问如何在不使用Java中的replace函数的情况下替换字符串中的字符？

EN

else if (UserCommand.equalsIgnoreCase("replace first"))
    {
        System.out.println("Enter the character to replace");
        String Replace = input.next();
        System.out.println("Enter the new character");
        String Replacement = input.next();
        for (int i = 0; i<String.length();i++)
        {
            if (String.charAt(i)==Replace.charAt(0)) 
            {
                StringEdit = String.substring(0,i) + Replacement + String.substring(i + Replace.length());
            }
        }