متد indexOf()‎ در جاوا

// Java String indexOf() 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.indexOf('J');
    System.out.println(result); // 6

    // the first occurrence of 'a' is returned
    result = str1.indexOf('a');
    System.out.println(result); // 2

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

    // getting the index of "ava"
    result = str1.indexOf("ava");

    System.out.println(result); // 7

    // substring not in the string
    result = str1.indexOf("java");

    System.out.println(result); // -1

    // index of empty string in the string
    result = str1.indexOf("");

    System.out.println(result); // 0
  }
}

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

    // getting the index of character 'a'
    // search starts at index 4
    result = str1.indexOf('a', 4);

    System.out.println(result);  // 7

    // getting the index of "Java"
    // search starts at index 8
    result = str1.indexOf("Java", 8);

    System.out.println(result);  // -1
  }
}