Which of the methods are methods of the string class?

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How many methods are there in string class?
What are the string 5 methods?
Which of the method is not there in string class?
What are the methods of string object?

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String is a sequence of characters. In java, objects of String are immutable which means a constant and cannot be changed once created.

Creating a String

There are two ways to create string in Java:

String literal
```
String s = “GeeksforGeeks”;
```

Using new keyword

String s = new String (“GeeksforGeeks”);

Constructors

String(byte[] byte_arr) – Construct a new String by decoding the byte array. It uses the platform’s default character set for decoding.
Example:
```
byte[] b_arr = {71, 101, 101, 107, 115};
String s_byte =new String(b_arr); //Geeks
```
String(byte[] byte_arr, Charset char_set) – Construct a new String by decoding the byte array. It uses the char_set for decoding.
Example:
```
byte[] b_arr = {71, 101, 101, 107, 115};
Charset cs = Charset.defaultCharset();
String s_byte_char = new String(b_arr, cs); //Geeks
```
String(byte[] byte_arr, String char_set_name) – Construct a new String by decoding the byte array. It uses the char_set_name for decoding.
It looks similar to the above constructs and they appear before similar functions but it takes the String(which contains char_set_name) as parameter while the above constructor takes CharSet.
Example:
```
byte[] b_arr = {71, 101, 101, 107, 115};
String s = new String(b_arr, "US-ASCII"); //Geeks
```
String(byte[] byte_arr, int start_index, int length) – Construct a new string from the bytes array depending on the start_index(Starting location) and length(number of characters from starting location).
Example:
```
byte[] b_arr = {71, 101, 101, 107, 115};
String s = new String(b_arr, 1, 3); // eek
```
String(byte[] byte_arr, int start_index, int length, Charset char_set) – Construct a new string from the bytes array depending on the start_index(Starting location) and length(number of characters from starting location).Uses char_set for decoding.
Example:
```
byte[] b_arr = {71, 101, 101, 107, 115};
Charset cs = Charset.defaultCharset();
String s = new String(b_arr, 1, 3, cs); // eek
```
String(byte[] byte_arr, int start_index, int length, String char_set_name) – Construct a new string from the bytes array depending on the start_index(Starting location) and length(number of characters from starting location).Uses char_set_name for decoding.
Example:
```
byte[] b_arr = {71, 101, 101, 107, 115};
String s = new String(b_arr, 1, 4, "US-ASCII"); // eeks
```
String(char[] char_arr) – Allocates a new String from the given Character array
Example:
```
char char_arr[] = {'G', 'e', 'e', 'k', 's'};
String s = new String(char_arr); //Geeks
```
String(char[] char_array, int start_index, int count) – Allocates a String from a given character array but choose count characters from the start_index.
Example:
```
char char_arr[] = {'G', 'e', 'e', 'k', 's'};
String s = new String(char_arr , 1, 3); //eek
```
String(int[] uni_code_points, int offset, int count) – Allocates a String from a uni_code_array but choose count characters from the start_index.
Example:
```
int[] uni_code = {71, 101, 101, 107, 115};
String s = new String(uni_code, 1, 3); //eek
```

String(StringBuffer s_buffer) – Allocates a new string from the string in s_buffer
Example:

StringBuffer s_buffer = new StringBuffer("Geeks");
String s = new String(s_buffer); //Geeks

String(StringBuilder s_builder) – Allocates a new string from the string in s_builder
Example:

StringBuilder s_builder = new StringBuilder("Geeks");
String s = new String(s_builder); //Geeks

String Methods

int length(): Returns the number of characters in the String.
```
"GeeksforGeeks".length();  // returns 13
```
Char charAt(int i): Returns the character at ith index.
```
"GeeksforGeeks".charAt(3); // returns  ‘k’
```
String substring (int i): Return the substring from the ith index character to end.
```
"GeeksforGeeks".substring(3); // returns “ksforGeeks”
```
String substring (int i, int j): Returns the substring from i to j-1 index.
```
 "GeeksforGeeks".substring(2, 5); // returns “eks”
```

String concat( String str): Concatenates specified string to the end of this string.

 String s1 = ”Geeks”;
 String s2 = ”forGeeks”;
 String output = s1.concat(s2); // returns “GeeksforGeeks”

int indexOf (String s): Returns the index within the string of the first occurrence of the specified string.
```
 String s = ”Learn Share Learn”;
 int output = s.indexOf(“Share”); // returns 6
```
int indexOf (String s, int i): Returns the index within the string of the first occurrence of the specified string, starting at the specified index.
```
 String s = ”Learn Share Learn”;
 int output = s.indexOf("ea",3);// returns 13
```
Int lastIndexOf( String s): Returns the index within the string of the last occurrence of the specified string.
```
 String s = ”Learn Share Learn”;
 int output = s.lastIndexOf("a"); // returns 14
```

boolean equals( Object otherObj): Compares this string to the specified object.

