find the index of the first occurrence in a string java

String myStr = "Hello planet earth, you are a great planet."; System.out.println(myStr.indexOf("planet")); ... The indexOf() method returns the position of the first occurrence of specified character(s) in a string.

Medium

medium.com › @Neelesh-Janga › q-28-leetcode-find-the-index-of-the-first-occurrence-in-a-string-using-java-c56628b2d33c

Q-28 LeetCode: Find the Index of the First Occurrence in a String using Java

December 9, 2023 - Examples: 1. Input: haystack = "sadbutsad", needle = "sad" Output: 0 Explanation: "sad" occurs at index 0 and 6. The first occurrence is at index 0, so we return 0. 2. Input: haystack = "leetcode", needle = "leeto" Output: -1 Explanation: "leeto" ...

LeetCode

leetcode.com › problems › find-the-index-of-the-first-occurrence-in-a-string

Find the Index of the First Occurrence in a String - LeetCode

Find the Index of the First Occurrence in a String - Given two strings needle and haystack, return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

Stack Overflow

stackoverflow.com › questions › 46881080 › how-to-find-the-index-of-first-occurence-of-any-character-from-another-string-in

java - How to find the index of first occurence of any character from another string in a string? - Stack Overflow

You can use String.indexOf method which is present under string class.

AlgoMonster

algo.monster › liteproblems › 28

28. Find the Index of the First Occurrence in a String - In-Depth Explanation

In-depth solution and explanation for LeetCode 28. Find the Index of the First Occurrence in a String in Python, Java, C++ and more. Intuitions, example walk through, and complexity analysis. Better than official and forum solutions.

GitHub

github.com › doocs › leetcode › blob › main › solution › 0000-0099 › 0028.Find the Index of the First Occurrence in a String › README_EN.md

leetcode/solution/0000-0099/0028.Find the Index of the First Occurrence in a String/README_EN.md at main · doocs/leetcode

Input: haystack = "sadbutsad", needle = "sad" Output: 0 Explanation: "sad" occurs at index 0 and 6. The first occurrence is at index 0, so we return 0. ... Input: haystack = "leetcode", needle = "leeto" Output: -1 Explanation: "leeto" did not ...

Author doocs

GeeksforGeeks

geeksforgeeks.org › java › java-string-indexof

Java String indexOf() Method - GeeksforGeeks

November 19, 2024 - ... // Java code to demonstrate the working of String indexOf(char ch, int strt) public class Index2 { public static void main(String args[]) { String s = new String("Welcome to geeksforgeeks"); System.out.print( "Found g after 13th index at ...

TutorialKart

tutorialkart.com › java › get-the-index-of-first-occurrence-of-a-substring-in-a-string-using-java

How to get the index of first occurrence of a substring in a String using Java ?

May 4, 2023 - In this Java tutorial, you will learn how to find the index of first occurrence of a search string in a given string using String.indexOf() function, with examples.

Stack Overflow

stackoverflow.com › questions › 47089629 › find-the-first-occurence-of-a-character-in-a-string-java

Find the first occurence of a character in a string (java) - Stack Overflow

Top answer

1 of 1

Just return i for index of character in string as :

public static int findInStr(String s1, char c){
for (int i = 0; i < s1.length(); i++) {
    if (s1.charAt(i) == c) 
        return i;
}
return -1;

}

You can also use this method without using for loop::

public static int findInStr(String s1, char c){
    return s1.indexOf(c);

}

If character is not present in string indexOf return -1 otherwise index of first occurrence of character

WalkCCC

walkccc.me › LeetCode › problems › 28

28. Find the Index of the First Occurrence in a String - LeetCode Solutions

LeetCode Solutions in C++23, Java, Python, MySQL, and TypeScript.

Find elsewhere

Google Bing Mojeek

Medium

medium.com › @AlexanderObregon › solving-the-find-the-index-of-the-first-occurrence-in-a-string-problem-on-leetcode-a-java-a75bd406c1fc

Solving the ‘Find the Index of the First Occurrence in a String’ on LeetCode: Java Solutions…

February 1, 2024 - The KMP Algorithm is the most efficient approach for finding the index of the first occurrence of a substring in a string, due to its optimal time complexity, although it uses a bit more space compared to other methods.

