Detailed explanation of the seniority of the core framework in the Java class library
Detailed explanation of the seniority of the core framework in the Java class library
The core framework in the Java class library provides many advanced features that can help developers use the Java language for development more effectively.This article will introduce the advanced features of some core frameworks in the Java library in detail and provide relevant Java code examples.
1. Collection framework
The set framework is one of the core frameworks in the Java library, which is used to store and operate a set of objects.It provides many different types of collection classes, such as list, set, and map.Here are some advanced features of the collection framework:
-Geneics: The collection framework can provide type security during compilation by using generic types.Using generics can specify the types of objects stored in the collection, avoiding type conversion during runtime.
List<String> list = new ArrayList<String>();
list.add("Java");
list.add("Python");
String firstElement = list.get(0);
-Tourator: The iterator is used to traverse the elements in the set.It provides a consistent way to access the elements in the set, and there is no need to understand the structure inside the collection.
List<String> list = new ArrayList<String>();
// Add element to collection
Iterator<String> iterator = list.iterator();
while (iterator.hasNext()) {
String element = iterator.next();
System.out.println(element);
}
-Ambda Expressions: The introduction of Lambda expressions can simplify the use of the set framework.Through Lambda expression, the set can be operated in a simpler way.
List<Integer> list = new ArrayList<Integer>();
// Use the even number in the Lambda expression filter collection
List<Integer> evenNumbers = list.stream().filter(num -> num % 2 == 0).collect(Collectors.toList());
2. Concurrency Framework
The concurrent framework is another core framework in the Java library to achieve multi -threaded programming.It provides a set of tools and classes to manage concurrent access and synchronization of multi -threaded programs.Here are some advanced features of concurrent framework:
-Thread Pool: The thread pool is used to reuse threads and provides a thread life cycle management.It can avoid frequent creation and destruction of the expenses of threads and improve the performance of multi -threaded programs.
ExecutorService executor = Executors.newFixedThreadPool(5);
Runnable task = new MyTask();
executor.execute(task);
-Callable and Future: The Callable interface represents the task that can return the result, and the Future interface represents the result of an asynchronous task that may not be completed.They can be used in conjunction with the thread pool to achieve task submission and result acquisition.
ExecutorService executor = Executors.newSingleThreadExecutor();
Callable<Integer> task = new MyCallable();
Future<Integer> future = executor.submit(task);
Integer result = future.get();
-The synchronous collection: The concurrent framework provides some synchronous set classes, such as ConcurrenThashmap and ConcurrenTlinkedQueue, which are used to safely operate the collection in multi -threaded environments.
ConcurrentMap<String, Integer> map = new ConcurrentHashMap<String, Integer>();
map.put("Java", 1);
map.put("Python", 2);
int value = map.get("Java");
3. IO Framework
The IO framework is the core framework used to process the input and output operation in the Java library.It provides a set of classes and interfaces for reading and writing data.The following are the advanced features of some IO frameworks:
-NIO (New IO): NIO is a non -blocking IO model that provides more efficient IO operations.It introduces the concepts of buffer and channel (Channel), which can use a small number of threads to process multiple connections.
ByteBuffer buffer = ByteBuffer.allocate(1024);
FileChannel channel = FileChannel.open(Paths.get("file.txt"), StandardOpenOption.READ);
channel.read(buffer);
-Serialization: Serialization is a process that converts the object to byte sequence to store or transmit.Java's IO framework provides serialized and dependentized support, which can easily serialize the object to byte flow or serialize from the byte flow into objects.
class Person implements Serializable {
String name;
int age;
// ...
}
Person person = new Person("Tom", 25);
// Sequence the object sequence into byte array
byte[] bytes = SerializationUtils.serialize(person);
// Turn from the back serialization of byte array to object
Person deserializedPerson = SerializationUtils.deserialize(bytes);
The above -mentioned introductions are part of the high -level features of the core framework in the Java library, and there are many other useful functions and classes available for developers.Mastering these characteristics can make developers use the Java class library to develop more efficiently.
