Java Study Notes (1) Java Introduction

JavaIs a class (Class).ProgramAnd it is hard to specify that the root nodes of all classes areObjectAnd the rest are their child classes.

JavaOnly single inheritance is supported, that is, a class can only have one parent class.

JavaNot only is it an object-orientedProgramming LanguageIn addition to object data types, basic data types are also supported, such as integer, real, complex, and Boolean.

JavaThe programming interface of the language is supported.HTTPAndFTPAnd so onTCP/IPProtocol Class Library,JavaThe application can useURLThe address directly accesses objects on the network, just like accessing local objects.

JavaCompile and then explain the execution.

. Java File -- (Compilation) -->. Class File ( Also known as bytecode files / Virtual MachineCode ) -- (Java The loader will . Class File loading memory ) --- (Java The bytecode validator performs a security check on the security of the bytecode. ) ---> JAVA The interpreter interprets the execution bytecode.

JavaThe robustness of the language is embodied in :(1.

(2) Introduces the exception handling mechanism.

JavaSupports multithreading. To avoid system deadlocks caused by resource conflicts,JavaIntroduced synchronization keywordsSynchronizedTo specify that a method or object cannot be concurrently executed.

Process (Process): A process has its own memory space and system resources during execution. The memory data and status of each process are isolated from each other, and data exchange is completed through specific communication mechanisms, such as pipelines.

Thread (Thread): A thread is a lightweight process generated in the process. A thread shares a piece of memory space and a group of system resources during execution. Therefore, data can be directly exchanged between threads.