### Implement strStr() or indexOf() Java Solution - The Coding Shala

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## Implement strStr() or indexOf() Java Solution

Problem:

Return the index of the first occurrence of needle in the haystack, or -1 if the needle is not part of haystack.

Example 1:

Input: haystack = "hello", needle = "ll"
Output: 2

Example 2:

Input: haystack = "aaaaa", needle = "bba"
Output: -1

### Implement strStr() or indexOf() Java Solution

Approach:
If the needle char does not match with haystack return -1 else continue checking.

Java

```class Solution {
public int strStr(String haystack, String needle) {
int len1 = haystack.length();
int len2 = needle.length();
if(len2 == 0) return 0;
int index = -1;
if(len2>len1) return -1;
for(int i=0; i<len1; i++){
int flag=0;
if(haystack.charAt(i) == needle.charAt(0)){
int tmp = i;
int cnt = 0;
while(tmp < len1 && cnt<len2){
if(haystack.charAt(tmp)!=needle.charAt(cnt)){
flag=1;
break;
}
cnt++;
tmp++;
}
if(flag==0 && cnt==len2) { index = i; break;}
}
}
return index;
}
}
```

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