CODEWITHSUNDEEP
java
James Raitsev
James Raitsev

Reputation: 96581

Getting intValue from Integer, does it make any sense?

I am looking through the code someone wrote a while back and wondering whether I am missing something here

Assuming

List<Integer> runUids = new ArrayList<Integer>();

and later on as part of a loop

int runUID = runUidsAL.get(i).intValue();

Is there any reason why intValue() needs to be called here?. Don't think it's needed here. Do you?

Upvotes: 6

Views: 23133

Answers (6)

Alex
Alex

Reputation: 480

A real situation that I have lived a few minutes ago:

I have a list of Integer objects. Each Integer is the index of an other list whose positions I want to remove.

Then... I was doing that:

for (Integer index : positionsToRemoveList) {

   historyRecord.remove(index);
}

Java was calling to the next method

public boolean remove(Object object);

Instead of:

public E remove(int location);

My "historyRecord" List wasn't being updated beacuse Java was trying to remove by an Object instead of by position.

The right way is:

for (Integer index : positionsToRemoveList) {

   historyRecord.remove(index.intValue());
}

And this is my real story : )

Upvotes: 3

Zip184
Zip184

Reputation: 1890

It's there because Integer extends Number.

Number n = new Integer(5);

int i = n.intValue();

That second line may need an int value from n, and may not know if n was instantiated with an Integer or Double.

Upvotes: 2

Gilad Novik
Gilad Novik

Reputation: 4614

Integer is an object, while int is a primitive.

intValue() method converts between the Integer class to its primitive representation.

http://mindprod.com/jgloss/intvsinteger.html

Upvotes: 1

Diego
Diego

Reputation: 18379

Java 1.5 and above supports automatic boxing and unboxing, which mans you can assign an Integer to an int without using .intValue().

Upvotes: 1

Jesper
Jesper

Reputation: 207016

You didn't say so, but I assume that runUID is an int.

It's not necessary to call intValue() explicitly on the Integer object returned by runUidsAL.get(i); Java will do this automatically by auto-unboxing.

Upvotes: 11

belgther
belgther

Reputation: 2534

You can assign an int to a long, but not an Integer object, for example. On the other hand, the intValue() could give a NullPointerException if the Integer object is null.

Upvotes: 0

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