How to handle StringIndexOutOfBoundsException in Java?

Strings are used to store a sequence of characters in Java, they are treated as objects. The String class of the java.lang package represents a String.

You can create a String either by using the new keyword (like any other object) or, by assigning value to the literal (like any other primitive datatype).

Example

public class StringDemo {
   public static void main(String args[]) {
      String stringObject = new String("Hello how are you");
      System.out.println(stringObject);
      String stringLiteral = "Welcome to Tutorialspoint";
      System.out.println(stringLiteral);
   }
}

Output

Hello how are you
Welcome to Tutorialspoint

Index in an array

An array is a data structure/container/object that stores a fixed-size sequential collection of elements of the same type. The size/length of the array is determined at the time of creation.

The position of the elements in the array is called as index or subscript. The first element of the array is stored at the index 0 and, the second element is at the index 1 and so on.

Index in a Sting

Since the string stores an array of characters, just like arrays the position of each character is represented by an index (starting from 0). For example, if we have created a String as −

String str = "Hello";

The characters in it are positioned as −

StringIndexOutOfBoundsException

If you try to access the character of a String at the index which is greater than its length a StringIndexOutOfBoundsException is thrown.

Example

The String class in Java provides various methods to manipulate Strings. You can find the character at a particular index using the charAt() method of this class.

This method accepts an integer value specifying the index of theStringand returns the character in the String at the specified index.

In the following Java program, we are creating a String of length 17 and trying to print the element at the index 40.

public class Test {
   public static void main(String[] args) {
      String str = "Hello how are you";
      System.out.println("Length of the String: "+str.length());
      for(int i=0; i<str.length(); i++) {
         System.out.println(str.charAt(i));
      }
      //Accessing element at greater than the length of the String
      System.out.println(str.charAt(40));
   }
}

Run time exception

Since we are accessing the element at the index greater than its length StringIndexOutOfBoundsException is thrown.

Length of the String: 17
H
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Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 40
   at java.base/java.lang.StringLatin1.charAt(Unknown Source)
   at java.base/java.lang.String.charAt(Unknown Source)
   at Test.main(Test.java:9)

Handling StringIndexOutOfBoundsException exception

Just like other exceptions you can handle this exception by wrapping the code that is prone to it within try catch. In the catch block catch the exception of type IndexOutOfBoundsException or, StringIndexOutOfBoundsException.

public class Test {
   public static void main(String[] args) {
      String str = "Hello how are you";
      for(int i=0; i<tr.length(); i++) {
         System.out.println(str.charAt(i));
      }
      System.out.println(str.length());
      //Accessing element at greater than the length of the String
      try {
         System.out.println(str.charAt(40));
      }catch(StringIndexOutOfBoundsException e) {
         System.out.println("Exception occurred . . . . . . . . ");
      }
   }
}

Output

H
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17
Exception occurred . . . . . . . .