Wrapper types comparison doubt

[Kedar Pethe]

Chapter 6, Self test Q3.

class TKO {
  public static void main(String[] args) {
    String s = "-";
    Integer x = 343;
    long L343 = 343L;
    if(x.equals(L343))  s += ".e1 ";
    if(x.equals(343))  s += ".e2 "; 
    Short s1 = (short)((new Short((short)343)) / (new Short((short)49)));
    if(s1 == 7)        s += "=s "; 
    if(s1 < new Integer(7+1))  s += "fly ";
    System.out.println(s);
  }

Which of the following will be included in the output String s? (Choose all that apply.)
  A.  .e1
   B.  .e2
   C.  =s
   D.  fly
   E. None of the above
   F. Compilation fails
   G. An exception is thrown at runtime
}

Correct answers - B,C,D

How come answer is also D option??
I know that two Integer wrapper objects can be compared.

Using simple relational operator,
How can a short object be compared with an Integer object?
How does Java compare the two different wrapper's values??

[Henry Wong]

Kedar Pethe wrote:Chapter 6, Self test Q3.

class TKO {
  public static void main(String[] args) {
    String s = "-";
    Integer x = 343;
    long L343 = 343L;
    if(x.equals(L343))  s += ".e1 ";
    if(x.equals(343))  s += ".e2 "; 
    Short s1 = (short)((new Short((short)343)) / (new Short((short)49)));
    if(s1 == 7)        s += "=s "; 
    if(s1 < new Integer(7+1))  s += "fly ";
    System.out.println(s);
  }

Which of the following will be included in the output String s? (Choose all that apply.)
  A.  .e1
   B.  .e2
   C.  =s
   D.  fly
   E. None of the above
   F. Compilation fails
   G. An exception is thrown at runtime
}

Correct answers - B,C,D

How come answer is also D option??
I know that two Integer wrapper objects can be compared.

Using simple relational operator,

How can a short object be compared with an Integer object?
How does Java compare the two different wrapper's values??

The answer is .... it depends.

If you are using a "==" or "!=" as the operator, it will do an instance comparison, meaning whether the two instances are the same instance.... and of course, this will fail to compile as Short and Integer are not sub/super classes of each other.

Otherwise, such as what you did in the example, it will do a value comparison, meaning it will unbox both sides first.

Henry

[Kedar Pethe]

Henry Wong wrote:
If you are using a "==" or "!=" as the operator, it will do an instance comparison, meaning whether the two instances are the same instance.... and of course, this will fail to compile as Short and Integer are not sub/super classes of each other.
Otherwise, such as what you did in the example, it will do a value comparison, meaning it will unbox both sides first.
Henry

Ok.. but is it that while using >,<,<=,>= whatever be the two wrapper types(Byte,Short,Integer,Long,Float,Double) comparison will always take place on their values??

[Kedar Pethe]

Henry Wong wrote:
If you are using a "==" or "!=" as the operator, it will do an instance comparison, meaning whether the two instances are the same instance.... and of course, this will fail to compile as Short and Integer are not sub/super classes of each other.

Otherwise, such as what you did in the example, it will do a value comparison, meaning it will unbox both sides first.

Henry

I tried, whatever be the two operands for relational operators, comparison always takes place on their values and gives correct output, without any error!!