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Pankaj Singh
Pankaj Singh

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🎯 10 most useful string methods in Java

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
📌 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

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2 - toCharArray() used to form a character array of a string
syntax - public char[] toCharArray()

▶️Example : check if string is palindrome of not

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3 - charAt() Used to find the character at particular index
syntax - public char charAt​(int index)

▶️ Example : count no. of spaces in the string

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4 - concat() Used to concatenate two strings
syntax - public String concat(String str)

▶️ Example : concatenate last name and firstname

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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

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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

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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

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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)

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9 - strip() To eliminate all trailing and leading whitespaces from the given string
syntax - public String strip()
▶️ Example
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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

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