Substack

alexanderobregon.substack.com › p › leetcode-28-find-the-index-of-the

LeetCode #28: Find the Index of the First Occurrence in a String — Solved in Java

October 24, 2025 - Thinking through a solution in Java starts with how string comparison works at the character level. Every character can be read directly with charAt, which lets you match needle against slices of haystack without creating new strings. The simplest way is to slide one index through the text and check for a match at every position, which helps build an understanding of how pattern matching works mechanically.

Stack Overflow

stackoverflow.com › questions › 15092941 › how-to-find-all-first-indexes-in-the-string

java - how to find all first indexes in the string? - Stack Overflow

Top answer

1 of 4

After you've found the first index, use the overloaded version of indexOf that receives the start index as a second parameter:

public int indexOf(int ch, int fromIndex) Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index.

Keep doing that until indexOf returns -1, indicating that there are no more matches to be found.

2 of 4

You can use regex with Pattern and Matcher. Matcher.find() tries to find the next match and Matcher.start() will give you the start index of the match.

Pattern p = Pattern.compile("create");
Matcher m = p.matcher("I would like to create a book reader  have create, create ");

while(m.find()) {
    System.out.println(m.start());
}

Baeldung

baeldung.com › home › java › java string › java string.indexof()

Java.String.indexOf() | Baeldung

April 11, 2025 - • Java String.indexOf() (current article)• Java String.intern() • Java String.isEmpty() • Java String.lastIndexOf() • Java String.regionMatches() • Java String.replace() • Java String.replaceAll() • Java String.split() • Java String.startsWith() • Java String.subSequence() • Java String.substring() • Java String.toLowerCase() • Java String.toUpperCase() • Java String.trim() • Java String.valueOf() The method indexOf() ...

GitHub

github.com › LeetCode-Feedback › LeetCode-Feedback › issues › 24614

Missing Test Case - 28. Find the Index of the First Occurrence in a String · Issue #24614 · LeetCode-Feedback/LeetCode-Feedback

October 5, 2024 - Find the Index of the First Occurrence in a String#24614 ... take input of sub-string here depicted as "needle" take input of super-string here depicted as "haystack" check index of sub-string the super_string use indexOf function ... import ...

Published Oct 05, 2024

NamasteDev

namastedev.com › home › mathematical foundations › algorithms and data structures › find index of first occurrence in string

Find Index of First Occurrence in String - NamasteDev Blogs

July 16, 2025 - int strStr(string haystack, string needle) { int n = haystack.length(); int m = needle.length(); for(int i = 0; i <= n - m; i++) { int j = 0; for(j = 0; j < m; j++) { if(haystack[i + j] != needle[j]) { break; } } if(j == m) { return i; } } return -1; }

TutorialsPoint

tutorialspoint.com › get-the-index-of-the-first-occurrence-of-a-separator-in-java

Get the index of the first occurrence of a separator in Java

public class Demo { public static ...Separator's first occurrence: "+sepPos); } } String: Tom-Hank-s Separator's first occurrence: 3 ... PHP – iconv_strpos() function – Find the position of the first occurrence of a needle in a haystack...

Sololearn

sololearn.com › en › Discuss › 1765293 › return-theindexposition-of-the-first-occurrence-ofein-the-following-string

Return the index (position) of the first occurrence of "e" in the following string: | Sololearn: Learn to code for FREE!

String txt = "Hello Everybody"; System.out.println(txt._______(___)); javamethodsstringindex · 19th Apr 2019, 7:19 AM · Hershewajue · 2 Answers · Answer · + 2 · Thanks. I later got the code to be System.out.println(txt.indexOf("e")); 19th Apr 2019, 7:45 AM ·

Medium

medium.com › @rutujakbhombe19 › leetcode-28-find-the-index-of-the-first-occurrence-in-a-string-03f36240f6bd

Leetcode 28: Find the Index of the First Occurrence in a String | by Rutuja Bhombe | Medium

August 11, 2024 - Input: haystack = "sadbutsad", needle = "sad" Output: 0 Explanation: "sad" occurs at index 0 and 6. The first occurrence is at index 0, so we return 0. ... Input: haystack = "leetcode", needle = "leeto" Output: -1 Explanation: "leeto" did not ...

w3resource

w3resource.com › java-exercises › basic › java-basic-exercise-118.php

Java - Get the first occurrence of a string within a string

Java programming exercises and solution: Write a Java program to get the first occurrence (Position starts from 0.) of a string within a given string.