Program for smartphones and phones with built-in GPS. New Yandex service that allows you to navigate the city using your phone. Maps for mobile phones have the same functionality as regular Yandex.Maps. You can find houses, streets and other objects, view satellite images, find out information about traffic jams. In addition, you can determine your location and direction of movement (if you have a GPS receiver). To work with mobile cards, you need to download the application and install it on your phone connected to the Internet (GPRS).
Yandex maps- a program for GPS navigation using the service of the same name from Yandex. You do not need to worry about the availability of the required maps, Yandex.Maps will load them automatically for the required area. The program will notify you about traffic jams, places of accidents, and also help you find many institutions and organizations in the area you need.
A connected GPRS connection is required for the program to work!
Main features of Yandex.Maps
Shows your location and direction of travel (if there is a GPS receiver).
Building the optimal route in Moscow and the Moscow region, taking into account traffic jams.
Detailed maps of more than 130 cities in Russia, Ukraine and other countries, with streets and house numbers.
The ability to view satellite images of the area.
Provides information about traffic jams.
Can determine approximate position using cellular operator stations or Wi-Fi hotspots around you.
Shows the installation locations of traffic police cameras, road works, road accidents and other points useful for the driver.
With Yandex.Maps, you can easily find cafes, banks, hotels, cafes, restaurants and many other organizations in the right place.
It is possible to save the route, the recorded track can be uploaded to the Yandex.Maps service.
Together with other users, you can participate in the creation of a road map, you can also report the places of accidents, problems on the road by adding labels to the map.
The presence of a "night" mode of operation for the dark time of the day.
The ability to switch to full screen mode.
Work offline, without network access.
Yandex.Traffic
Yellow and red areas show traffic jams and congestion, where the average vehicle speed is less than 20 km / h. Green - free areas where cars are moving at an average speed of 30-40 km / h. The more participants in the system, the more accurate the information provided. And everyone can leave their mark on the map.
Work in the absence and access to the Internet
Make sure that the application has read / write permissions from the disk and that card caching is enabled in the settings.
Download an archive with a map of the required region.
Find the / default folder in the archive.
Move the contents of the / default folder to the / yandexmaps / (LANGUAGE CODE) folder on the mobile device (for example / yandexmaps / ru-RU or / yandexmaps / uk-UA, depending on the language specified in the settings).
The service is built in such a way that users themselves provide information about traffic jams. Install Yandex.Maps, enable the "report traffic jams" option, and you are a full member of the service. The coordinates of your device are transmitted to the server every two minutes, where they are analyzed, and based on data from many participants, the system builds a road map.
Yellow and red areas show traffic jams and congestion, where the average vehicle speed is less than 20 km / h. Green - free areas where cars are moving at an average speed of 30-40 km / h. The more participants in the system, the more accurate the information provided. And everyone can leave their mark on the map.
Download:
Yandex maps- a program for GPS navigation using the service of the same name from Yandex. You do not need to worry about the availability of the required maps, Yandex.Maps will load them automatically for the required area. The program will notify you about traffic jams, places of accidents, and will also help you find many institutions and organizations in the area you need.
A connected GPRS connection is required for the program to work!
Main features of Yandex.Maps
- Shows your location and direction of travel (if there is a GPS receiver).
- Building the optimal route in Moscow and the Moscow region, taking into account traffic jams.
- Detailed maps of more than 130 cities in Russia, Ukraine and other countries, with streets and house numbers.
- The ability to view satellite images of the area.
- Provides information about traffic jams.
- Can determine approximate position using cellular operator stations or Wi-Fi hotspots around you.
- Shows the installation locations of traffic police cameras, road works, road accidents and other points useful for the driver.
- With Yandex.Maps, you can easily find cafes, banks, hotels, cafes, restaurants and many other organizations in the right place.
- It is possible to save the route, the recorded track can be uploaded to the Yandex.Maps service.
- Together with other users, you can participate in the creation of a road map, you can also report the places of accidents, problems on the road by adding labels to the map.
- The presence of a "night" mode of operation for the dark time of the day.
- The ability to switch to full screen mode.
- Work offline, without network access.
Yandex.Traffic
Yellow and red areas show traffic jams and congestion where the average vehicle speed is less than 20 km / h. Green - free areas where cars are moving at an average speed of 30-40 km / h. The more participants in the system, the more accurate the information provided. And everyone can leave their mark on the map.
Work in the absence and access to the Internet
- Make sure that the application has read / write permissions from the disk and that card caching is enabled in the settings.
- Download an archive with a map of the required region.
- Find the / default folder in the archive.
- Move the contents of the / default folder to the folder / yandexmaps / (LANGUAGE CODE) on a mobile device (for example / yandexmaps / ru-RU or / yandexmaps / uk-UA, depending on the language specified in the settings).
The service is built in such a way that users themselves provide information about traffic jams. Install Yandex.Maps, enable the "report traffic jams" option, and you are a full member of the service. The coordinates of your device are transmitted to the server every two minutes, where they are analyzed, and based on data from many participants, the system builds a road map.
