Java Getter 和 Setter

Question

Is there a better standard way to create getters and setters in Java?

It is quite verbose to have to explicitly define getters and setters for each variable. Is there a better standard annotations approach?

Does Spring have something like this?

Even C# has properties.

Answer 1

I'm not sure if you'd consider it 'standard', but Project Lombok addresses this problem. They use annotations to replace much of the verbosity of Java.

Some people are looking at alternative Java sibling languages, such as Groovy or Scala. I'm afraid it will take some years -if at all- before the JSR figures out a "standardized" way to "fix" this in Java proper.

Answer 2

Eclipse 有一个上下文菜单选项，可以为您自动生成这些选项，我相信许多其他 IDE 都会这样做。

Answer 3

I've created some annotations that are not eclipse-specific.

See http://code.google.com/p/javadude/wiki/Annotations

For example:

package sample;

import com.javadude.annotation.Bean;
import com.javadude.annotation.Property;
import com.javadude.annotation.PropertyKind;

@Bean(properties={
    @Property(name="name"),
    @Property(name="phone", bound=true),
    @Property(name="friend", type=Person.class, kind=PropertyKind.LIST)
}) 
public class Person extends PersonGen {
}

My annotations generate a superclass; I think Lombok modifies the actual class being compiled (which is officially not supported by Sun and may break - I could be wrong about how it works, but based on what I've seen they must be doing that)

Enjoy! -- Scott

Answer 4

Most IDEs provide a shortcut for generating the code (eg Eclipse: Right click -> Source -> Generate Getters & Setters ), although I realise this is probably not the answer you are looking for.

Some IOC frameworks allow you to annotate properties so that they can be used in the context of the framework eg Tapestry IOC, and the latest Spring, I think (but this use is limted to use by the framework)

Answer 5

Here is an interesting articles about the subject: http://cafe.elharo.com/java/why-java-doesnt-need-properties-it-already-has-them/

I think properties are a shortcut but it's more a little feature than a real important feature

Answer 6

I agree that getter/setters are verbose. Project Lombok has good answer for it as suggested by others. Otherwise, you could use your IDE's capability to generate them.

Answer 7

There is also Spring Roo project with its @RooJavaBean annotation. It has also @RooToString and @RooHashCodeEquals or something like that. It generates in background an AspectJ file with proper methods.

Answer 8

With Netbeans, just start typing get or set where the getter/setter is to be replaced and call up auto complete (Ctrl+Space), it'll give you the option to generate the getter or setter. It'll also give you an option to generate a constructor as well.

Answer 9

There is no better way that's part of the language -- nothing like a "property" keyword.

One alternative, as other people have mentioned, is to use your IDE to generate them. Another, if you have a lot of objects that need this, is to write your own code generation tool that takes a base class and produces a wrapper with getters and setters.

You could also simply expose the variables as public members. However, down the road this will probably come back to hurt you, when you decide to add validation logic.

However, one final thought: unless your classes are used simply to transfer data, they probably shouldn't expose their internal state. IMO, "behavior" classes with getters and setters are a code smell.

Answer 10

As a possible alternative, have you tried Scala ? It compiles to Java bytecode, and has lots of interesting shortcuts which can make your life as a Java programmer easier.

Properties for instance:

case class Person(var name:String, 
                  var age:Int);
val p = Person("John", 4)
p.name
p.name = "Charlie"
p.name

And the output:

defined class Person
p: Person = Person(John,4)
res7: String = John
res8: String = Charlie

Answer 11

Try something like this:

@Getter @Setter private int age = 10;

More info below:

https://projectlombok.org/features/GetterSetter

Answer 12

Yeah, you are kind of out of luck. Groovy does generate them for you, but no dice in standard java. If you use Eclipse you can generate them pretty easily , as well as generate hashCode() and equals() functions.

Answer 13

In the case that you need a read-only class, take a look at Java Records. It auto-generates getters and methods like equals and hashcode. However, this feature is not stabilized and currently you can use it as an experimental feature (Probably will be stabilized on Java 16). https://dzone.com/articles/introducing-java-record

Answer 14

这是 IDE 生成重复冗长代码作为 getter/setter 的工作

Answer 15

Use your IDE to generate it for you and try to minimize the amount of getters/ setters that you have - you will likely enjoy the added benefit of immutability.

I like the C# syntax for properties, I think it's pretty and clean, and pretty clean.

Answer 16

Well, one option is don't be so afraid of public fields. For simple classes that you know will never do validation or extra work under the hood on get and set, public fields require less boilerplate, are syntactically nicer, and are more efficient.

Answer 17

If you use emacs it might be possible to define an emacs macro that does this for you. Any emacs gurus out there? :)