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Java - Strings Class

Strings, which are widely used in Java programming, are a sequence of characters. In Java programming language, strings are treated as objects.

The Java platform provides the String class to create and manipulate strings.

Creating Strings

The most direct way to create a string is to write –

String greeting = "Hello world!";

Whenever it encounters a string literal in your code, the compiler creates a String object with its value in this case, "Hello world!'.

As with any other object, you can create String objects by using the new keyword and a constructor. The String class has 11 constructors that allow you to provide the initial value of the string using different sources, such as an array of characters.

String Methods

Here is the list of methods supported by String class –

Method

Description

Return Type

charAt()

Returns the character at the specified index (position)

char

codePointAt()

Returns the Unicode of the character at the specified index

int

codePointBefore()

Returns the Unicode of the character before the specified index

int

codePointCount()

Returns the Unicode in the specified text range of this String

int

compareTo()

Compares two strings lexicographically

int

compareToIgnoreCase()

Compares two strings lexicographically, ignoring case differences

int

concat()

Appends a string to the end of another string

String

contains()

Checks whether a string contains a sequence of characters

boolean

contentEquals()

Checks whether a string contains the exact same sequence of characters of the specified CharSequence or StringBuffer

boolean

copyValueOf()

Returns a String that represents the characters of the character array

String

endsWith()

Checks whether a string ends with the specified character(s)

boolean

equals()

Compares two strings. Returns true if the strings are equal, and false if not

boolean

equalsIgnoreCase()

Compares two strings, ignoring case considerations

boolean

format()

Returns a formatted string using the specified locale, format string, and arguments

String

getBytes()

Encodes this String into a sequence of bytes using the named charset, storing the result into a new byte array

byte[]

getChars()

Copies characters from a string to an array of chars

void

hashCode()

Returns the hash code of a string

int

indexOf()

Returns the position of the first found occurrence of specified characters in a string

int

intern()

Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index

String

isEmpty()

Checks whether a string is empty or not

boolean

lastIndexOf()

Returns the position of the last found occurrence of specified characters in a string

int

length()

Returns the length of a specified string

int

matches()

Searches a string for a match against a regular expression, and returns the matches

boolean

offsetByCodePoints()

Returns the index within this String that is offset from the given index by codePointOffset code points

int

regionMatches()

Tests if two string regions are equal

boolean

replace()

Searches a string for a specified value, and returns a new string where the specified values are replaced

String

replaceFirst()

Replaces the first occurrence of a substring that matches the given regular expression with the given replacement

String

replaceAll()

Replaces each substring of this string that matches the given regular expression with the given replacement

String

split()

Splits a string into an array of substrings

String[]

startsWith()

Checks whether a string starts with specified characters

boolean

subSequence()

Returns a new character sequence that is a subsequence of this sequence

CharSequence

substring()

Extracts the characters from a string, beginning at a specified start position, and through the specified number of character

String

toCharArray()

Converts this string to a new character array

char[]

toLowerCase()

Converts a string to lower case letters

String

toString()

Returns the value of a String object

String

toUpperCase()

Converts a string to upper case letters

String

trim()

Removes whitespace from both ends of a string

String

valueOf()

Returns the primitive value of a String object

String

 

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