I am trying to create a JavaFX program, and every time I try to run my code I am getting an exception – I’m not entirely sure what it means though… My code: Stack trace: Any help will be appreciated, Thanks Ask Question
Here is a real life sample. Note that String also implements Comparable. later..
They are entirely different constructs. A HashMap is an implementation of Map. A Map maps keys to values. The key look up occurs using the hash. On the other hand, a HashSet is an implementation of Set. A Set is designed to match the mathematical model of a set. A HashSet does use a HashMap to back its implementation, as you noted. However, it implements an entirely different interface. … Read more
To reverse an int array, you swap items up until you reach the midpoint, like this: The way you are doing it, you swap each element twice, so the result is the same as the initial list.
It depends on what form of date / time you want: If you want the date / time as a single numeric value, then System.currentTimeMillis() gives you that, expressed as the number of milliseconds after the UNIX epoch (as a Java long). This value is a delta from a UTC time-point, and is independent of the local time-zone1. … Read more
“N/A” is not an integer. It must throw NumberFormatException if you try to parse it to an integer. Check before parsing or handle Exception properly. Exception Handlingtry{ int i = Integer.parseInt(input); } catch(NumberFormatException ex){ // handle your exception … } or – Integer pattern matching –
^ in java does not mean to raise to a power. It means XOR. You can use java’s Math.pow() And you might want to consider using double instead of int—that is: Note that 199/100 evaluates to 1.
% is the Modulus operator. For Java Modulus: For example: 10 % 3 is equal to 1. To visually see this – You can think of it as “How much would I have to subtract to the value on the left in order to make it evenly divisible by the right hand value?” And yes, actually it’s … Read more
is there a possibility that casting a double created via Math.round() will still result in a truncated down number No, round() will always round your double to the correct value, and then, it will be cast to an long which will truncate any decimal places. But after rounding, there will not be any fractional parts remaining. Here are the docs from Math.round(double): … Read more
You can use the List.addAll() method. It accepts a Collection as an argument, and your set is a Collection. EDIT: as respond to the edit of the question.It is easy to see that if you want to have a Map with Lists as values, in order to have k different values, you need to create k different lists.Thus: You cannot avoid … Read more