Java.lang.StringBuilder.indexOf() Method

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Description

The java.lang.StringBuilder.indexOf(String str, int fromIndex) method returns the index within this string of the first occurrence of the specified substring, starting at the specified index.

Declaration

Following is the declaration for java.lang.StringBuilder.indexOf() method

public int indexOf(String str, int fromIndex)

Parameters

• str − This is the substring for which to search.

• fromIndex − This is the index from which to start the search.

Return Value

This method returns the index within this string of the first occurrence of the specified substring, starting at the specified index.

Exception

NullPointerException − if str is null.

Example

The following example shows the usage of java.lang.StringBuilder.indexOf() method.

package com.tutorialspoint;

import java.lang.*;

public class StringBuilderDemo {

   public static void main(String[] args) {
  
      StringBuilder str = new StringBuilder("programming language");
      System.out.println("string = " + str);
  
      // returns the index of the specified substring
      System.out.println("Index of substring = " + str.indexOf("age"));
  
      /* returns the index of the specified substring, starting at 
         the specified index */
      System.out.println("Index of substring = " + str.indexOf("am",2));
  
      /* returns -1 as the substring is not found starting at the
         specified index */
      System.out.println("Index of substring = " + str.indexOf("am",10)); 
   }
}  

Let us compile and run the above program, this will produce the following result −

string = programming language
Index of substring = 17
Index of substring = 5
Index of substring = -1