How to convert int to Integer

Question

private static HashMap<Integer, Bitmap> mBitmapCache;         
mBitmapCache.put(R.drawable.bg1,object);

R.drawable.bg1 is an int ... but i want to convert into Integer because Hashmap takes an Integer... and when draw the multiple objects in seconds , it creates a Integer Object runtime which affects the performence of the code...

Olegas · Answer 1 · 2021-03-01T08:29:55.213

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int iInt = 10;
Integer iInteger = Integer.valueOf(iInt);

P.S. Answer edited due to comments pointing out an issue with initial suggested solution.

edited Mar 01 '21 at 08:29

answered Mar 25 '11 at 06:34

Olegas

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"You should not call the constructor for wrapper classes directly, such as`new Integer(42)`. Instead, call the valueOf factory method, such as Integer.valueOf(42). This will typically use less memory because common integers such as 0 and 1 will share a single instance." Integer iInteger = Integer.valueOf(iInt); – user3439968 Oct 03 '15 at 15:01
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i think this is done automatically, thus you could have somethink like `Integer iInteger = iInt;` and it should work. – Ionut Negru Sep 22 '16 at 13:34
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I just wanted to share https://stackoverflow.com/q/3131136/384674 for "You should not call constructor..." – Betlista Dec 15 '18 at 20:14
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Just for curiosity, is `Integer value = (Integer) intValue;` a bad practise? Or, it's not recommended for int to Integer conversion? – Simon Z. Mar 20 '19 at 01:32
It is bad practice to convert it through the wrapper classes directly. – Simran Sharma Mar 01 '21 at 07:11
@SimranSharma you are wrong see this question:https://stackoverflow.com/questions/67088328/directly-casting-primitive-type-to-object-is-fine-in-java – Chaitanya Karmarkar Apr 14 '21 at 08:55
@ChaitanyaKarmarkar, I guess you haven't seen the edits to this answer. The older answer used the constructor of the wrapper class to convert it. Somewhat like this `new Integer(int);`. Using wrapper class in this way to cast is a bad practice. You should use `Integer.valueOf(int)` instead. It is a function built for this purpose and is more reliable and efficient. – Simran Sharma Apr 17 '21 at 03:56
@SimranSharma You are correct about new Integer(int); This one is bad practice. But Integer value = (Integer) intValue; is not a bad practice. It is Autoboxing that is what I want to say. – Chaitanya Karmarkar Apr 17 '21 at 12:41
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@ChaitanyaKarmarkar, absolutely that is not a bad practice. I said it because, in the previous edit, he used `new Integer(int);`. But, I feel when there is a method that is provided dedicated for one purpose, it always makes more sense to use the method instead. I feel it always works out to be more efficient that way (in general, not being specific to Integer casting). – Simran Sharma Apr 17 '21 at 12:47
I agree with you. – Chaitanya Karmarkar Apr 19 '21 at 12:19

score 26 · Answer 2 · edited Mar 02 '21 at 00:42

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As mentioned, one way is to use

int original = 32;
Integer converted = new Integer(original);

But you should not call the constructor for wrapper classes directly. It is a poor practice to do so. Instead, use the methods pre-defined especially for this purpose.

So, the new code would look like this (recommended):

mBitmapCache.put(Integer.valueOf(R.drawable.bg1), object);

edited Mar 02 '21 at 00:42

Simran Sharma

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answered Apr 25 '17 at 22:33

Morphing Coffee

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Is there a reason "you should not call the constructor for wrapper classes directly"? – Jacob Holloway Apr 25 '17 at 22:56
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Not really - it is just a guess that the dev did not have an urge to create new object on every call. Rarely the case: You would use new Integer() if you want to distinguish several Integer objects. Mostly the case: You are using Integer and not int just because you want to also have *null* value. Integer.valueOf() would return you the same object on multiple calls in particular scenario, which will save memory (never the case with new Integer()). – Morphing Coffee Apr 26 '17 at 00:14
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I just wanted to share https://stackoverflow.com/q/3131136/384674 for "You should not call constructor..." – Betlista Dec 15 '18 at 20:14

score 1 · Answer 3 · answered Mar 25 '11 at 09:01

I had a similar problem . For this you can use a Hashmap which takes "string" and "object" as shown in code below:

/** stores the image database icons */
public static int[] imageIconDatabase = { R.drawable.ball,
        R.drawable.catmouse, R.drawable.cube, R.drawable.fresh,
        R.drawable.guitar, R.drawable.orange, R.drawable.teapot,
        R.drawable.india, R.drawable.thailand, R.drawable.netherlands,
        R.drawable.srilanka, R.drawable.pakistan,

};
private void initializeImageList() {
    // TODO Auto-generated method stub
    for (int i = 0; i < imageIconDatabase.length; i++) {
        map = new HashMap<String, Object>();

        map.put("Name", imageNameDatabase[i]);
        map.put("Icon", imageIconDatabase[i]);
    }

}

score 0 · Answer 4 · answered Mar 01 '21 at 07:04

One of the way is by using following
Integer obj = new Integer(primitiveValue) or in your case new Integer(R.drawable.bg1). The only problem with this is it would unnecessarily create an objects during runtime.

If you are using JDK 5 or above you can exercise power of Autoboxing.
Lets keep that aside for a while.

Within class Integer (java.lang.Integer) we do have many methods one of which is:
static Integer valueOf(int) it returns value of an int as a Integer.

So a Integer.valueOf(R.drawable.bg1) could work.

score -4 · Answer 5 · edited Jan 22 '17 at 00:46

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i it integer, int to Integer

Integer intObj = new Integer(i);

add to collection

list.add(String.valueOf(intObj));

edited Jan 22 '17 at 00:46

ppasler

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answered Jan 21 '17 at 19:20

IvanT

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When your trying to answer a question which has is already being answered. Add more information to the answer so that it adds value. – Vishnu667 Jan 21 '17 at 19:49

How to convert int to Integer

5 Answers5