 Boolean out = “Geeks”.equals(“Geeks”); // returns true
 Boolean out = “Geeks”.equals(“geeks”); // returns false

boolean equalsIgnoreCase (String anotherString): Compares string to another string, ignoring case considerations.

 Boolean out= “Geeks”.equalsIgnoreCase(“Geeks”); // returns true
 Boolean out = “Geeks”.equalsIgnoreCase(“geeks”); // returns true

int compareTo( String anotherString): Compares two string lexicographically.

 int out = s1.compareTo(s2);  // where s1 and s2 are
                             // strings to be compared

 This returns difference s1-s2. If :
 out < 0  // s1 comes before s2
 out = 0  // s1 and s2 are equal.
 out > 0   // s1 comes after s2.

int compareToIgnoreCase( String anotherString): Compares two string lexicographically, ignoring case considerations.

 int out = s1.compareToIgnoreCase(s2);  
// where s1 and s2 are 
// strings to be compared

 This returns difference s1-s2. If :
 out < 0  // s1 comes before s2
 out = 0   // s1 and s2 are equal.
 out > 0   // s1 comes after s2.

Note- In this case, it will not consider case of a letter (it will ignore whether it is uppercase or lowercase).

String toLowerCase(): Converts all the characters in the String to lower case.

String word1 = “HeLLo”;
String word3 = word1.toLowerCase(); // returns “hello"

String toUpperCase(): Converts all the characters in the String to upper case.

String word1 = “HeLLo”;
String word2 = word1.toUpperCase(); // returns “HELLO”

String trim(): Returns the copy of the String, by removing whitespaces at both ends. It does not affect whitespaces in the middle.
```
String word1 = “ Learn Share Learn “;
String word2 = word1.trim(); // returns “Learn Share Learn”
```
String replace (char oldChar, char newChar): Returns new string by replacing all occurrences of oldChar with newChar.
```
String s1 = “feeksforfeeks“;
String s2 = “feeksforfeeks”.replace(‘f’ ,’g’); // returns “geeksgorgeeks”
```
Note:- s1 is still feeksforfeeks and s2 is geeksgorgeeks

Program to illustrate all string methods:

import java.io.*;

import java.util.*;

class Test

{

public static void main (String[] args)

{

String s= "GeeksforGeeks";

System.out.println("String length = " + s.length());

System.out.println("Character at 3rd position = "

+ s.charAt(3));

System.out.println("Substring " + s.substring(3));

System.out.println("Substring = " + s.substring(2,5));

String s1 = "Geeks";

String s2 = "forGeeks";

System.out.println("Concatenated string = " +

s1.concat(s2));

String s4 = "Learn Share Learn";

System.out.println("Index of Share " +

s4.indexOf("Share"));

System.out.println("Index of a = " +

s4.indexOf('a',3));

Boolean out = "Geeks".equals("geeks");

System.out.println("Checking Equality " + out);

out = "Geeks".equals("Geeks");

System.out.println("Checking Equality " + out);

out = "Geeks".equalsIgnoreCase("gEeks ");

System.out.println("Checking Equality " + out);

int out1 = s1.compareTo(s2);

System.out.println("the difference between ASCII value is="+out1);

String word1 = "GeeKyMe";

System.out.println("Changing to lower Case " +

word1.toLowerCase());

String word2 = "GeekyME";

System.out.println("Changing to UPPER Case " +

word2.toUpperCase());

String word4 = " Learn Share Learn ";

System.out.println("Trim the word " + word4.trim());

String str1 = "feeksforfeeks";

System.out.println("Original String " + str1);

String str2 = "feeksforfeeks".replace('f' ,'g') ;

System.out.println("Replaced f with g -> " + str2);

}

Output :

String length = 13
Character at 3rd position = k
Substring ksforGeeks
Substring = eks
Concatenated string = GeeksforGeeks
Index of Share 6
Index of a = 8
Checking Equality false
Checking Equality true
Checking Equality false
the difference between ASCII value is=-31
Changing to lower Case geekyme
Changing to UPPER Case GEEKYME
Trim the word Learn Share Learn
Original String feeksforfeeks
Replaced f with g -> geeksgorgeeks

For Set – 2 you can refer: Java.lang.String class in Java | Set 2

This article is contributed by Rahul Agrawal. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above

How many methods are there in string class?

Strings are a sequence of characters and are widely used in Java programming. In the Java programming language, strings are objects. The String class has over 60 methods and 13 constructors.

What are the string 5 methods?

String Methods.

length() String Method in Java..

concat() String Method in Java..

String Method equals() in Java..

indexOf() String Method in Java..

charAt() String Method in Java..

toUpperCase() and toLowerCase() String Methods..

Which of the method is not there in string class?

Why there is no reverse method in String class in Java? Instead, the reverse() method is provided in StringBuilder ? Is there a reason for this? But String has split() , regionMatches() , etc., which are more complex than the reverse() method.