add method

Posted on 2011-04-26
Medium Priority
Last Modified: 2012-08-14
>>Which of the following is valid code?

1) System.out.println(Integer.toBinaryString(4));
2) System.out.println(Integer.toOctalString(4));
3) System.out.println(Integer.add(2,2));
4) Float[] ar = new Float[] { new Float(1.0), new Float(2.1)};

Answer to Question 5

1) System.out.println(Integer.toBinaryString(4));
2) System.out.println(Integer.toOctalString(4));
4) Float[] ar = new Float[] { new Float(1.0), new Float(2.1)};

The wrapper classes contain no methods for manipulating the contents as if they were primitives, thus add method in option 3 does not exist. If you want to do that you need to extract the primitive values represented and work on them.

i was going through above question from following link


It is not clear to me.

There is no add method on Integer class.

Any ideas, resources, links, sample code highly appreciated. thanks in advance.
Question by:gudii9
  • 2
LVL 47

Accepted Solution

for_yan earned 668 total points
ID: 35471949
There is no add method in Integer class
You need to get intValue() - primitive type int
and then add two numbers

LVL 92

Assisted Solution

objects earned 668 total points
ID: 35471969
Integer and other primitive wrapper classes are immutable (the same as String)
you cannot change the value
LVL 16

Assisted Solution

imladris earned 664 total points
ID: 35476618
The question is, which of the lines is valid code. The answer is that all of them are except number 3:


This is not valid code. The Integer class does *not* have an "add" method, and therefore this code will not compile. If you wanted to add to integers you would have to do it differently.
LVL 16

Expert Comment

ID: 35707109
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