What is the indexOf() method of the String class?

The indexOf() method of the String class is used to search the first occurrence of a character or a substring from a given string. This method is overloaded in several ways. In all ways, the method either returns the index at which the character or substring was found, or returns -1 on failure.

To search for the first occurrence of a character, the following is used:

int indexOf(int ch)

here, ch specifies the character being searched.

To search for the first occurrence of a substring, the following is used:

int indexOf(String str)

here, str specifies the substring being searched.

To search the occurrence of a character from a starting index, the following is used:

int indexOf(int ch, int startIndex)

To search the occurrence of a substring from a starting index, the following is used:

int indexOf(String str, int startIndex)

here, startIndex specifies the point from which the search for a character or a substring begins. The search begins from the startIndex to the end of the string.

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