Using Lombok to simplify unnecessary Java code in your project

When writing to use Java, there will inevitably be some template code to write, otherwise get/set,tostring, hashcode, close resources, define constructors and so on. The code will look very redundant and very long. Lombok project can be we get rid of these things, through a series of annotations, Lombok can help us to automatically generate these functions.

Lombok website Address: https://projectlombok.org/

Reference Document: Https://projectlombok.org/features/index.html

1. Installation

Download Lombok.jar on the website, double-click and follow the prompts to install successfully in eclipse.

If you use MAVEN, you need to introduce dependencies:

    <Dependency>         <groupId>Org.projectlombok</groupId>         <Artifactid>Lombok</Artifactid>         <version>1.16.4</version>         <Scope>Provided</Scope>     </Dependency>

If you need to compile the Java class with Javac or other command tools, you need to put Lombok.jar into classpath.

2. How to use (document: https://projectlombok.org/features/index.html)

1> @Getter/@Setter, annotations on a Pojo class, the Get/set function is automatically generated at compile time for us.

2> @ToString Annotations on the class, compile, help us to generate the ToString function including all field;

3> @EqualsAndHashCode, compile, help us generate Equlas and hashcode functions;

4> @Cleanup, annotations in the definition of some resource objects, can help us to automatically call their close () function;这个很有帮助；

5> @NoArgsContructor, @RequireArgsContructor, @AllArgsContructor, respectively, to help us generate parameterless constructors, each of the constructors of a non-null field, constructor for all field parameters;

6> @Data, all together now:a shortcut for @ToString ,, in all fields, and on all @EqualsAndHashCode @Getter non-final fields, and @Setter ! (Equivalent to: @ToString ,,, @EqualsAndHashCode @Getter @Setter , @RequiredArgsConstructor )

For more annotations, see https://projectlombok.org/features/index.html

3. Example

 Public class Test {    privateint  ID;     Private String name;     Private String password;      Public Static void Main (string[] args) {        new Test (1, "Test", "password");        SYSTEM.OUT.PRINTLN (test);        System.out.println (Test.getname ());}    }

Results:

Test (id=1, name=test, password=password) test

The constructor for the full field parameter of Test is automatically generated, and the ToString (), Get/set function and so on are generated automatically. Look at another example:

     Public Static voidMain (string[] args)throwsioexception{@Cleanup InputStream in=NewFileInputStream ("/home/a.txt"); @Cleanup OutputStream out=NewFileOutputStream ("/home/b.txt"); byte[] B =New byte[10000];  while(true) {            intR =In.read (b); if(r = =-1)                 Break; Out.write (b,0, R); }    }

@Cleanup automatically help us to close the resource by calling the close () method.

@Cleanupensure a given resource is automatically cleaned up before the code execution path exits your Scope. annotating any local variable declaration with the annotation as so @Cleanup :
@Cleanup InputStream in = new FileInputStream("some/file");
as a result, at the end of the scope of your ' re in, is in.close() called. this are guaranteed to run by the atry/finally construct.

If the type of object you ' d like to cleanup does not has a close() method, but some other no-argument method, you Canspecify the name of this method:
@Cleanup("dispose") org.eclipse.swt.widgets.CoolBar bar = new CoolBar(parent, 0);
By default, the cleanup method was presumed close() to be. A Cleanup method that takes 1 or more arguments cannot is called via @Cleanup .

@Cleanup is implemented through try/finally, if the resource's Close method is not the default close (), you can also specify the name of the Close method @cleanup ("CloseMethod"), but the shutdown method cannot have parameters. Otherwise you won't be able to use the @Cleanup.

For more reference https://projectlombok.org/features/index.html

By using Lombok, you can reduce the amount of Java code and relieve the psychological burden.

Use Lombok to simplify unnecessary Java code in your project