Java中的类 getEnumConstants() 方法和示例

Java.lang.Class 类的getEnumConstants()方法用于获取该类的Enum 常量。该方法以对象数组的形式返回该类的枚举常量，该对象数组包含该类表示的枚举类。

句法：

public T[] getEnumConstants()

参数：此方法不接受任何参数

返回值：该方法以枚举对象数组的形式返回该类的指定枚举常量。

下面的程序演示了 getEnumConstants() 方法。

示例 1：

// Java program to demonstrate
// getEnumConstants() method
  
import java.util.*;
  
enum A {}
  
public class Test {
  
    public Object obj;
  
    public static void main(String[] args)
    {
  
        // returns the Class object for this class
        Class myClass = A.class;
  
        System.out.println("Class represented by myClass: "
                           + myClass.toString());
  
        // Get the Enum constants of myClass
        // using getEnumConstants() method
        System.out.println(
            "Enum constants of myClass: "
            + Arrays.toString(
                  myClass.getEnumConstants()));
    }
}

输出：

Class represented by myClass: class A
Enum constants of myClass: []

示例 2：

// Java program to demonstrate
// getEnumConstants() method
  
import java.util.*;
  
enum A {
    RED,
    GREEN,
    BLUE;
}
  
class Main {
  
    private Object obj;
  
    public static void main(String[] args)
    {
  
        try {
  
            // returns the Class object for this class
            Class myClass = A.class;
  
            System.out.println("Class represented by myClass: "
                               + myClass.toString());
  
            // Get the Enum constants of myClass
            // using getEnumConstants() method
            System.out.println(
                "Enum constants of myClass: "
                + Arrays.toString(
                      myClass.getEnumConstants()));
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出：

Class represented by myClass: class A
Enum constants of myClass: [RED, GREEN, BLUE]

参考： https://docs.oracle.com/javase/9/docs/api/ Java/lang/Class.html#getEnumConstants–