Find and Replace String In Java

Question

I have a String as follows

String str=" Hello World, Hello World, Hello";

I want to replace third "Hello" to "Hi" In Java. Is there any way that I can touch only the part I need in a String ?

Under what conditions do you want to change the "Hello" to "Hi"? Is it always the third "Hello"? Is it always the last "Hello"? — Craig, May 23 '13 at 02:00
Use `indexOf` three times to find the third "Hello", and then `substring` to build the updated String. — Thilo, May 23 '13 at 02:00
Also, look into `Pattern` and `Matcher` classes for regex matching and replacing. — Shadow Man, May 23 '13 at 02:04
POSSIBLE DUPLICATE OF http://stackoverflow.com/questions/13092406/java-replace-substring-in-string-specific-index — sunleo, May 23 '13 at 02:05

score 1 · Answer 1 · answered May 23 '13 at 02:04

1

Your logic is not totally explicit, but anyway I think the best is to use Pattern. Take a look at this tutorial.

answered May 23 '13 at 02:04

LexLythius

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jahroy · Answer 2 · 2013-05-23T05:26:54.397

Here's a method that will return the index of the nth occurrence of a string in another string:

/**
 *  Returns the index of the nth occurrence of needle in haystack.
 *  Returns -1 if less than n occurrences of needle occur in haystack.
 */
public int findOccurrence(String haystack, String needle, int n) {
    if (n < 1) {
        throw new IllegalArgumentException("silly rabbit...");
    }
    int count = 0;
    int len = needle.length();    
    int idx = haystack.indexOf(needle);
    while (idx != -1 && ++count < n) {
        idx = haystack.indexOf(needle, idx + len);
    }
    return idx;
}

The rest should be trivial to implement....

Find and Replace String In Java

2 Answers2