Tutorial by Examples: d

In C++, threads are created using the std::thread class. A thread is a separate flow of execution; it is analogous to having a helper perform one task while you simultaneously perform another. When all the code in the thread is executed, it terminates. When creating a thread, you need to pass somet...

std::this_thread is a namespace which has functions to do interesting things on the current thread from function it is called from. FunctionDescriptionget_idReturns the id of the threadsleep_forSleeps for a specified amount of timesleep_untilSleeps until a specific timeyieldReschedule running threa...

At first glance it may appear that null and undefined are basically the same, however there are subtle but important differences. undefined is the absence of a value in the compiler, because where it should be a value, there hasn't been put one, like the case of an unassigned variable. undefined...

1 / 0; // Infinity // Wait! WHAAAT? Infinity is a property of the global object (therefore a global variable) that represents mathematical infinity. It is a reference to Number.POSITIVE_INFINITY It is greater than any other value, and you can get it by dividing by 0 or by evaluating the express...

When local changes are present, the git pull command aborts reporting : error: Your local changes to the following files would be overwritten by merge In order to update (like svn update did with subversion), you can run : git stash git pull --rebase git stash pop A convenient way coul...

Reachability uses NSNotification messages to alert observers when the network state has changed. Your class will need to become an observer. [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:) name:kReachabilityChangedNotification object:nil]; Elsewher...

Many IDEs provide support for generating HTML from Javadocs automatically; some build tools (Maven and Gradle, for example) also have plugins that can handle the HTML creation. However, these tools are not required to generate the Javadoc HTML; this can be done using the command line javadoc tool. ...

Functional Interfaces Lambdas can only operate on a functional interface, which is an interface with just one abstract method. Functional interfaces can have any number of default or static methods. (For this reason, they are sometimes referred to as Single Abstract Method Interfaces, or SAM Interf...

django-admin is a command line tool that ships with Django. It comes with several useful commands for getting started with and managing a Django project. The command is the same as ./manage.py , with the difference that you don't need to be in the project directory. The DJANGO_SETTINGS_MODULE envir...

// Java: String joined = things.stream() .map(Object::toString) .collect(Collectors.joining(", ")); // Kotlin: val joined = things.joinToString() // ", " is used as separator, by default

// Java: Map<Department, List<Employee>> byDept = employees.stream() .collect(Collectors.groupingBy(Employee::getDepartment)); // Kotlin: val byDept = employees.groupBy { it.department }

// Java: Map<Department, Integer> totalByDept = employees.stream() .collect(Collectors.groupingBy(Employee::getDepartment, Collectors.summingInt(Employee::getSalary))); // Kotlin: val totalByDept = employees.groupBy { it.dept }.mapValues { it.v...

// Java: Map<Boolean, List<Student>> passingFailing = students.stream() .collect(Collectors.partitioningBy(s -> s.getGrade() >= PASS_THRESHOLD)); // Kotlin: val passingFailing = students.partition { it.grade >= PASS_THRESHOLD }

// Java: Map<Person.Sex, List<String>> namesByGender = roster.stream().collect( Collectors.groupingBy( Person::getGender, Collectors.mapping( Person::getName, Collectors.toList()))); // ...

// Java: String shortest = items.stream() .min(Comparator.comparing(item -> item.length())) .get(); // Kotlin: val shortest = items.minBy { it.length }

// Java: Stream.of("a1", "a2", "a3") .findFirst() .ifPresent(System.out::println); // Kotlin: sequenceOf("a1", "a2", "a3").firstOrNull()?.apply(::println)

// Java: IntStream.range(1, 4).forEach(System.out::println); // Kotlin: (inclusive range) (1..3).forEach(::println)

// Java: Arrays.stream(new int[] {1, 2, 3}) .map(n -> 2 * n + 1) .average() .ifPresent(System.out::println); // 5.0 // Kotlin: arrayOf(1,2,3).map { 2 * it + 1}.average().apply(::println)

// Java: Stream.of("a1", "a2", "a3") .map(s -> s.substring(1)) .mapToInt(Integer::parseInt) .max() .ifPresent(System.out::println); // 3 // Kotlin: sequenceOf("a1", "a2", "a3") .map { it.substring(1) } ...

// Java: IntStream.range(1, 4) .mapToObj(i -> "a" + i) .forEach(System.out::println); // a1 // a2 // a3 // Kotlin: (inclusive range) (1..3).map { "a$it" }.forEach(::println)