Ascii chars in java

Ascii chars in java

This chapter specifies the lexical structure of the Java programming language.

Programs are written in Unicode (§3.1), but lexical translations are provided (§3.2) so that Unicode escapes (§3.3) can be used to include any Unicode character using only ASCII characters. Line terminators are defined (§3.4) to support the different conventions of existing host systems while maintaining consistent line numbers.

The Unicode characters resulting from the lexical translations are reduced to a sequence of input elements (§3.5), which are white space (§3.6), comments (§3.7), and tokens. The tokens are the identifiers (§3.8), keywords (§3.9), literals (§3.10), separators (§3.11), and operators (§3.12) of the syntactic grammar.

3.1. Unicode

Programs are written using the Unicode character set. Information about this character set and its associated character encodings may be found at http://www.unicode.org/ .

The Java SE platform tracks the Unicode Standard as it evolves. The precise version of Unicode used by a given release is specified in the documentation of the class Character .

Versions of the Java programming language prior to JDK 1.1 used Unicode 1.1.5. Upgrades to newer versions of the Unicode Standard occurred in JDK 1.1 (to Unicode 2.0), JDK 1.1.7 (to Unicode 2.1), Java SE 1.4 (to Unicode 3.0), Java SE 5.0 (to Unicode 4.0), Java SE 7 (to Unicode 6.0), and Java SE 8 (to Unicode 6.2).

The Unicode standard was originally designed as a fixed-width 16-bit character encoding. It has since been changed to allow for characters whose representation requires more than 16 bits. The range of legal code points is now U+0000 to U+10FFFF, using the hexadecimal U+n notation . Characters whose code points are greater than U+FFFF are called supplementary characters. To represent the complete range of characters using only 16-bit units, the Unicode standard defines an encoding called UTF-16. In this encoding, supplementary characters are represented as pairs of 16-bit code units, the first from the high-surrogates range, (U+D800 to U+DBFF), the second from the low-surrogates range (U+DC00 to U+DFFF). For characters in the range U+0000 to U+FFFF, the values of code points and UTF-16 code units are the same.

The Java programming language represents text in sequences of 16-bit code units, using the UTF-16 encoding.

Some APIs of the Java SE platform, primarily in the Character class, use 32-bit integers to represent code points as individual entities. The Java SE platform provides methods to convert between 16-bit and 32-bit representations.

This specification uses the terms code point and UTF-16 code unit where the representation is relevant, and the generic term character where the representation is irrelevant to the discussion.

Except for comments (§3.7), identifiers, and the contents of character and string literals (§3.10.4, §3.10.5), all input elements (§3.5) in a program are formed only from ASCII characters (or Unicode escapes (§3.3) which result in ASCII characters).

ASCII (ANSI X3.4) is the American Standard Code for Information Interchange. The first 128 characters of the Unicode UTF-16 encoding are the ASCII characters.

3.2. Lexical Translations

A raw Unicode character stream is translated into a sequence of tokens, using the following three lexical translation steps, which are applied in turn:

1. A translation of Unicode escapes (§3.3) in the raw stream of Unicode characters to the corresponding Unicode character. A Unicode escape of the form \u xxxx , where xxxx is a hexadecimal value, represents the UTF-16 code unit whose encoding is xxxx . This translation step allows any program to be expressed using only ASCII characters.
2. A translation of the Unicode stream resulting from step 1 into a stream of input characters and line terminators (§3.4).
3. A translation of the stream of input characters and line terminators resulting from step 2 into a sequence of input elements (§3.5) which, after white space (§3.6) and comments (§3.7) are discarded, comprise the tokens (§3.5) that are the terminal symbols of the syntactic grammar (§2.3).

The longest possible translation is used at each step, even if the result does not ultimately make a correct program while another lexical translation would. There is one exception: if lexical translation occurs in a type context (§4.11) and the input stream has two or more consecutive > characters that are followed by a non- > character, then each > character must be translated to the token for the numerical comparison operator > .

The input characters a—b are tokenized (§3.5) as a , — , b , which is not part of any grammatically correct program, even though the tokenization a , — , — , b could be part of a grammatically correct program.

Without the rule for > characters, two consecutive > brackets in a type such as List < List < String >> would be tokenized as the signed right shift operator >> , while three consecutive > brackets in a type such as List < List < List < String >> > would be tokenized as the unsigned right shift operator >>> . Worse, the tokenization of four or more consecutive > brackets in a type such as List < List < List < List < String >> > > would be ambiguous, as various combinations of > , >> , and >>> tokens could represent the > > > > characters.

3.3. Unicode Escapes

A compiler for the Java programming language («Java compiler») first recognizes Unicode escapes in its input, translating the ASCII characters \u followed by four hexadecimal digits to the UTF-16 code unit (§3.1) for the indicated hexadecimal value, and passing all other characters unchanged. Representing supplementary characters requires two consecutive Unicode escapes. This translation step results in a sequence of Unicode input characters.

