Basic Data Types (Characters)

Basic Data Types (Characters)

  • In Java, to store characters, char primitive data type or Character class is used.
  • Java uses Unicode to represent characters. Unicode contains an international character set. As it contains such a huge data, it has a width of 16 bits. (http://www.unicode.org).
  • This makes Java a universal programming language.
  • The range of char : 0 to 65,536
  • Declare a Character using char primitive type

char d = 'S';

  • Declare a Character using Character Class

Character c = 'S';

  • Both produces same thing:

System.out.println(c.equals(d));

This prints true as both are same.

Methods in Characters

Method

Description

Result Data Type

Example

charValue

Convert the input to int (by casting).

Same for floatValue(), doubleValue() etc.

mentioned in the method  name

Character c = 'S';

System.out.println(c.charValue());

Prints: S

compareTo

Returns the value 0 if the argument Character is equal to this Character;

A value less than 0 if this Character is numerically less than the Character argument; A value greater than 0 if this Character is numerically greater than the Character argument (unsigned comparison).

Integer

Character c = 'S';

System.out.println(c.compareTo('E'));

Prints: 14

Character c = 'S';

System.out.println(c.compareTo('Z'));

Prints: -7

equals

Returns true if the objects are the same; false otherwise.

 

Boolean

Character c = 'S';

System.out.println(c.equals('S'));
System.out.println(c.equals('Z'))

Prints:
True
false

toString

Returns the String representation of the character object

String

Character c = 'S';

System.out.println(c.toString());

Prints: S

getNumericValue

Returns the int value that the specified Unicode character represents

Integer

Character c = 'S';

System.out.println(Character.getNumericValue(c));

Prints: 28

getType

Returns a value of type int representing the character's general category.

 

Integer

Character c = 'S';

System.out.println(Character.getType(c));

Prints: 1

isAlphabetic

Returns true if the character is an alphabet. If not, then returns false.

Boolean

Character c = 'S';

System.out.println(Character.isAlphabetic(c));
Character d = '1';
System.out.println(Character.isAlphabetic(d));

Prints:
True
false

isDigit

Returns true if the character is a digit. If not, then returns false.

Boolean

Character c = 'S';

System.out.println(Character.isDigit(c));
Character d = '1';
System.out.println(Character.isDigit(d));

Prints:
False
True

isLetterOrDigit

Returns true if the character is either a digit or an alphabet. If not, then returns false.

Boolean

Character c = 'S';

System.out.println(Character.isLetterOrDigit(c));
Character d = '%';
System.out.println(Character. isLetterOrDigit (d));

Prints:
True
false

isLowerCase

Returns true if the character is a lower case alphabet. If not, then returns false.

Boolean

Character c = 's';

System.out.println(Character.isLowerCase(c));
Character d = '%';
System.out.println(Character.isLowerCase(d));

Prints:
True
false

isUpperCase

Returns true if the character is an upper case alphabet. If not, then returns false.

Boolean

Character c = 'A';

System.out.println(Character.isUpperCase(c));
Character d = '%';
System.out.println(Character.isUpperCase(d));

Prints:
True
false

isSpaceChar

Returns true if the character is a Space. If not, then returns false.

Boolean

Character d = ' ';

System.out.println(Character.isSpaceChar(d));

Prints:
True

toUpperCase

Converts character to upper case

Character

Character c = 'a';

System.out.println(Character.toUpperCase(c));

Prints:
A

toLowerCase

Converts character to lower case

Character

Character d = 'H';

System.out.println(Character.toLowerCase(d));

Prints:
h

isWhiteSpace

Returns true if passed character is really a white space.

Boolean

Character a = ' ';
Character b = 'S';
Character c = '\n';   

System.out.println(Character.isWhitespace(a));
System.out.println(Character.isWhitespace(b));
System.out.println(Character.isWhitespace(c));

Prints:
True
False
true

Escape Characters in Java Characters

Sometime we can provide input to Java characters in a program which can be special characters like: new line, new tab, quotation marks etc. For those special characters, we need to make the compiler understand what they actually mean. Usually we use a back slash (\) as an escape sequence in that scenario.

Here is the actual table for the special characters that we need to handle carefully and differently in Java.

Escape Sequence

Meaning

\n

New Line

\t

New Tab

\b

Backspace

\’

Single Quote

\”

Double Quote

\\

Back Slash

\r

Carriage Return

\f

Form feed

Increase Char value

Though char is mainly used for handling characters, value of char can be increased by using simple + operator.

Example:

public static void main(String[] args) 
{
	Character a = 'A';
	System.out.println(a);
	a++;
	System.out.println(a);
}

Output:

A
B

Java Booleans

Boolean has only 2 possible values: true or false. And, it has very small number of methods associated with it. We have created a sample java program to describe the methods that are associated with Boolean variables in Java.

public static void main(String[] args) 
{
	Boolean a = true;
	
	System.out.println(a.toString()); // converts boolean variable to String
		
	System.out.println(a.compareTo(false)); // compares one boolean variable to another
		
	System.out.println(a.booleanValue()); // get a boolean value from a boolean variable
		
	System.out.println(Boolean.parseBoolean("false")); // take a string and if it is in a  format convert it to a boolean variable

}
The output is:

true
1
true
false


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