Java String charAt() Method examples (Find Char At a Given Index)

1. Introduction

In this article, We'll learn how to find the character at an index with String charAt in java.

The Java String charAt(int index) method returns the character at the specified index in a string. The index value should be between 0 and (length of string-1). For example, s.charAt(0) would return the first character of the string represented by instance s. Java String charAt method throws IndexOutOfBoundsException if the index value passed in the charAt() method is a negative number or less than zero or greater than or equal to the length of the string (index<0|| index>=length()). IndexOutOfBoundsException means index if out of its range and it occurs at runtime.

Java String charAt() Examples 

Syntax:

public char charAt​(int index)

We will show the example programs on the following use cases. 

1: Finding first, mid and last index of the given string.
2: IndexOutOfBoundsException when using charAt() method.
3: Printing String char by char using charAt() method.
4: Printing even numbers of index characters.
5: Printing odd number index characters
6: Counting number of occurrences of a character

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2. Java String charAt() Method examples:

Example 1: Finding first, mid and last index of the given string.

how to use charat in java

package examples.java.w3schools.string;

public class StringCharAtExample {
 public static void main(String[] args) {

   String input = "michael jackson";

  // first character
  char ch1 = input.charAt(0);

  // third character
  char ch3 = input.charAt(2);

   // tenth character
  char ch10 = input.charAt(9);
  
  System.out.println("Character at 0 index is "+ch1);
  System.out.println("Character at 2 index is "+ch3);
  System.out.println("Character at 9 index is "+ch10);
 }
}

Output:

Character at 0 index is m
Character at 2 index is c
Character at 9 index is a

3. Example 2: IndexOutOfBoundsException when using charAt() method

If the index is not in the range of 0 to length-1 then will through IndexOutOfBoundsException.

Output:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 15

at java.lang.String.charAt(Unknown Source)

at examples.java.w3schools.string.StringCharAtExample.main(StringCharAtExample.java:7)

4. Example 3: Printing String char by char using charAt() method

package examples.java.w3schools.string;

public class StringCharAtExample {
 public static void main(String[] args) {

   String input = "iterate";
  for(int i=0; i< input.length();i++){
   System.out.println(input.charAt(i));
  }
 }
}

Output:

i
t
e
r
a
t
e

5. Example 4: Printing even number index characters

package examples.java.w3schools.string;
public class StringCharAtExample {
 public static void main(String[] args) {
   String input = "123456789";
  for(int i=0;i< input.length();i=i+2){
   System.out.println("Index "+i+" : "+input.charAt(i));
  }
 }
}

Output:

Index 0 : 1
Index 2 : 3
Index 4 : 5
Index 6 : 7
Index 8 : 9

6. Example 5: Printing an odd number of index characters

package examples.java.w3schools.string;

public class StringCharAtExample {
 public static void main(String[] args) {

   String input = "123456789";
  for(int i=1;i< input.length();i=i+2){
   System.out.println("Index "+i+" : "+input.charAt(i));
  }
 }
}

Output:

Index 1 : 2
Index 3 : 4
Index 5 : 6
Index 7 : 8

7. Example 6: Counting number of occurrences of a character

public class StringCharAtExample {
 public static void main(String[] args) {
  int count = 0;
  String input = "abbbccbbbc";
  for (int i = 0; i < input.length(); i++) {
   if (input.charAt(i) == 'b') {
    count++;
   }
  }
  System.out.println("No. of occurrences of b character is : " + count);
 }
}

Now we will find how many times character b is present in the string.

Output:

No. of occurrences of b character is: 6

Please post your questions in the comments section.

8. Conclusion

In this tutorial, We've seen when to use charAt() method in java and example programs to get even or odd indexed values.


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