Difference between String.valueOf() and new String()

Question

What is the difference between String.valueOf() and new String()? When would you use one over the other?

example 1:

public String fun(){

 int foo = 55;
 return String.valueOf(foo);

}

example 2:

public String fun(){

int foo = 55;
return new String(foo);

}

Update: Yes, the second example doesn't compile as pointed out by others below. I didn't realize it because I have been using new String("something" + foo) and it has worked, as pointed out by fastcodejava. So is there a difference between the two if I use new String("something" + foo) or String.valueOf(foo) ?

Who cares? They do the same thing and both create a String object to be returned. — Michael Yaworski
– Michael Yaworski, Commented Feb 23, 2014 at 20:21
really? 3 downvotes for this question? I explained my source of confusion by updating the question. whatever. at least i'm clear about this now. — user2441441
– user2441441, Commented Feb 23, 2014 at 20:26

Rachit · Accepted Answer · 2014-02-23 20:11:56Z

2

The first method takes an integer and converts it to String. However, the second method is just a constructor that creates a new object of type String. It cannot take an integer as argument.

answered Feb 23, 2014 at 20:11

Rachit

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Comments

Mr. Polywhirl · Accepted Answer · 2014-02-23 20:12:32Z

2

There is no constructor for String that takes a single integer.

String(byte[] bytes)
String(char[] value)
String(String original)
String(StringBuffer buffer)
String(StringBuilder builder)

You should use:

Integer.toString(foo);

answered Feb 23, 2014 at 20:12

Mr. Polywhirl

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Comments

betteroutthanin · Accepted Answer · 2014-02-23 20:19:51Z

2

In example2, it should be

return new String(Integer.toString(foo));

Your one doesn't compile. So there's no need to think about the difference between them, they take different parameters.

edited Feb 23, 2014 at 20:19

answered Feb 23, 2014 at 20:12

betteroutthanin

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1 Comment

J. M. Becker Over a year ago

new is redundant, you can just return Integer.toString(foo);

fastcodejava · Accepted Answer · 2014-02-23 20:12:54Z

1

The second code won't even compile. But if you did return new String("" + foo);, it would. They are pretty much same after that.

answered Feb 23, 2014 at 20:12

fastcodejava

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3 Comments

user2441441 Over a year ago

I see. I have been using new String("something" + foo) and it works, so your answer greatly clarified things. Thank you!

kares Over a year ago

this is a pretty bad Java advice - it creates 2 unnecessary objects

Rudy Over a year ago

There is no point to do new String("" +foo); ""+foo itself is already a new String.

Yser · Accepted Answer · 2014-02-23 20:08:49Z

1

The first method tries to convert the type to String and creates a new string with that value. The second method is a constructor which just creates a new string out of a string-like format (not a typeconversion in the sense of Integer -> String).

So the comments are right...it doesnt compile :)

answered Feb 23, 2014 at 20:08

Yser

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Comments

Nitin Agrawal · Accepted Answer · 2020-07-05 08:55:32Z

1

I can't see any difference between String.valueOf() and new String() apart from the points given by others, as I see both are creating a new String object. I tried using -

    char[] chars = {'c','a','t'};
    System.out.println(String.valueOf(chars) == String.valueOf(chars));
    System.out.println(new String(chars) == new String(chars));

Both give false stating that both are different String objects.
So I don't see any performance or memory consumption difference.

edited Jul 5, 2020 at 8:55

answered Jun 28, 2020 at 15:24

Nitin Agrawal

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Comments

Krishnamurthy V · Accepted Answer · 2019-07-02 16:02:42Z

0

Strangely, the following code pieces produced different results. Looks like there is some difference when it comes to handling Base64 encoded byte[]

Incorrect:

byte[] bytesArray = new byte[(int) a_imageFile.length()];
FileInputStream fis= new FileInputStream(a_imageFile);
fis.read(bytesArray);
byte[] encoded = Base64.getEncoder().encode(bytesArray);            
result = "data:image/jpg;base64,"+ String.valueOf(encoded);

Correct:

...
result = "data:image/jpg;base64,"+ new String(encoded);

answered Jul 2, 2019 at 16:02

Krishnamurthy V

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Comments

Ayyjayy2 · Accepted Answer · 2022-06-06 16:04:11Z

0

Another example of how they differ:

When reading in files and using readAllBytes(), using new String() allows you to print the content of that file.

String template = new String(fileName.readAllBytes());
Log.info("File content: " + template;

//content of the file is logged like 'hello, this is the content of my txt file'

However, when using String.valueOf, you get the address location instead.

String template = String.valueOf(fileName.readAllBytes());
Log.info("File address: " + template;

//an address location is logged instead like 'A@24gj49bj'

answered Jun 6, 2022 at 16:04

Ayyjayy2

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