Detailed explanation of the core JVM framework in the Java class library
Detailed explanation of the core JVM framework in the Java class library
JVM (Java virtual machine) is the core framework of Java, which provides the environment and runtime support for code execution.The JVM framework plays an important role in the development of Java. It is not only responsible for explaining and executing the Java bytecode, but also provides many core libraries and tools to manage memory, perform multi -threaded, and carry out garbage recycling.
In this article, we will discuss the core JVM framework in the Java class library in detail and provide some Java code examples to deepen understanding.
1. Classloader:
The class loader is a core function of JVM. It is responsible for loading the Java bytecode file (.class file) to the memory and generated the corresponding class object.There are three built -in loaders in JVM: starting class loaders, extended loaders, and application class loaders.
The following is a simple example. Demonstration of how to use the ClassLoader dynamic loading class:
ClassLoader classLoader = MyClass.class.getClassLoader();
Class<?> myClass = classLoader.loadClass("com.example.MyClass");
2. Runtime Data Area during runtime:
Data area is the memory area where JVM is used to store various running data.It contains the method area, heap, stack, programmeter and local method stack.
The following is an example that shows how to use the stacks and stacks in the data area when running at the runtime:
public class RuntimeDataAreaExample {
public static void main(String[] args) {
// Declaration object reference
String s1, s2;
// Create a string object in the pile
s1 = new String("Hello");
// Copy the references of S1 to S2
s2 = s1;
// Modify the value of S1
s1 = s1.concat(" World");
System.out.println("s1: " + s1);
System.out.println("s2: " + s2);
}
}
3. Garbage Collector:
The garbage recovery is part of the JVM and is responsible for automatic recycling memory space that is no longer used.It tracks the reference relationship of the object and releases memory when the object cannot reach.
The following is a simple example, showing the use of garbage recychers:
public class GarbageCollectorExample {
public static void main(String[] args) {
MyClass obj1 = new MyClass();
MyClass obj2 = new MyClass();
obj2 = null;
// Manually call the garbage recycle
System.gc();
}
}
4. Thread:
The thread is the basic unit for implementing concurrent execution in JVM.JVM provides Thread class and related class libraries for creating and managing threads.
The following is an example that creates and starts a new thread:
public class ThreadExample {
public static void main(String[] args) {
Thread myThread = new Thread(new MyRunnable());
// Starting thread
myThread.start();
}
}
class MyRunnable implements Runnable {
@Override
public void run() {
// The code executed by the thread
System.out.println("Thread running...");
}
}
The above is a brief introduction to some important aspects of the JVM core framework in the Java library.These frameworks provide powerful functions to help developers build high -efficiency and stable Java applications.Through in -depth understanding of these frameworks, and using the appropriate Java class library, you can better use the ability of JVM and improve the performance and maintenance of the program.