Java island on the map of Indonesia
Java island map detailed
Tourist map of Central Java
Tourist map of West Java
Tourist map of East Java
Java Map
Java on the world map is located in the Java Sea, which washes its northern coast. From the south, the island has access to the Indian Ocean. As the geographical map of Java will show, the length of the island from west to east is almost a thousand kilometers. It is the largest island in Indonesia and is home to the country's capital, Jakarta.
Any map of Java will demonstrate that about a third of its territory is occupied by rainforests and jungles. The island is administratively divided into six regions. Java detailed map contains provinces such as Banten, West Java, Central Java, East Java, Jakarta and Yogyakarta districts.
Natural attractions are represented on the island by nature reserves and numerous volcanoes. A map of Java in Russian will help you find the most famous hills of Krakatoa and Mont Brom. It is noteworthy that the last time Krkatau, located not on the island itself, but between it and Sumatra, erupted in 2008.
A map of Java with sights from Arrivo will help you to compose the best route and find all the interesting places of the island.
A set is a collection of data where you can quickly find an existing item. However, to do this, you need to have an exact copy of the required element. This type of search is not very common, since usually only some information (key) is known, by which the corresponding element can be found. For this purpose, there is a data structure that supports display, which is also called a map. The map stores key-value pairs. Each value can be found by its key. For example, a table might contain employee information records where the keys are employee IDs and the values are Employee objects.
Map interface (java.util.Map )
- Vget (KeyK)- Returns an object corresponding to the specified key, or null if the map does not contain the specified key. The key can be null.
- Vput (KeyK, ValueV)- Adds key and value to the map. If such a key already exists, then the new object replaces the previous one associated with this key. This method returns the previous value of the object, or null if the key was not previously contained in the map. The key can be null, but the value must be non-null.
- voidputAll (Mapentries)- Adds all elements of the given map to the current one.
- booleancontainsKey (Objectkey)- Returns true if the specified key is in the map.
- booleancontainsValue (Objectvalue)- Returns true if the map contains the specified value.
- Set
- Set
keySet () - Returns the map view as a set of all keys. You can remove items from this view, and the keys and their corresponding values are automatically removed from the map, but you cannot add new items. - Collection
values () - Returns the map view as a set of all values. You can remove items from this view, and the values and their corresponding keys are automatically removed from the map, but you cannot add new items.
Basic Map implementations
The Java library provides two main map implementations: the HashMap hash map and the TreeMap tree map. Both classes implement the Map interface.
Keys are randomly arranged in a hash map, and in strict order in a tree map. The hash function, or comparison function, is used only for keys, and the values corresponding to these keys are not hashed or compared.
Which card should you choose? As with sets, hashing is somewhat faster, so it is recommended to use it where the order of the keys does not matter.
The following shows how a hash map is created to store employee information. Map staff = new HashMap< String, Employee>(); // HashMap implements the Map Employee interface harry = new Employee (“Harry Hacker”); staff.put (“987-98-9996”, harry);
When adding an object to the map, its key must also be specified. In this case, the key is a string and the corresponding value is the Employee object.
To refer to an object, you need to use a key.
String s = “987-98-9996”; Employee e = staff.get (s); // reads record harry
If there is no data corresponding to the specified key in the dataset, the get () method returns null. Keys must be unique: you cannot store two values with the same key. If you call the put () method twice with the same key, then the second value will simply replace the first. In addition, the put () method returns the previous value stored with the specified key.
The remove () method removes an element from the map, and the size () method returns the number of elements in the map.
In dataset architecture, the map itself is not considered a dataset. (In other data structure architectures, a map is considered a set of pairs, or values, indexed by keys.) However, the Java library provides for the use of a map view that implements the Collection interface or one of its child interfaces.
There are three types of representations: a set of keys, a set of values (which is not a set), or a set of key-value pairs. Keys and key-value pairs form a set, since only one unique instance of a key object can be present in a map. The methods listed below return these three types of map views.
Set keySet () Collection values () Set> entrySet ()
(The members of the last set of key-value pairs are objects of the inner class Map.Entry) Note that the set of keys is not a HashSet or TreeSet, but is an object of some other class that implements the Set interface. The Set interface extends the Collection interface. Consequently , you can use the keySet () method.
For example, you can iterate over all the keys of a map:
Set keys = map.keySet (); for (String key: keys) (// key actions)
If you want to view keys and values at the same time, you can avoid having to look up values by listing all records. To do this, you can use the following code snippet:
For (Map.Entry entry: staff.entrySet ()) (String key = entry.getKey (); Employee value = entry.getValue (); // actions with key and value)
Special Map implementations
Hash cards with lax caching
The WeakHashMap class of hash maps with loose caching was designed to solve an interesting problem. What happens to a value whose key is no longer used in the program, for example, because the last reference to that key has disappeared? In this case, it is no longer possible to access the value object. And since this key is no longer contained anywhere in the program, there is no way to remove its key-value pair from the map. But why can't it be removed by the garbage collection system, which is responsible for removing unused objects?
