I can't test this now but does a == 10 really give true?

[JosAH]

Hey, I can't test this now but does a == 10 really give true?

Ten? I don't see no ten in my post! :-P seriously though, that was a typo; I
remembered that silly example and typed it in from the top of my head.
10 should be 42. The results still are surprising.

kind regards,

Jos

[r035198x]

Ten? I don't see no ten in my post! :-P seriously though, that was a typo; I
remembered that silly example and typed it in from the top of my head.
10 should be 42. The results still are surprising.

kind regards,

Jos

Yep, when both operands are reference types no autoboxing occurs.

[JosAH]

Yep, when both operands are reference types no autoboxing occurs.

That's not the reason: auto(un)boxing only occurs when one of the types isn't
a reference type, e.g. Integer vs int. Here's a better example:

public boolean check(Integer x, Integer y) {
 
   if (!(x < y || y < x))
      return x == y; // most certainly x == y
   else
      return false // most certainly x != y
}
...
Integer x= 42, y= 42;
System.out.println(check(x, y)); // true;
 
Integer x= 142, y= 142;
System.out.println(check(x, y)); // false;
 

kind regards,

Jos ;-)

[r035198x]

That's not the reason: auto(un)boxing only occurs when one of the types isn't
a reference type, e.g. Integer vs int. Here's a better example:

public boolean check(Integer x, Integer y) {
 
   if (!(x < y || y < x))
      return x == y; // most certainly x == y
   else
      return false // most certainly x != y
}
...
Integer x= 42, y= 42;
System.out.println(check(x, y)); // true;
 
Integer x= 142, y= 142;
System.out.println(check(x, y)); // false;
 

kind regards,

Jos ;-)

I still don't see how my reason is different from the one you gave.

[JosAH]

I still don't see how my reason is different from the one you gave.

It's not about autoboxing itself: the puzzle is about why is 42 == 42 true while
142 == 142 is false. for both cases (x < y || y < x) is false (so mathematically
speaking x == y should be true.

kind regards,

Jos

[r035198x]

Oh yeah, I've tested it now with

class Test {
   public static void main(String[] args) {
    Integer x= 127, y= 127;
    System.out.println(check(x, y));
    Integer a= 128, b= 128;
    System.out.println(check(a, b)); 
   }
   public static boolean check(Integer x, Integer y) {
    if (!(x < y || y < x))
       return x == y; 
    else
       return false ;
    }
}

I should have known you were up to your tricks again.

[JosAH]

Oh yeah, I've tested it now with

class Test {
   public static void main(String[] args) {
    Integer x= 127, y= 127;
    System.out.println(check(x, y));
    Integer a= 128, b= 128;
    System.out.println(check(a, b)); 
   }
   public static boolean check(Integer x, Integer y) {
    if (!(x < y || y < x))
       return x == y; 
    else
       return false ;
    }
}

I should have known you were up to your tricks again.

Cute eh? That's why I wrote that autoboxing is a disease. ;-)

kind regards,

Jos

[r035198x]

Cute eh? That's why I wrote that autoboxing is a disease. ;-)

kind regards,

Jos

It has always looked suspicious.
I'm always suspicious of everything that begins with auto. Except for automobile of course.

[blazedaces]

It's not about autoboxing itself: the puzzle is about why is 42 == 42 true while
142 == 142 is false. for both cases (x < y || y < x) is false (so mathematically
speaking x == y should be true.

kind regards,

Jos

I didn't try it... but why does 142 == 142 output false? Btw, is autoboxing the process which checks "=="? I'm confused...

-blazed

[JosAH]

I didn't try it... but why does 142 == 142 output false? Btw, is autoboxing the process which checks "=="? I'm confused...

-blazed

Just give the example above a try and see for yourself.

kind regards,

Jos (old bag of old tricks ;-)

[blazedaces]

Just give the example above a try and see for yourself.

kind regards,

Jos (old bag of old tricks ;-)

Ok, so I tried the following:

public class testSomething {
 
    public static void main(String args[]) {
        Integer a = 42, b = 42;
        Integer c = 129, d = 129;
        System.out.println( a == 42 ); // true
        System.out.println( a == b ); // true
        System.out.println( c == 129 ); // true
        System.out.println( d == 129 ); // true
        System.out.println( c == d ); // false
        System.out.println( c.intValue() == d.intValue() ); // true
    }
}
 

I can only assume from the information thus far that after one byte's value (signed) or at a value greater then or equal to 128 Integer no longer stores its numbers the same way... I do not know why or how.

I'm trying to think of some other tests to try and understand this...

Perhaps "==" isn't as simple as I thought it was?

I don't know...

-blazed

[mahammadseeraz]

I didn't try it... but why does 142 == 142 output false? Btw, is autoboxing the process which checks "=="? I'm confused...

-blazed

check this code

Integer a = 42, b = 42;
Integer c = 3, d = 3;
System.out.println( a == 42);
System.out.println( a == b );
System.out.println( c == 3 );
System.out.println( c == d );

[JosAH]

check this code

Integer a = 42, b = 42;
Integer c = 3, d = 3;
System.out.println( a == 42);
System.out.println( a == b );
System.out.println( c == 3 );
System.out.println( c == d );

Yes, now make a and b equal to 142 and try again.

kind regards,

Jos