How do I make string.indexof() stop at the end string.length() in a for loop in java

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Java

Hello everyone, I am using String.indexOf() to find all occurrences of a character in a string using a for loop. The problem is, I taught that if I iterate over the string in a for loop till the end of the length of the string the iteration should end and print only the occurrences of that character that was found but the for loop still prints -1, meaning that it didn't stop after finding the last occurrence of the character.

What I have tried:

public static void main(String[] args) {

     String str1 = "hello from lagos";
	   String guess = "l";
	   int index = str1.indexOf(guess);
	   System.out.println("index is : " + index); // to show where the first occurrence is 
	   for(int i = 0; i < str1.length(); i++) {
		   System.out.println("For many ocuurrences: " + index);
		   index = str1.indexOf(guess, index + 1);
		      
	   }
	}

Output:

index is : 2
For many ocuurrences: 2
For many ocuurrences: 3
For many ocuurrences: 11
For many ocuurrences: -1
For many ocuurrences: 2
For many ocuurrences: 3
For many ocuurrences: 11
For many ocuurrences: -1
For many ocuurrences: 2
For many ocuurrences: 3
For many ocuurrences: 11
For many ocuurrences: -1
For many ocuurrences: 2
For many ocuurrences: 3
For many ocuurrences: 11
For many ocuurrences: -1

My question is: why didn't the loop stop after printing the first 2, 3 and 11. Why is it printing -1 and why didn't the loop stop after the printing the first 11 ? Thanks for any help.