This has probably been answered else where but how do you get the character value of an int value?
Specifically I'm reading a from a tcp stream and the readers .read() method returns an int.
How do I get a char from this?
12 Answers
Maybe you are asking for:
Character.toChars(65) // returns ['A']
More info: Character.toChars(int codePoint)
Converts the specified character (Unicode code point) to its UTF-16 representation stored in a char array. If the specified code point is a BMP (Basic Multilingual Plane or Plane 0) value, the resulting char array has the same value as codePoint. If the specified code point is a supplementary code point, the resulting char array has the corresponding surrogate pair.
3 Comments
Jon Skeet
That's only valid if the integer in question is already a UTF-16 code point. We have no idea whether that's the case.
Jon Skeet
@Atec: No, my point is that if he's just reading bytes from a stream (it's not clear) then converting by just casting or using
toChars is usually inappropriate. If he's reading from a Reader, then it's fine.
ArtOfWarfare
While admittedly the question didn't specify it, this question comes up as the first result in a Google search for converting ASCII code points to chars, so I'm upvoting it.
It depends on what you mean by "convert an int to char".
If you simply want to cast the value in the int, you can cast it using Java's typecast notation:
int i = 97; // 97 is 'a' in ASCII
char c = (char) i; // c is now 'a'
If you mean transforming the integer 1 into the character '1', you can do it like this:
if (i >= 0 && i <= 9) {
char c = Character.forDigit(i, 10);
....
}
If you're trying to convert a stream into text, you need to be aware of which encoding you want to use. You can then either pass an array of bytes into the String constructor and provide a Charset, or use InputStreamReader with the appropriate Charset instead.
Simply casting from int to char only works if you want ISO-8859-1, if you're reading bytes from a stream directly.
EDIT: If you are already using a Reader, then casting the return value of read() to char is the right way to go (after checking whether it's -1 or not)... but it's normally more efficient and convenient to call read(char[], int, int) to read a whole block of text at a time. Don't forget to check the return value though, to see how many characters have been read.
5 Comments
Vanuan
I think this is not what the OP is asking about. He is using Reader's read method: java.sun.com/j2se/1.4.2/docs/api/java/io/Reader.html#read() The question he is asking is how to convert value returned by this method into char.
Jon Skeet
If he's genuinely using Reader, that certainly makes a difference. It's not clear, given that he talks about a stream and a reader (with a lower case r) in the same sentence :( Have edited my answer to make this clear.
bvdb
you can also wrap the
InputStreamReader in a BufferedReader, as mentioned in the javadoc docs.oracle.com/javase/8/docs/api/java/io/…
Sébastien
Why is it that "Simply casting from int to char only works if you want ISO-8859-1" ? Is it because Java uses UTF-16 internally, and all ISO-8859-1 characters keep the same code unit (bits) in UTF-16 ?
Jon Skeet
@Sebastien: Yes, that's basically it.
If you want to simply convert int 5 to char '5': (Only for integers 0 - 9)
int i = 5;
char c = (char) ('0' + i); // c is now '5';
3 Comments
toddkaufmann
No.. '0' + 5 becomes the string '05'. Right-hand side should be (char) ((int) '0') + i;
Kaushik Shankar
Not true because characters don't get converted to Strings in Java.
Ian Campbell
+1 -- tried and tested, it works! Try and test it yourself, seemingly unlike the commenters here...
Simple casting:
int a = 99;
char c = (char) a;
Is there any reason this is not working for you?
4 Comments
sleske
Dangerous advice, if the text stream is not pure ASCII. See Jon Skeet's answer above.
Vanuan
It might not work. But I think it would actually. The char data type stores UTF-16 coded value. So to cast char to int you need to do some transformations. But since the OP uses read() method which already returns UTF-16 coded value simple casting would work I think. Correct me if I wrong.
Vanuan
Sorry, I meant "from int to char"
Vasil Valchev
this will cause unexpected encoding values, not numbers
This solution works for Integer length size =1.
Integer input = 9;
Character.valueOf((char) input.toString().charAt(0))
if size >1 we need to use for loop and iterate through.
Comments
Most answers here propose shortcuts, which can bring you in big problems if you have no idea what you are doing. If you want to take shortcuts, then you have to know exactly what encoding your data is in.
UTF-16
Whenever java talks about characters in its documentation, it talks about 16-bit characters.
You can use a DataInputStream, which has convenient methods. For efficiency, wrap it in a BufferedReader.
// e.g. for sockets
DataInputStream in = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
char character = readChar(); // no need to cast
The thing is that each readChar() will actually perform 2 read's and combine them to one 16-bit character.
US-ASCII
US-ASCII reserves 8 bits to encode 1 character. The ASCII table only describes 128 possible characters though, so 1 bit is always unused.
You can simply perform a cast in this case.
int input = stream.read();
if (input < 0) throw new EOFException();
char character = (char) input;
Extended ASCII
UTF-8, Latin-1, ANSI and many other encodings use all 8-bits. The first 7-bit follow the ASCII table and are identical to the ones of the US-ASCII encoding. However, the 8th bit offers characters that are different in all these encodings. So, here things get interesting.
If you are a cowboy, and you think that the 8th bit does not matter (i.e. you don't care about characters like "à, é, ç, è, ô ...) then you can get away with a simple cast.
However, if you want to do this professionally, you should really ALWAYS specify a charset whenever you import/export text (e.g. sockets, files ...).
Always use charsets
Let's get serious. All the above options are cheap tricks. If you want to write flexible software you need to support a configurable charset to import/export your data. Here's a generic solution:
Read your data using a byte[] buffer and to convert that to a String using a charset parameter.
byte[] buffer = new byte[1024];
int nrOfBytes = stream.read(buffer);
String result = new String(buffer, nrOfBytes, charset);
You can also use an InputStreamReader which can be instantiated with a charset parameter.
Just one more golden rule: don't ever directly cast a byte to a character. That's always a mistake.
Comments
Basing my answer on assumption that user just wanted to literaaly convert an int to char , for example
Input:
int i = 5;
Output:
char c = '5'
This has been already answered above, however if the integer value i > 10, then need to use char array.
char[] c = String.valueOf(i).toCharArray();
Comments
int i = 7;
char number = Integer.toString(i).charAt(0);
System.out.println(number);
Comments
maybe not the fastest one:
//for example there is an integer with the value of 5:
int i = 5;
//getting the char '5' out of it:
char c = String.format("%s",i).charAt(0);
Comments
The answer for conversion of char to int or long is simple casting.
For example:- if you would like to convert Char '0' into long.
Follow simple cast
Char ch='0';
String convertedChar= Character.toString(ch); //Convert Char to String.
Long finalLongValue=Long.parseLong(convertedChar);
Done!!
1 Comment
specializt
thats EXACTLY the opposite of what he was asking.
public int read(char[] cbuf)will solve the problem?