Strings in java

Character Functions

Conversions to Ascii

String functions

Primitive data types

In this chapter

Each character is assigned to ascii

code

Character Functions

Character.isWhiteSpace()

Character.isLetterOrDigit()

Character.isUpperCase()Character.isLetter()Character.isDigit()

Character.isLowerCase()

Character.toLowerCase()Character.toUpperCase()

These functions deal only with character manipulation

Character.isLetter()

Enter a letter :

The entered character is a letter

A

This function checks whether the entered character is a letter or not

It return boolean value True or False

Enter a letter :

The entered character is a digit

3

This function checks whether the entered character is a number or not

It return boolean value True or False

Character.isDigit()

Enter a letter :

The entered character is a letter

A

This function checks whether the entered character is a letter or a digit.

It may be both

It return boolean value True or False

Character.isLetterOrDigit()

Enter a digit : 3

The entered character is a digit

Enter a letter :

There is a white space

( )

This function checks whether There is a blank space

It return boolean value True or False

Character.isWhiteSpace()

Enter a letter :

The entered character is in uppercase

A

This function checks whether the entered character is capital letter or not

It return boolean value True or False

Character.isUpperCase()

Enter a letter :

The entered character is a letter

d

This function checks whether the entered character is a lower case letter or not

It return boolean value True or False

Character.isLowerCase()

Enter a letter :

The character after conversion is a

A

This function converts the capital letter to small letter

Character.toLowerCase()

Enter a letter :

The character after conversion is H

h

This function converts the lower case letters to upper case

Character.toUpperCase()

Program to implement character function

class first{void main(char p){if(Character.isLetter(p)

System.out.println(p+ “ is a letter”);else

System.out.println(p+ “ is not a letter”);}}

class first{void main(char p){if(Character.isDigit(p)

System.out.println(p+ “ is a Digit”);else

System.out.println(p+ “ is not a Digit”);}}

class first{void main(char p){if(Character.isLetterOrDigit(p)

System.out.println(p+ “ is a letter or digit”);else

System.out.println(p+ “ is not a letter or digit”);}}

class first{void main(char p){if(Character.isUpperCase(p)

System.out.println(p+ “ is an UpperCase”);else

System.out.println(p+ “ is not an Upper Case”);}}

class first{void main(char p){if(Character.isLowerCase(p)

System.out.println(p+ “ is a LowerCase”);else

System.out.println(p+ “ is not a lower Case”);}}

class first{void main(char p){char x =Character.toUpperCase(p);System.out.println(“ The character after conversion is ” + x);}}

class first{void main(char p){char x =Character.toLowerCase(p);System.out.println(“ The character after conversion is ” + x);}}

Conversions to

Ascii

•

Computer deals with 256 characters to perform any task

Each character is specified with a numeric code called ASCII code which ranges from 0 to 255

ASCII codes

CHARACTERS ASCII CODES

0-9 48-57

A-Z 65-90

a-z 97-122

Examples how to use ASCII

char p = ‘A’;int n = (int)p;

This will give the output as 65 because the ASCII value of A is 65

Examples how to use ASCII

int x = 91;char c = (char) x;

This will give the output as b

B= 66

66+32 = 98

Hence 98 is b

The difference between ASCII code of an upper case and the corresponding lower case is 32

Procedure to convert from uppercase to lower case

Get the ASCII code of upper case character

Increase ASCII code by 32

Obtain character corresponding to the increased ASCII code

Procedure to convert from lowercase to upper case

Get ASCII code of lower case character

Decrease ASCII code by 32

Obtain character corresponding to the decreased ASCII code

String functions

String Functions

lastIndexOf()

indexOf()

Sudstring()

length()

charAt()

toLowerCase()

toUpperCase()

Replace()

These functions deal with strings

equals()

Concat()

equalsIgnoreCase()

compareTo()

trim()

endswith()

startswith()

length()

This is used to find the length of the given string

Syntax:

int var = string var.length();

Ex

String s = “COMPUTER”;Int l = s.length();System.out.println(l);

The output will be 8

charAt()

This is used to find the character at a particular position of the given string

Syntax:

char var = string var.charAt(index);

Ex

String s = “COMPUTER”;char c = s.charAt(3);System.out.println(c);

The output will be P