The easiest way is to, as @KrisRoofe suggested, read the json, then add an element. I would do this by converting the existing json in the file to a Map. Since you don’t actually care about the existing json, all you want to do is add a new entry to that Map. Once you do … Read more
The List<Pack> in your HashMaps are never defined. They are of the interface list but nowhere you identify what kind of List they are. You have to follow a structure as follows: Map<long, List<Pack>> map = new HashMap<>() // java 7 syntax List<Pack> packets = new ArrayList<>(); packets.add(pack); map.put(msg.getAck(), packets); When adding an element to … Read more
pop() is not working because you are using different objects for push and pop. You don’t need to define another class for push and pop, they are operation add those function inside Stack class. class Stack { … // members and constructor public void push(){..} public void pop(){..} public void show(){..} } And create an … Read more
If the first line in the method isn’t executed, then the method simply doesn’t get called. There is a chance, that it is actually executed and System.out has been redirected so that it doesn’t print to the console but to somewhere else. Take a debugger, set a breakpoint on all lines of code that call … Read more
Icon c = new ImageIcon(getClass().getClassLoader().getResource(“imgs/img_not_activated.png”)); img_etat_pharmacie.setIcon(c); 2 solved Access to resources (images) inside jars/classpath
Just Change Inner for loop : here for k=i-1 as you are checking for i>9 and i<9 so 11 will be excluded. I guess you are trying to manage space between two digit and one digit number. But you can just use single for i<=10 and double space for i>10 for (int k = 20; … Read more
For synchronizing a HashMap,you can use Collections.synchronizedMap(<your hashmap reference>) which will return a synchronized map for you, which is thread-safe. solved How to change HashMap as Synchoronized
set.add will return false if the element that you wish to add to the Set already exists in the Set (and therefore wasn’t added). Your method returns false if set.add returns false for at least one of the elements of the input List, which means is does what its name implies – checks for duplicates. … Read more
Demonstrating what the commenter said: scala> import collection.JavaConverters._ import collection.JavaConverters._ scala> val js = (1 to 10).toSet.asJava js: java.util.Set[Int] = [5, 10, 1, 6, 9, 2, 7, 3, 8, 4] scala> def f(is: collection.mutable.Set[Int]) = is.size f: (is: scala.collection.mutable.Set[Int])Int scala> def g(js: java.util.Set[Int]) = f(js.asScala) g: (js: java.util.Set[Int])Int scala> g(js) res0: Int = 10 3 … Read more
The best way I would see to do this would be to use Vectors. This is not like arrays where you need a defined size in order to proceed. Vectors can grow and shrink. See [http://docs.oracle.com/javase/7/docs/api/java/util/Vector.html] for more details. Basing this off the code you have already given I would recommend the following: import java.util.*; … Read more
The only way the problem can exist given the posted code, if the reported exception/line is correct, is when “Somerecords” is not really creating a List<Object[]> object – but a List containing non-Object[] elements. One reason could be the method in question is typed to return a non-generic List, filled with double values. Java will … Read more
Your question isn’t clear, but I suspect the main point you may be missing is that ListIterator.add inserts at the current location: The element is inserted immediately before the next element that would be returned by next(), if any, and after the next element that would be returned by previous(), if any. And also: The … Read more
I guess that you want the list of keys sorted. If your hashmap is called h, then try this: SortedSet<String> sortedKeys = new TreeSet<String>(h.keySet()); 4 solved How to sort hashmap? [closed]
You cannot nest method declarations. However, you can simply define them separately and call one from the other. That is the purpose of functions. public static boolean divides(int num, int denom) { if (num%denom==0) return true; else return false; } public static boolean isLeapYear(int year) { return divided(x, y); // not sure what you are … Read more
Your main-method is the static context, and you are trying to call the non-static method display() from it. That doesn’t work even if it is in the same class. To have the disply method non-static you have to do this. public static void main(String[] args) throws FileNotFoundException{ ReverseLL r = new ReverseLL(); r.display(head); } public … Read more