Java String lastIndexOf()

The syntax of the String lastIndexOf() method either

string.lastIndexOf(int ch, int index)

or

string.lastIndexOf(string str, int index)

lastIndexOf() Parameters

To find the last index of a character, lastIndexOf() takes these two parameters:

• ch - the character whose last index is to be found
• index (optional) - if index is passed, the ch character is searched from start to this index

To find the last index of the specified substring within the string, lastIndexOf() takes these two parameters:

• str - the string whose last index is to be found
• index (optional) - if index is passed, the str string is searched from start to this index

lastIndexOf() Return Value

• returns the index of the last occurrence of the specified character/string
• returns -1 if the specified character/string is not found.

Example 1: Java String lastIndexOf()

// Java String lastIndexOf() with only one parameter
class Main {
  public static void main(String[] args) {
    String str1 = "Learn Java";
    int result;

    // getting index of character 'J'
    result = str1.lastIndexOf('J');
    System.out.println(result); // 6

    // the last occurrence of 'a' is returned
    result = str1.lastIndexOf('a');
    System.out.println(result); // 9

    // character not in the string
    result = str1.lastIndexOf('j');
    System.out.println(result); // -1

    // getting the last occurrence of "ava"
    result = str1.lastIndexOf("ava");
    System.out.println(result); // 7

    // substring not in the string
    result = str1.lastIndexOf("java");
    System.out.println(result); // -1
  }
}

Note: The character 'a' occurs multiple times in the "Learn Java" string. The lastIndexOf() method returns the index of the last occurrence of 'a' (which is 9).

Example 2: lastIndexOf() With fromIndex Parameter

class Main {
  public static void main(String[] args) {
    String str1 = "Learn Java programming";
    int result;

    // search from index 0 to 4
    // searches the substring "Learn"
    result = str1.lastIndexOf('r', 4);
    System.out.println(result); // 3

    // search from index 0 to 12
    // searcheses the substring "Learn Java pr"
    result = str1.lastIndexOf('r', 12);
    System.out.println(result); // 12

    // string length is less than 100
    // searches the whole string
    result = str1.lastIndexOf('r', 70);
    System.out.println(result); // 15

    // searches the substring "Learn"
    result = str1.lastIndexOf("Java", 4);
    System.out.println(result); // -1
  }
}

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