Источник

How to get the ASCII value of a character in Java

Many candidates are rejected or down-leveled in technical interviews due to poor performance in behavioral or cultural fit interviews. Ace your interviews with this free course, where you will practice confidently tackling behavioral interview questions.

What are ASCII values?

ASCII assigns letters, numbers, characters, and symbols a slot in the 256 available slots in the 8-bit code.

Character	ASCII value
a	97
b	98
A	65
B	66

Cast char to int

Cast a character from the char data type to the int data type to give the ASCII value of the character.

Code

In the code below, we assign the character to an int variable to convert it to its ASCII value.

public class Main  
public static void main(String[] args)  
char ch = 'a';
 
int as_chi = ch;
 
System.out.println("ASCII value of " + ch + " is - " + as_chi);
 
>
>

In the code below, we print the ASCII value of every character in a string by casting it to int .

public class Main  
public static void main(String[] args)  
String alphabets = "abcdjfre";
 
for(int i=0;ichar ch = alphabets.charAt(i);
 
System.out.println("ASCII value of " + ch + " is - " + (int)ch);
 
>
 
>
>

Learn in-demand tech skills in half the time

Источник

How to Convert an ASCII Code to char in Java?

ASCII is the abbreviation of “American Standard Code for Information Interchange”. A computer knows the language in numeric form. Therefore, ASCII is used to communicate with computers by exchanging information. All keyboard characters, including all alphabets, numbers, and special characters, comprise a unique ASCII code that the computer understands to process the typed key.

This blog will discuss converting an ASCII code to a character in Java.

How to Convert an ASCII Code to char in Java?

For converting an ASCII code to a character in Java, there are different methods listed below:

Let’s check the functionality of each of these methods with examples.

Method 1: To Convert an ASCII Code to char Using Type Casting

Most programmers utilize Type Casting for converting an ASCII code to char in a Java program as it directly converts one data type to another.

Syntax
The syntax for converting ASCII Code to char in Java using the Type Casting method is given as:

“ascii” is the variable that stores a value of data type “int”. The keyword “char” with the parenthesis like “(char)” indicates that the mentioned int type “ascii” variable is typecasted into a character, and the resultant value will be stored in “asciiToChar”.

Let’s check out an example to understand the conversion of ASCII code to char using Type Casting.

Example
Here, we have an integer type variable “ascii” initialized with “69”:

Now, we will convert the created variable to a character using Type Casting:

Lastly, we will print the resultant character “ascii”:

The output indicates that the ASCII code “69” is converted to “E” char:

Let’s check some other methods to convert the ASCII code to char in Java.

Method 2: To Convert an ASCII Code to char Using toString()

The Java wrapper class named “Character” also offers a “toString()” method, which allows us to convert an ASCII code to the string representing the character’s value.

Here, “ascii” is an “int” type data variable containing ASCII code that will be converted to a string referring to the corresponding character.

Example
In this example, we have an ASCII value “75” stored in “ascii”:

We will call the “Character.toString()” method by passing the created character as a parameter and then store the returned value in “asciiToChar” String type variable. Now the question is why it is a String type variable, not a character type? Because the toString() method will always return a string:

Lastly, execute the “System.out.println()” method to print out the required value:

As you can see, the given program successfully converted “75” ASCII code to the “K” character:

We have one more method to perform the same operation. So, move to the next section!

Method 3: To Convert an ASCII Code to char Using toChars()

The “toChars()” method of the Character wrapper class can also be utilized to convert an ASCII code to char in a Java program. It returns the output as an array of characters.

Here, “ascii” is an integer type variable having ASCII code that is passed to the “Character.toChars()” method. This method will return a character array.

Example
Firstly, we will create a variable named “ascii” having “116” as ASCII code:

Then, we will call the “Character.toChars()” method, pass “ascii” as an argument, and store the returned char array in “asciiToChar”:

Lastly, we will print the output on the console:

System . out . print ( «Ascii » + ascii + » is a value of Character: » ) ;
System . out . println ( asciiToChar ) ;

We presented the easiest methods to convert ASCII code to char in Java.

Conclusion

To convert ASCII code to a character, you can use different methods such as Type Casting, toString() method, and toChars() method of the Character class. The toString() method will return a character as a String, while the toChars() method returns the array of characters. Type Casting is the most common and easy method to convert an ASCII code to a character, as it directly typecasts the ASCII code to char. This blog discussed the methods used to convert an ASCII code to char in Java.

About the author

Farah Batool

I completed my master’s degree in computer science. I am an academic researcher and love to learn and write about new technologies. I am passionate about writing and sharing my experience with the world.

Источник