Analysis of the core JVM framework function in the Java class library

Analysis of the core JVM framework function in the Java class library JVM (Java virtual machine) is the core component of the Java platform, which provides an execution environment for the Java program.JVM uses the core framework function in the Java library to manage tasks in memory, threads and security.This article will analyze the core JVM framework function in the Java library and provide some Java code examples. 1. Memory management: The memory management function of JVM covers garbage recovery, memory distribution and memory model.Garbage recovery is an important function of JVM. The automatic management is no longer used and the memory is released.The core framework function in the Java class library is explicitly called the garbage recovery by providing the `System.gc () method, or perform a specific cleaning operation before the object destroyed by the` Finalize () `method. Example code: // Create an object MyClass obj = new MyClass(); // Call the garbage recycling System.gc(); 2. thread management: JVM schedules and controls multi -threaded execution through thread management functions.The core framework function in the Java class library provides the `Thread` class to create and manage threads, and support the synchronization and mutual exclusion operation of threads.For example, you can use the `Join ()" method to wait for the end of the thread to execute. Example code: // Create a thread Thread thread = new Thread(() -> { // The code executed by the thread }); // Starting thread thread.start(); // Waiting for the end of the thread thread.join(); 3. Security management: JVM protects the system through security management functions to avoid potential malicious code attacks.The core framework function in the Java class library provides a security manager (`SecurityManager`) and licenses (` Permission ') to control the access of system resources.Developers can write custom security strategies to provide additional protection. Example code: // Enable the Security Manager System.setSecurityManager(new SecurityManager()); // Check the access permissions try { SecurityManager manager = System.getSecurityManager(); if (manager != null) { manager.checkPermission(new FilePermission("path/to/file.txt", "read")); } // Execute restricted operation } catch (SecurityException e) { // Treatment of abnormal safety } In summary, the core JVM framework function in the Java library covers key tasks such as memory management, thread management and security management.By using these functions, developers can more effectively write, debug and optimize the Java programs.