What are the differences between go language and java?

Difference: 1. Go does not allow function overloading, java does; 2. Java allows polymorphism by default, Go does not; 3. Go uses HTTP protocol for routing configuration, java does not; 4. Go code can automatically Expand to multiple cores, and Java does not always have enough scalability; 5. Java object methods will have a hidden this pointer to pass, Go does not; 6. Java does not support multiple inheritance, and Go supports multiple inheritance; 7. GO uses a non-intrusive interface, while java does not.

The operating environment of this tutorial: windows7 system, GO 1.18&&java8 version, Dell G3 computer.

1. About Java

1. The use of Java

First let’s review The main uses and application scenarios of Java:

• Use 1: Server backend system development (web backend, microservice backend payment system, business system, management backend, various backend interactions interface service).

• Use 2: The underlying implementation of the big data framework and Java API support. (Hadoop).
  

• Use three: underlying development of other middleware. (Tomcat, RocketMq, Hbase, Kafka (part), SpringCloud, Dubbo...).
  

#2. Advantages and characteristics of Java

• The server system has high performance.

• There is a virtual machine, cross-platform.

• It has powerful functions, supports many class libraries, and has many ecosystem class libraries, making development frameworks and tools easier to find.

• It has a high market share, and about 60% of Chinese programmers are doing Java-related work.

2. About Go

1. The reason for Go’s birth

Go language was developed by Google's internal company bosses. The main reason is that Google has a large number of C program projects, but the development efficiency is too low and the maintenance cost is high, so the Go language was developed to improve efficiency, and the performance is only poor. a little.

(Go was developed in 2007 and launched in 2009)

2. A macroscopic view of the differences between Go and Java

• No virtual machine, no Cross-platform (the platform here refers to the operating system) (can run multiple platforms, each platform has a different binary package), and needs to be packaged and compiled into an executable program corresponding to the server operating system version (windows/linux) (for example, windows is exe). (Note: Go cross-platform refers to cross-platform between 32-bit and 64-bit operating systems)

• Because Go programs are directly packaged into operating system executable files, there is no The virtual machine is at the intermediate conversion layer, so theoretically the execution efficiency will be higher (theoretically higher, the actual situation requires specific analysis).

• Compared with Java's language and coding style, Go is more concise and can achieve the same function with less code.

• The bottom layer of the Go language is also implemented in C, and it is designed with high concurrency (when Java was born (1995)) there were no multi-core CPUs, so its concurrency support was added later, Go (2009) was born with a computer that already had a multi-core CPU. When designing the language, it took full advantage of the performance of the multi-core CPU (Intel launched multi-core for the first time in 2005), so it has high performance and high concurrency support (high concurrency support among them refers to One is to make full use of the performance resources of multi-core CPUs. For example, the go program uses all CPUs by default (unless you set how many to use)).

• is naturally suitable for the development of some specific systems, such as blockchain systems (such as Ethereum underlying system, Ethereum upper-layer applications), cloud computing and containers (Docker, K8s underlying (all developed by go) (most of the self-developed operation and maintenance management projects of large companies also use go for the underlying development), network programming (similar to Java's Netty).

3. Specific differences between Go language and Java

1. Function overloading

Function overloading is not allowed on Go and must have unique names for methods and functions. Java allows function overloading.

2. Polymorphism

Java allows polymorphism by default. However, Go does not.

The polymorphic implementation in Java follows a principle: when a superclass object reference variable refers to a subclass object, the type of the referenced object rather than the type of the reference variable determines whose member method is called, but this is The method called must be defined in the superclass, that is, a method overridden by the subclass. Polymorphism in Java can be achieved through two methods: inheritance-based and interface-based.

The Go language generally does not allow different types of assignments, that is, it does not support traditional polymorphism. Interface is an exception and can be assigned with different types. As long as a type implements the interface, we can assign variables of that type to variables of the interface.

3. Routing configuration

Go language uses HTTP protocol for routing configuration; while java uses Akka.routing.ConsistentHashingRouter and Akka.routing.ScatterGatherFirstCompletedRouter for routing configuration.

4. Scalability

Go code can automatically scale to multiple cores; however, Java does not always have sufficient scalability.

5. Object transfer:

Object methods in Java will be passed with a hidden this pointer, while object-oriented in Go language is just expressed in a different grammatical form. There is no hidden this pointer, that is, the target imposed by the method is passed explicitly and is not hidden. In addition, the target applied by the method is not necessarily a pointer (java passes a pointer to an object). If it is a pointer, it does not need to be named this.

6. Inheritance:

Inheritance in Java is completed through the extends keyword and does not support multiple inheritance. Inheritance in Go language is completed through anonymous composition: the base class is defined in the form of Struct, and the subclass only needs to put the base class as a member in the definition of the subclass, and the memory layout can be changed by adjusting the position of the base class members, supporting multiple inheritance. .

7. Interface:

The interface in Java exists as a contract in different components and is mandatory. The class must declare that it implements an interface and needs to inherit from the interface. Even if there are two identical interfaces but only different names, whether the class implements the interface can only be determined based on whether the implementation interface declared by the class includes the interface. This is called an "intrusive" interface.

The GO language uses a non-intrusive interface. A class only needs to implement all the functions required by the interface, then we say that the class implements the interface. The GO language can perform interface query (whether the object pointed to by the interface implements another interface), type query, etc. through the interface.

【Related recommendations: Go video tutorial, Programming teaching】

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