🎯 10 most useful string methods in Java 
Tags: java, programming, computerscience
Published: 2022-01-19 17:55:20

**Introduction on Strings**
String is an object that represents sequence of char values. Strings are immutable in Java.There are two ways to create string in Java
1 - By String literal
2 - By new keyword
![Method to create strings in java](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/jnhtqlt9diwdjzsoy9f2.png)
📌 Note: String literal create no new object if it exists already in the string constant pool (SCP) which is a special place for all strings in heap memory. Create string of same object using new keyword.This will create new object outside the string pool if it already exist in it 

_**1 - indexOf()**_ used to find characters and substrings in a string. It returns the index of first occurrence from left of the passed string or character
syntax - public int indexOf​(String str, int fromIndex)
str - substring to be search
fromIndex - search begin from this index

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/0mlymwr4yvhctei85dlm.png)
**_2 - toCharArray()_** used to form a character array of a string
syntax - public char[] toCharArray()

▶️Example : check if string is palindrome of not

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/q8y0pfbohgg4p164kf3c.png)
3 - charAt() Used to find the character at particular index
syntax - public char charAt​(int index)

▶️ Example : count no. of spaces in the string

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/0bfi1iqqyzuxya9n7u8a.png)
**_4 - concat()_** Used to concatenate two strings
syntax - public String concat(String str)

▶️ Example : concatenate last name and firstname

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/j66h9pvbfxjy1fi2winb.png)
**_5 - replace()_** Used for replacing characters and substrings in a string
syntax - public String replace​(char oldChar, char newChar)

▶️ Example : remove all white spaces from the string

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/m0gvz9i10lwst3gs4qyq.png)
**_6 - substring()_** Used to extract a portion of a string from original string
syntax - public String substring​(int beginIndex, int endIndex)

▶️Example : print first 3 character of a string

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/0demkdneym2sdylozj73.png)
**_7 - split()_** Used to breaks a given string around matches of the given regular expression.After splitting against the given regular expression, this method returns a char array
syntax - public String[] split​(String regex, int limit)
limit : number of strings return after split

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/qh2zu28ks5pt2w0ttew8.png)
**_8 - compareTo()_** It compares the given string with the current string lexicographically. It returns a positive number, negative number, or 0
if s1 > s2, returns +ve number
if s1 < s2, returns -ve number
if s1 == s2, returns 0
syntax : public int compareTo(String anotherString)

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/1dcj5mldefzuea7uq2qa.png)
**_9 - strip()_** To eliminate all trailing and leading whitespaces from the given string
syntax - public String strip()
▶️ Example
![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/tduzzzth1gbi0nttv2ym.png)
**_10 - valueOf()_** Used to return string representation of passed argument
syntax - public static String valueOf​(char[] data)
Note : valueOf() has many overloaded variants that aid in the conversion of almost any primitive form to string

![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/ajrpyixwnzmspcsemos9.png)