FileHandler constructor NullPointerException - if pattern property is an empty String, but if count > 1
exception won't be thrown.

Example Main.java:

import java.util.logging.FileHandler;

public class Main {

    public static void main(String[] args) {
        FileHandler fh = null;
        try {
            fh = new FileHandler();
            System.out.println("fail");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (fh != null) {
                fh.close();
            }
        }
    }
}

property file: pr.properties:
java.util.logging.FileHandler.count = 2
java.util.logging.FileHandler.pattern=

Run:
jdk1.7.0_45b09\bin\java.exe -Djava.util.logging.config.file=pr.properties Main
fail

file with name .0 will be created in the current folder

If we change pr.properties:
java.util.logging.FileHandler.count = 1
java.util.logging.FileHandler.pattern=

and run again:
jdk1.7.0_45b09\bin\java.exe -Djava.util.logging.config.file=pr.properties Main
java.lang.NullPointerException
        at java.util.logging.FileHandler.openFiles(FileHandler.java:392)
        at java.util.logging.FileHandler.<init>(FileHandler.java:225)
        at Main.main(Main.java:8)

NPE was thrown as expected.