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Character Of Methods in Java
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| Java - Characters Of Methods Introduction |
In Java, the Character class provides useful methods to perform various operations
on character (char) values. These methods help determine character types
(letters, digits, whitespace, etc.), change case, and convert characters to
strings.
Let's explore some essential Character methods:
1. Checking Character Types
isLetter()
This method checks whether a character
is a letter (A-Z or a-z). It returns true if
the character is an alphabet, otherwise false.
Example:
class CharacterCheck { public static void main(String[] args) { char letter = 'G'; char digit = '8'; System.out.println(Character.isLetter(letter)); System.out.println(Character.isLetter(digit)); }}
Output:
true false
isDigit()
This method checks if a character is a
digit (0-9).
Example:
java class CharacterCheck { public static void main(String[] args) { char num1 = '5'; char letter = 'B'; System.out.println(Character.isDigit(num1)); System.out.println(Character.isDigit(letter)); }}
Output:
true false
isWhitespace()
Checks if a character is a whitespace
(spaces, tabs, etc.).
Example:
class WhitespaceCheck { public static void main(String[] args) { char space = ' '; char letter = 'X'; System.out.println(Character.isWhitespace(space)); System.out.println(Character.isWhitespace(letter)); }}
Output:
true false 2. Checking Uppercase & Lowercase Characters
isUpperCase()
Checks if a character is uppercase
(A-Z).
Example:
class CaseCheck { public static void main(String[] args) { char upper = 'M'; char lower = 'm'; System.out.println(Character.isUpperCase(upper)); System.out.println(Character.isUpperCase(lower)); }}
Output:
true false
isLowerCase()
Checks if a character is lowercase
(a-z).
Example:
class CaseCheck { public static void main(String[] args) { char lower = 'p'; char upper = 'P'; System.out.println(Character.isLowerCase(lower)); System.out.println(Character.isLowerCase(upper)); }}
Output:
true false 3. Converting Characters
toUpperCase()
Converts a lowercase letter to
uppercase. If the character is already uppercase or not a letter, it remains
unchanged.
Example:
class ConvertCase { public static void main(String[] args) { char lower = 'b'; char symbol = '@'; System.out.println(Character.toUpperCase(lower)); System.out.println(Character.toUpperCase(symbol)); }}
Output:
B @ toLowerCase()
Converts an uppercase letter to
lowercase. Other characters remain unchanged.
Example:
class ConvertCase { public static void main(String[] args) { char upper = 'R'; char number = '7'; System.out.println(Character.toLowerCase(upper)) System.out.println(Character.toLowerCase(number)); }}
Output:
r 7
4. Converting Character to String
toString()
Converts a char
into a String.
Example:
class CharToString { public static void main(String[] args) { char ch = 'Z'; String str = Character.toString(ch); System.out.println(str); System.out.println(str.getClass().getSimpleName()); }}
Output:
Z String
Common Mistakes to Avoid
Using Strings instead of characters in
Character methods
String str = "A"; System.out.println(Character.toUpperCase(str));
Correct
char ch = 'A'; System.out.println(Character.toUpperCase(ch));
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