Learn about the architecture and module of the Core framework in the Java class library

The architecture and module of the Core framework in the Java class library The Core framework in the Java class library is the foundation and core part of the development of Java. It provides many important classes and functions, which is an indispensable part of the Java development process.Core framework architecture and module division is very important for understanding the overall structure and usage of the Java class library. The Core framework of the Java class library mainly includes the following modules: 1. Java.lang: This is the core module in the Java class library, which provides the basic and abnormal class of Java language.These include some of the most basic categories, such as Object, String, etc., as well as some common interfaces, such as Runnable, Comparable, etc.In addition, the Java.lang module also provides the class Main method where the inlet point of the Java program is located, as well as Throwable, Exception, etc. that are related to abnormal processing. The following is a simple example code, which demonstrates the use of String in the Java.lang module: public class Example { public static void main(String[] args) { String greeting = "Hello, World!"; System.out.println(greeting); } } 2. Java.util: This module provides many commonly used practical tool categories and data structures.For example, the collection classes such as ArrayList, HashMap are Java.util modules, and are commonly used in data storage and processing in Java programs.In addition, the Java.util module also provides date and time processing, random number generation, international support category, etc. The following is an example code that shows the use of the ArrayList class in the Java.util module: import java.util.ArrayList; public class Example { public static void main(String[] args) { ArrayList<String> fruits = new ArrayList<>(); fruits.add("Apple"); fruits.add("Banana"); fruits.add("Orange"); System.out.println(fruits); } } 3. Java.io: This module provides the input and output function of the Java program.In the IO operation of files and networks, the class and interfaces in the Java.io module are very useful tools.The commonly used classes include File, InputStream, OutputStream, etc., which can be used to read and write files and data streams. The following is an example code that shows the use of file class in the java.io module: import java.io.File; public class Example { public static void main(String[] args) { File file = new File("example.txt"); System.out.println("File exists: " + file.exists()); } } In addition to the above modules, the Core framework of the Java class library also includes many other important modules, such as Java.math for high -precision numerical calculations, Java.net for network programming, Java.SQL for database access, etc. To sum up, the structural and module division of the Core framework in the Java class library provides rich functions and tools for developers.By familiar with and using these modules, developers can develop Java programs more efficiently and can handle various common programming tasks.