java.lang.IllegalArgumentException: Illegal Capacity: -1
at java.util.ArrayList.<init>(ArrayList.java:130)
at menu.SubsetSum$Combination.call(SubsetSum.java:144)
at menu.SubsetSum$Combination.call(SubsetSum.java:99)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)
Exception in thread "main" java.lang.NullPointerException
at menu.Menu.order(Menu.java:184)
at Main.main(Main.java:52)