# Dan's - Math.abs Question..

Samy Venkat

Greenhorn

Posts: 10

posted 12 years ago

Hi Dan,

For the below program why 'f' is also included in the answer.

Which of the following statements are true in terms of the java.lang.Math.abs method?

a. Four overloaded versions of abs exist.

b. An ArithmeticException is declared in the throws clause.

c. The type of the return value depends on the type of the argument.

d. The returned value is always of a floating-point primitive type.

e. If the argument is greater than or equal to zero then the returned value is equal to the argument.

f. If the argument, arg, is less than zero then the returned value is -arg.

Thx

For the below program why 'f' is also included in the answer.

Which of the following statements are true in terms of the java.lang.Math.abs method?

a. Four overloaded versions of abs exist.

b. An ArithmeticException is declared in the throws clause.

c. The type of the return value depends on the type of the argument.

d. The returned value is always of a floating-point primitive type.

e. If the argument is greater than or equal to zero then the returned value is equal to the argument.

f. If the argument, arg, is less than zero then the returned value is -arg.

Thx

Anupam Sinha

Ranch Hand

Posts: 1090

Yi Meng

Ranch Hand

Posts: 270

posted 12 years ago

quote from api

As you can see here for negative values, their negation will be returned. And specially for Integer.MIN_VALUE, its negation is just the same as itself and so is Long.MIN_VALUE.

It could be wrong also if the statement is changed to:

public static int abs(int a)Returns the absolute value of an int value. If the argument is not negative, the argument is returned. If the argument is negative, the negation of the argument is returned.

Note that if the argument is equal to the value of Integer.MIN_VALUE, the most negative representable int value, the result is that same value, which is negative.

As you can see here for negative values, their negation will be returned. And specially for Integer.MIN_VALUE, its negation is just the same as itself and so is Long.MIN_VALUE.

It could be wrong also if the statement is changed to:

The value returned is always non-negative.

Meng Yi

Jim Kirkby

Greenhorn

Posts: 4

Dan Chisholm

Ranch Hand

Posts: 1865

posted 12 years ago

The source code for the Math.abs method is as follows.

In my opinion, it is always correct to say the following.

In my opinion, the fact that the negation of negative infinity is the same as negative infinity doesn't violate the above quote.

Originally posted by Jim Kirkby:

So the option 'f' shouldn't be true 'cause for the Integer.MIN_VALUE and Long.MIN_VALUE, the pass-in parameter and return value are the same, both negative. Right?

The source code for the Math.abs method is as follows.

In my opinion, it is always correct to say the following.

If the argument, arg, is less than zero then the returned value is -arg.

In my opinion, the fact that the negation of negative infinity is the same as negative infinity doesn't violate the above quote.

Dan Chisholm<br />SCJP 1.4<br /> <br /><a href="http://www.danchisholm.net/" target="_blank" rel="nofollow">Try my mock exam.</a>

Andres Gonzalez

Ranch Hand

Posts: 1561

posted 12 years ago

I had the same confusion

here...

here...

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