Java: what is this datastruct called?

I want to have something like MOTIVE { GET_PLAYER, GET_FLAG }.

And in my object,开发者_如何学运维 I want something like

this.motive = MOTIVE.GET_PLAYER

How can I do this?

You are talking about enum.

Something like this perhaps?

/**
 * Don't use caps for a "class" name :)
 */
public enum Motive {
  GET_PLAYER,
  GET_FLAG;

}

or (with extra fields):

/**
 * Don't use caps for a "class" name :)
 */
public enum Motive {
  GET_PLAYER("Assessination Quest"),
  GET_FLAG("Capture the Flag PvP");

  private Motive(final String desc) {
     this.description = desc;
  }

  public String getDescription() {
    return description;
  }

  private final String description;
}

usage:

public final class MyClass {
    private Motive motive;

    public MyClass(final Motive motive) {
        this.motive = motive;
    }  
}

Also consider a Motive.UNKNOWN as a default case to which you can initialize fields, so you don't get possible nulls.

And switch statements can switch on enums!

One concern: You cannot compile the enum class, compile the enum-using class, change the enum class (and compile it again) and expect it to work. enums are kind-of inlined at compile time; the compiler is allowed to use in the enum-using class hard-coded "ordinals" of the enums. Always recompile both enum classes and enum-using classes so they stay in sync,

enum examples & doc