[java tutorial] Java Character class

Java Character Class

When using characters, we usually use the built-in data type char.

Examples

char ch = 'a';

// Unicode for uppercase Greek omega character
char uniChar = '\u039A'; 

// 字符数组
char[] charArray ={ 'a', 'b', 'c', 'd', 'e' };

However, in the actual development process, we often encounter situations where we need to use objects instead of built-in data types. In order to solve this problem, the Java language provides a wrapper class Character class for the built-in data type char. The

Character class provides a series of methods to manipulate characters. You can use the Character constructor to create a Character class object, for example:

Character ch = new Character('a');

In some cases, the Java compiler will automatically create a Character object.

For example, when a char type parameter is passed to a method that requires a Character type parameter, the compiler will automatically convert the char type parameter into a Character object. This feature is called boxing, and the converse is called unboxing.

Example

// Here following primitive char 'a'
// is boxed into the Character object ch
Character ch = 'a';

// Here primitive 'x' is boxed for method test,
// return is unboxed to char 'c'
char c = test('x');

Escape sequence

The character preceded by a backslash () represents an escape character, which has special meaning to the compiler.

The following list shows Java's escape sequences:

Escape Sequences

Description

t Insert a tab key in the text

b Insert a back key in the text

n Insert a line break in the text

r Insert a carriage return in the text

f Insert a page break in the text

' Insert a single quotation mark in the text

" Insert a double quotation mark in the text

\ Insert backslash in the text

Example

When the print statement encounters an escape sequence, the compiler can correctly interpret it

public class Test {

   public static void main(String args[]) {
      System.out.println("She said \"Hello!\" to me.");
   }
}

The above. The example compilation and running results are as follows:

She said "Hello!" to me.

Character method

The following are the methods of the Character class:

Serial number

Method and description

1 isLetter()
Is it a letter

2 isDigit()
Is it a numeric character

3 isWhitespace( )
is a space

4 isUpperCase()
is an uppercase letter

5 isLowerCase()
is a lowercase letter

6 toUpperCase( )
specifies the uppercase form of letters

7 toLowerCase()
specifies the lowercase form of letters

8 toString()
returns the string form of the character, the string The length is only 1

For a complete list of methods, please refer to the java.lang.Character API specification.