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what is java thread pool

Thread pools are a form of multi-threading in which tasks are added to a queue and then automatically started when threads are created. There are many benefits of using a thread pool, such as saving system resource overhead, saving time in creating and destroying threads, etc. When we need to process more tasks, we can use the thread pool.

Nov 13, 2019 am 09:23 AM

java Thread Pool

How to synchronize Java

Since every object in Java has a built-in lock, when the method is modified with the synchronized keyword, the built-in lock will protect the entire method. Before calling the method, you need to obtain the built-in lock, otherwise it will be blocked. The statement block modified by this keyword will automatically be added with a built-in lock to achieve synchronization.

Nov 12, 2019 pm 05:59 PM

java Synchronize

How to serialize in java

First create an object and implement the Serializable interface, and then use the object stream to write a tool class for saving and reading objects.

Nov 12, 2019 pm 05:44 PM

java Serialization

How to escape in java

Java's method of escaping: Add "\" before the character that needs to be escaped to escape, so that the character has different semantics than when the character appears alone; for example: "\0" means a null character, " \t" represents horizontal tabulation, "\n" represents line feed, "\r" represents carriage return, "\b" represents backspace, etc.

Nov 12, 2019 pm 05:26 PM

java escape

What is factory pattern in java

There are three types of factory method patterns: ordinary factory pattern, which is to establish a factory class and create instances of some classes that implement the same interface. The multiple factory method pattern is an improvement on the ordinary factory method pattern. The static factory method pattern makes the methods in multiple factory method patterns static. There is no need to create an instance and can be called directly.

Nov 12, 2019 pm 05:16 PM

java Factory pattern

What is an abstract class in java

Methods modified by abstract are called abstract methods; classes modified by abstract are called abstract classes. An abstract class cannot be instantiated because it is not a concrete class, or such a class is not complete enough to directly use the new keyword to call its constructor to generate an object of this class.

Nov 12, 2019 pm 05:04 PM

java abstract class

What is mapping in java

If we want to know information about certain keys and want to find the elements corresponding to them. The map data structure is designed for this purpose. Maps are used to store key/value pairs. If the key is provided, the value can be looked up. There is a one-to-one correspondence between them.

Nov 12, 2019 pm 04:57 PM

java mapping

How to initialize java array

Static initialization: During initialization, the programmer specifies the initial value of each array element, and the system determines the length of the array. arrayName=new type[]. Dynamic initialization: The programmer specifies the length of the array during initialization, and the system initializes the default value of each array element. arrayName=new type[].

Nov 12, 2019 pm 04:44 PM

java initialization array

What are the differences between java locks?

The difference between Java locks: fair locks and unfair locks, reentrant locks, exclusive locks and shared locks, mutual exclusion locks and read-write locks, optimistic locks and pessimistic locks, segmented locks, biased locks, lightweight locks and Heavyweight lock, spin lock.

Nov 12, 2019 pm 04:31 PM

java the difference Lock

How to break out of a loop in java

There are three ways to break out of a loop in Java: break: The default is to jump out of the innermost loop, which is the closest loop where break is located. continue: Terminates this cycle and continues the next cycle. return: End the current method.

Nov 12, 2019 pm 04:12 PM

java Break out of loop

How to completely uninstall Java

The method to completely uninstall Java is: 1. Delete the configured environment variables; 2. Uninstall JavaSE; 3. Delete all Java-related folders in the C drive; 4. Delete the JavaSoft folder in the registry; 5. Restart the computer.

Nov 12, 2019 pm 04:11 PM

java method

What does this in java mean?

This in java represents the class instance itself. Usage of this: (1) Represents a reference to the current object; (2) Represents a member variable of the class, not a function parameter. Pay attention to distinguishing between function parameters and member variables when they have the same name; (3) Used for reference in the constructor A constructor that satisfies the specified parameter types.

Nov 12, 2019 pm 03:52 PM

java this

What is a class in java

A class is a collection of entities with some common characteristics. It is an abstract data type, which is an abstraction of entities with the same characteristics. In object-oriented programming languages, a class is an abstraction of the properties and behavior of a type of "thing".

Nov 12, 2019 pm 03:46 PM

java kind

what is exception in java

An Exception in Java, also known as an exception, is an event that occurs during program execution and interrupts the normal instruction flow of the executing program. In order to handle running errors in the program promptly and effectively, exception classes must be used.

Nov 12, 2019 pm 03:39 PM

java abnormal