java-tutorials/java-strings/src/main/java/com/baeldung/string/ReplaceCharacterInString.java

package com.baeldung.string;

public class ReplaceCharacterInString {
    public  String replaceCharSubstring(String str, char ch, int index) {
        String myString = str.substring(0, index) + ch + str.substring(index+1);
        return myString;
    }

    public  String replaceCharStringBuilder(String str, char ch, int index) {
        StringBuilder myString = new StringBuilder(str);
        myString.setCharAt(index, ch);
        return myString.toString();
    }

    public String replaceCharStringBuffer(String str, char ch, int index) {
        StringBuffer myString = new StringBuffer(str);
        myString.setCharAt(index, ch);
        return myString.toString();
    }

}