enum in java

public class MyClass {
  enum Level {
    LOW,
    MEDIUM,
    HIGH
  }

  public static void main(String[] args) {
    Level myVar = Level.MEDIUM; 
    System.out.println(myVar);
  }
}

public enum Day {
    SUNDAY, MONDAY, TUESDAY, WEDNESDAY,
    THURSDAY, FRIDAY, SATURDAY 
}

// A simple enum example where enum is declared 
// outside any class (Note enum keyword instead of 
// class keyword) 
enum Color 
{ 
    RED, GREEN, BLUE; 
} 
  
public class Test 
{ 
    // Driver method 
    public static void main(String[] args) 
    { 
        Color c1 = Color.RED; 
        System.out.println(c1); 
    } 
}

public enum AlertLevel {
	Undefined(0),
	Ok(1),
	Warning(2),
	Alarm(3);
}

public class DaysOfTheWeek {

    public enum Days {m, t, w, r, f, sat, s};
  	    public static void main(String[] args) {
          Days d = Days.t; 
          System.out.println(d);
          //the output would be t
        }
}

public class EnumTest {
    Day day;
    
    public EnumTest(Day day) {
        this.day = day;
    }
    
    public void tellItLikeItIs() {
        switch (day) {
            case MONDAY:
                System.out.println("Mondays are bad.");
                break;
                    
            case FRIDAY:
                System.out.println("Fridays are better.");
                break;
                         
            case SATURDAY: case SUNDAY:
                System.out.println("Weekends are best.");
                break;
                        
            default:
                System.out.println("Midweek days are so-so.");
                break;
        }
    }
    
    public static void main(String[] args) {
        EnumTest firstDay = new EnumTest(Day.MONDAY);
        firstDay.tellItLikeItIs();
        EnumTest thirdDay = new EnumTest(Day.WEDNESDAY);
        thirdDay.tellItLikeItIs();
        EnumTest fifthDay = new EnumTest(Day.FRIDAY);
        fifthDay.tellItLikeItIs();
        EnumTest sixthDay = new EnumTest(Day.SATURDAY);
        sixthDay.tellItLikeItIs();
        EnumTest seventhDay = new EnumTest(Day.SUNDAY);
        seventhDay.tellItLikeItIs();
    }
}

// Java program to demonstrate that enums can have constructor 
// and concrete methods. 
  
// An enum (Note enum keyword inplace of class keyword) 
enum Color 
{ 
    RED, GREEN, BLUE; 
  
    // enum constructor called separately for each 
    // constant 
    private Color() 
    { 
        System.out.println("Constructor called for : " + 
        this.toString()); 
    } 
  
    public void colorInfo() 
    { 
        System.out.println("Universal Color"); 
    } 
} 
  
public class Test 
{     
    // Driver method 
    public static void main(String[] args) 
    { 
        Color c1 = Color.RED; 
        System.out.println(c1); 
        c1.colorInfo(); 
    } 
}