Java String charAt()

The Java String class charAt() method returns a char value at the given index number .

The index number starts from 0 and goes to n-1, where n is the length of the string. It returns StringIndexOutOfBoundsException, if the given index number is greater than or equal to this string length or a negative number.

Syntax

public char charAt(int index)

The method accepts index as a parameter. The starting index is 0. It returns a character at a specific index position in a string. It throws StringIndexOutOfBoundsException if the index is a negative value or greater than this string length.

Specified by

CharSequence interface, located inside java.lang package.

Internal implementation

public char charAt(int index) { if ((index < 0) || (index >= value.length)) { throw new StringIndexOutOfBoundsException(index); return value[index];

Java String charAt() Method Examples

Let's see Java program related to string in which we will use charAt() method that perform some operation on the give string.

FileName: CharAtExample.java

public class CharAtExample{ public static void main(String args[]){ String name="javatpoint"; char ch=name.charAt(4);//returns the char value at the 4th index System.out.println(ch); Test it Now

Output:

Let's see the example of the charAt() method where we are passing a greater index value. In such a case, it throws StringIndexOutOfBoundsException at run time.

FileName: CharAtExample.java

public class CharAtExample{ public static void main(String args[]){ String name="javatpoint"; char ch=name.charAt(10);//returns the char value at the 10th index System.out.println(ch);

Output:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 10 at java.lang.String.charAt(String.java:658) at CharAtExample.main(CharAtExample.java:4)

Accessing First and Last Character by Using the charAt() Method

Let's see a simple example where we are accessing first and last character from the provided string.

FileName: CharAtExample3.java

public class CharAtExample3 { public static void main(String[] args) { String str = "Welcome to Javatpoint portal"; int strLength = str.length(); // Fetching first character System.out.println("Character at 0 index is: "+ str.charAt(0)); // The last Character is present at the string length-1 index System.out.println("Character at last index is: "+ str.charAt(strLength-1));

Output:

Character at 0 index is: W Character at last index is: l

Print Characters Presented at Odd Positions by Using the charAt() Method

Let's see an example where we are accessing all the elements present at odd index.

FileName: CharAtExample4.java

public class CharAtExample4 { public static void main(String[] args) { String str = "Welcome to Javatpoint portal"; for (int i=0; i<=str.length()-1; i++) { if(i%2!=0) { System.out.println("Char at "+i+" place "+str.charAt(i));

Output:

Char at 1 place e Char at 3 place c Char at 5 place m Char at 7 place Char at 9 place o Char at 11 place J Char at 13 place v Char at 15 place t Char at 17 place o Char at 19 place n Char at 21 place Char at 23 place o Char at 25 place t Char at 27 place l

The position such as 7 and 21 denotes the space.

Counting Frequency of a character in a String by Using the charAt() Method

Let's see an example in which we are counting frequency of a character in the given string.

FileName: CharAtExample5.java

public class CharAtExample5 { public static void main(String[] args) { String str = "Welcome to Javatpoint portal"; int count = 0; for (int i=0; i<=str.length()-1; i++) { if(str.charAt(i) == 't') { count++; System.out.println("Frequency of t is: "+count);

Output:

Frequency of t is: 4

Counting the Number of Vowels in a String by Using the chatAt() Method

Let's see an example where we are counting the number of vowels present in a string with the help of the charAt() method.

FileName: CharAtExample6.java

// import statement import java.util.*; public class CharAtExample6 ArrayList al; // constructor for creating and // assigning values to the ArrayList al CharAtExample6() al = new ArrayList (); al.add('A'); al.add('E'); al.add('a'); al.add('e'); al.add('I'); al.add('O'); al.add('i'); al.add('o'); al.add('U'); al.add('u'); // a method that checks whether the character c is a vowel or not private boolean isVowel(char c) for(int i = 0; i < al.size(); i++) if(c == al.get(i)) return true; return false; // a method that calculates vowels in the String s public int countVowels(String s) int countVowel = 0; // store total number of vowels int size = s.length(); // size of string for(int j = 0; j < size; j++) char c = s.charAt(j); if(isVowel(c)) // vowel found! // increase the count by 1 countVowel = countVowel + 1; return countVowel; // main method public static void main(String argvs[]) // creating an object of the class CharAtExample6 CharAtExample6 obj = new CharAtExample6(); String str = "Javatpoint is a great site for learning Java."; int noOfVowel = obj.countVowels(str); System.out.println("String: " + str); System.out.println("Total number of vowels in the string are: "+ noOfVowel + "\n"); str = "One apple in a day keeps doctor away."; System.out.println("String: " + str); noOfVowel = obj.countVowels(str); System.out.println("Total number of vowels in the string are: "+ noOfVowel);

Output:

String: Javatpoint is a great site for learning Java. Total number of vowels in the string are: 16 String: One apple in a day keeps doctor away. Total number of vowels in the string are: 13 Next Topic Java String compareTo ← prev next →