Java – deletes the last line from StringBuilder without knowing the number of characters

I wonder if there is a simple way to delete the last line from the StringBuilder object without knowing the number of characters in the last line

Example:

I want to delete "OK, perfect..."

Solution

StringBuilder sb = new StringBuilder("Hello,how are you?\nFine thanks!\nOk,Perfect...");

StringBuilder sb = new StringBuilder("Hello,how are you?\nFine thanks!\nOk,Perfect...");

int last = sb.lastIndexOf("\n");
if (last >= 0) { sb.delete(last,sb.length()); }

http://ideone.com/9k8Tcj

Editor: if you want to delete the last non empty line

StringBuilder sb = new StringBuilder(
        "Hello,Perfect...\n\n");
if (sb.length() > 0) {
    int last,prev = sb.length() - 1;
    while ((last = sb.lastIndexOf("\n",prev)) == prev) { prev = last - 1; }
    if (last >= 0) { sb.delete(last,sb.length()); }
}

http://ideone.com/AlzQe0