Java String

string in java

A Java String is an object that represents a sequence of characters.

Example:

char[] ch={‘A’,’S’,’K’,’A’,’T’,’U’,’L’};
String s=new String(ch);

Java String class provides a lot of methods to perform operations on strings such as

compare(),
concat(),
equals(),
split(),
length(),
replace(),
compareTo(),
intern(),
substring() etc.


What is String in java:

Generally, String is a sequence of characters. But in Java, string is an object that represents a sequence of characters. The java.lang.String class is used to create a string object.


How to create a string object?

There are two ways to create String object:

  1. By string literal
  2. By new keyword

i) String Literal:

 Java String literal is created by using double quotes.

Example:

String s=”welcome”;

ii) By new keyword:

Example:

String s=new String(“Welcome”);//creates two objects and one reference variable

String Example:

public class StringExample{
public static void main(String args[]){
String s1=”java”;//creating string by java string literal
char ch[]={‘s’,’t’,’r’,’i’,’n’,’g’,’s’};
String s2=new String(ch);//converting char array to string
String s3=new String(“example”);//creating java string by new keyword
System.out.println(s1);
System.out.println(s2);
System.out.println(s3);
}}

       Java String class methods

Sr.No.    Method     Description
1.char charAt(int index)returns char value for the particular index
2.int length()returns string length
3.static String format(String format, Object… args)returns a formatted string.
4.static String format(Locale l, String format, Object… args)returns formatted string with given locale.
5.String substring(int beginIndex)returns substring for given begin index.
6.String substring(int beginIndex, int endIndex)returns substring for given begin index and end index.
7.boolean contains(CharSequence s)returns true or false after matching the sequence of char value.
8.static String join(CharSequence delimiter, CharSequence… elements)returns a joined string.
9.static String join(CharSequence delimiter, Iterable<? extends CharSequence> elements)returns a joined string.
10.boolean equals(Object another)checks the equality of string with the given object.
11.boolean isEmpty()checks if string is empty.
12.String concat(String str)concatenates the specified string.
13.String replace(char old, char new)replaces all occurrences of the specified char value.
14.String replace(CharSequence old, CharSequence new)replaces all occurrences of the specified CharSequence.
15.static String equalsIgnoreCase(String another)compares another string. It doesn’t check case.
16.split(String regex)returns a split string matching regex.
17.split(String regex, int limit)returns a split string matching regex and limit.
18.string intern()returns an interned string.
19.int indexOf(int ch)returns the specified char value index.
20.int indexOf(int ch, int fromIndex)returns the specified char value index starting with given index.
21.int indexOf(String substring)returns the specified substring index.
22.int indexOf(String substring, int fromIndex)returns the specified substring index starting with given index.
23.String toLowerCase()returns a string in lowercase.
24.String toLowerCase(Locale l)returns a string in lowercase using specified locale.
25.String toUpperCase()returns a string in uppercase.
26.String toUpperCase(Locale l)returns a string in uppercase using specified locale.
27.ing trim()removes beginning and ending spaces of this string.
28.static String valueOf(int value)converts given type into string. It is an overloaded method.

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