Unfortunately, it’s not that simple. A garbage collector in the memory management system keeps track of live objects. While the map object is active, all map cells are also active. Thus, the program itself must take care of removing unused values from active maps. This is what the WeakHashMap class is for. This data structure interacts with the garbage collection system to remove those key-value pairs for which the only key reference is a hash table entry.
This is how this mechanism works. The WeakHashMap class uses weak references to store keys. The WeakReference object contains a reference to another object, i.e. in this case, the hash table key. Typically, if garbage collection finds that there are no references to an object, that object is discarded. And if the only object reference is of type WeakReference, this lax reference is queued. It periodically checks for new links in the queue, as this means that this key is no longer used and its object can be deleted. Thus, the WeakHashMap class removes the value corresponding to this key.
Linked hash cards
In JDK 1.4, the LinkedHashSet and LinkedHashMap classes were proposed that remember the sequence in which new items are inserted into a dataset. Thus, the order of the items in the table no longer looks random. As records are added to the table, they form a doubly linked list.
Consider, for example, a map:
Map staff = new LinkedHashMap (); Staff.put (“144-25-5464”, new Employee (“Amy Lee”)); Staff.put (“567-24-2546”, new Employee (“Harry Hacker”)); Staff.put (“157-62-7935”, new Employee (“Gary Cooper”)); Staff.put (“456-62-5527”, new Employee (“Francesca Cruz”));
The staff.ketSet (). Iterator () will list its keys in the following order: 144-25-5464 567-24-2546 157-62-7935 456-62-5527
And the staff.values (). Iterator () will enumerate its values like this: Amy Lee Harry Hacker Gary Cooper Francesca Cruz
A coherent hashmap can remember the access order and take it into account when iterating over the elements. Each time you call get () or put (), the entry it touches is removed from its position and moved to the end of the linked list. These operations change the structure of the linked list, but not the cells of the hash table. The record remains in the cell that corresponds to the hash code of the key. In order to create such a hash map, you need to use the following expression:
LinkedHashMap
Knowing the access order is necessary, for example, to create a "last used" cache. For example, you may need to store the most frequently used records in memory, and retrieve the ones that you rarely need to work with from the database. If you cannot find a record in the table, and the table is already full, you can use the iterator to delete the first few elements. These elements are used less often than others.
Hash cards with individual hashing
JDK 1.4 adds another custom class, IdentityHashMap, that does custom hashing. The hash codes of the keys in it are calculated not by the hashCode () method, but by the System.identityHashCode () method. This method calculates the hash code at the address of the object in memory. In addition, the IdentityHashMap class uses the == operator rather than the equals () method to compare objects.
In other words, different objects are considered to be different from each other, even if their contents are the same. This class is useful for implementing algorithms for traversing objects (for example, for serialization), in which you need to keep track of even those objects that have already been traversed by the iterator.
Using Collections in Map
Unmodifiable views
The Collections class contains methods that create unmodifiableviews of datasets. These views are used to check the existing set, which is performed at the stage of the program operation. When an attempt is made to modify a set, an exception is thrown and the data set remains unchanged.
To obtain unmodifiable Map views, the following methods are used:
Collections.unmodifiableMap Collections.unmodifiableSortedMap
For example, suppose you want a piece of your code to view, but not touch, the contents of a dataset. To do this, follow these steps:
Map
The Collections.unmodifiableMap method returns an instance of the class that implements the Map interface. The accessor of this class retrieves values from the staff set. Obviously, the lookAt () method can call all methods declared in the Map interface. However, all modifying methods are overridden so that instead of accessing the base set, they throw an UnsupportedOperationException.
A non-modifying view does not make the dataset itself immutable. You can modify the set using a regular link (in our case, it is staff), while the methods that modify the elements of the set remain available.
Synchronized views
If you are accessing a dataset from multiple streams, care must be taken not to damage the information in the dataset. This will inevitably happen if, for example, one thread tries to include an element in the hash table, while the other tries to regenerate it.
Instead of implementing thread-safe dataset classes, the library developers chose to use the view engine for this. For example, the static method synchronizedMap () of the Collections class can convert any map to a Map with synchronized accessors.
HashMap
You can now access the map object from different threads. Methods such as get () and put () are serialized: each method must complete its entire work before another thread can call a similar method.
When developing a program, you need to make sure that no thread accesses the data structure through the usual de-synchronized methods. The easiest way to ensure this is to not store any references to the underlying object.
Hashtable and Dictionary classes
The traditional Hashtable class serves the same purpose as HashMap and has essentially the same interface. Like the methods of the Vector class, the methods of the Hashtable class are synchronized. If you do not need to provide synchronization or code compatibility for previous versions of the Java platform, then you should use the HashMap class. The Dictionary class is the abstract parent class of the Hashtable.
