In java there are lot of string methods that allow us to perform operation on a string or we can say sequence of char values.For example indexOf(int),it returns the index of first occurance of specified character in the string.

So we will discuss strings methods which are performed on strings.

Length()

As the name suggest from length,means it is used to calculate the length of string,return type of this function is integer

We will understand this in program.

IndexOf(String)

As the name suggest index,means it will return index value of first character of the substring from the string, which is given to function as a parameter.If the character is not present in the string it will return -1

Example:

charAt(int)

In this function we pass index value as a parameter and it will return the character at the given index.Here the index value start from 0 and it will goes to n-1,where n is the length of string.The starting index will be from 0.

Example:

replace(String,String)

This function takes two strings or characters as a parameters,and it will replace the old string with a new string.
Here the first parameter tells the old string or character which should be replaced, and second parameter tells by which string or character it should be replaced.

toLowerCase()

This function converts all the characters in a string in a lowercase.

Example:

toUpperCase()

This function converts all the characters in a string in a lowercase,and then returns the converted string.

Example:

compareTo()

This function is basically used to compare two strings.It works on the the basis of unicode of each chaeracter in a string

This function returns on the basis of following conditions:-

1. It returns 0,if two strings are equal.
2. It returns positive(+),if firstmismatch character of first string is greater than firstmismatch character of second String
3. It returns negative(-),if firstmismatch character of first string is lesser than firstmismatch character of second String

Example:

In the above example, we can observe that:-

1. when String hello is compared to String "hello" , it will result zero,because these String are equal
   hello.compareTo("hello")
2. When String "hello" is compared to String "Hello", it will result to positive value 32,as here we are taking difference of unicode(h) and unicode(H) which will output to positive value 32.
   
   
3. When String "hello" is compared to String "world", it will result to negative value -15,as here we are taking difference of unicode(h) and unicode(w) which will output to negative value .
   
   

trim()

This function is used to remove all the white space from after and before the string.It will output to the copy of original string,without after and before whitespace.

equals(String str)

This function is basically used for comparision,it will compare two string and return true,if both strings are equal,and return false,if both strings are not equal.

Example:-

equalsIgnoreCase(String str)

This function works similar to equals() function,it check whether two strings are equal or not,and return false if they are not equal and true if both strings are equal. The only major difference between these two functions is equalsIgnoreCase() does not check the case sensitivity,i.e uppercase and lowercase.That is it will return true if one string is in uppercase and other string is in lowercase.

Example:-

In the above example,we can observe:-

1. When string "java tutorials" is compared to "tutorials",it will return false as both strings are not equal
2. When string "java tutorials" is compared to "JAVA TUTORIALS",it will return true,because case sensitivity is ignored here.