public class ServiceFactory { private static ServiceFactory instance; private final DishService dishService = new DishService(); private final OrderService orderService = new OrderService(); private final UserService userService = new UserService(); private ServiceFactory() { } public static synchronized ServiceFactory getInstance() { if (instance == null) instance = new ServiceFactory(); return instance; } public DishService getDishService() { return… Read More Does this class comply to Factory method pattern?

I need to create program to offer the user the ability to produce the report as show about in alphabetical order by township name or in size order by township square mile. But I get error message when I run the text file with the code. Without the text file, my code works, but when… Read More Error message when I attach a textfile to my code

import java.util.*; public class tryAgain { public static void main(String[] args) { Scanner sc = new Scanner (System.in); //Creating array with Children object Children[] ages = new Children[5]; //Creating new Children ages and adding em to counter ages[0] = new Children(12); ages[1] = new Children(10); ages[2] = new Children (13); ages[3] = new Children(9); ages[4]… Read More Type mismatch: cannot convert from Object Array to int

Please let me know how output of below java code is defined Map m=new HashMap(); m.put("A", "B"); m.put("A", m.put("A", "C")); output: A,B till 2nd line it is A,B after going in m.put("A","C") it is becoming A,C last m.put("A", m.put("A", "C")); is taking key as "A" and value as "B" please let me know how it… Read More How output defined in java map put?

public class Main { public static void main(String[] args) { Vehicle vehicle = new Vehicle(); vehicle = (car) Vehicle; } } class Vehicle { static void transport() { } } class Car extends Vehicle { int age; String brand; } i understand that java implicitly upcasts, but I want to downcast this Vehicle instance and… Read More How can I downcast this object in java?

I have a static method in which I want to write something to a file, but it keeps rewriting the whole file. public static void log(Class called, String functionName, String problem) { try { BufferedWriter bw = new BufferedWriter(new FileWriter("log.txt")); bw.append(LocalDateTime. now() + " – " + called.getCanonicalName() + " – " + functionName +… Read More Appending to file in static methods keep rewriting the whole file in Java

I want to sort a Map by value length. For example, I have this code: public static void main(String[] args) { Map<Integer, Map<Integer, Integer>> map = new HashMap<>(); Random random = new Random(); for (int i = 0; i < 5; i++) { Map<Integer, Integer> mapA = new HashMap<>(); for (int j = 0; j… Read More Sort a Map<Integer, Map<Integer, Integer>> by value length

In this code, we have to add a method set() which will take two parameters, an (int) index, and an Integer value, which will set the array element at the specified index to the specified value and the array will grow if an attempt is made to set a value beyond the end of the… Read More function execution in java program

Ive been trying to figure this out for awhile now and just cant quite understand how im meant to create the expected outputs. Ive managed to get the input and maximum number of Unique permutations, all i need now is to find out how to get the expected strings as outputs. Im assuming that there… Read More Permutation of Strings within an ArrayList (Using Recursion)

I have to reverse the given string and parse it with "-". for eg. INPUT: abcde OUTPUT : e-d-c-b-a Any simple solutions? >Solution : Using StringBuilder#reverse we can try: String input = "abcde"; StringBuilder sb = new StringBuilder(input); String output = sb.reverse().toString().replaceAll("(?<=.)(?=.)", "-"); System.out.println(output); // e-d-c-b-a For an explanation on the regex pattern used in… Read More JAVA : How can I reverse the string and parse it with '-' in Java