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Template Enum is Data Type which contains Constant Templates which are made from
● Constant Strings (which serve as Template's Names)
● list of Constants inside brackets (number of Constants and their Data Types can be different between Templates)
Template Enum must have
● Properties for storing Template's Constant when specific Template is assigned to a Variable
(if maximum number of Constants in a Template is 3 then there should be at least 3 Properties)
● Constructor for each number of Template Constants
(if there is a Template that has 3 Constants then there should be a Constructor that accepts 3 Parameters)
● Methods that can freely operate on these Properties
(not necessarily just returning Properties, they can have Input Parameters)
Template Enum can be used
● by declaring Variable of specific Enum Data Type
● and then storing any of the Enum's Template Names inside it (you don't specify parameters here)
● Constants from a Template's list are then used to call Constructor that has that number of Parameters
● Constructor sets the Enum Properties
● if some Properties are not explicitly set by the Constructor, they will be set to default values (depending on Data Type)
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Template Enum is declared by
● using Keyword enum enum
● followed by required Enum 's Name Day
● followed by required Enum 's Body { ... }
Template Enum Syntax
//===========================================================================================================
// ENUM: Day
//===========================================================================================================
enum Day {
//CONSTANT TEMPLATES WITH VARIABLE PARAMETERS AND DATA TYPES.
SUNDAY,
MONDAY ("John"),
TUESDAY ("John", 20),
WEDNESDAY,
THURSDAY,
FRIDAY (40, 50, 60),
SATURDAY;
//PROPERTIES FOR STORING ABOVE PARAMETERS THROUGH CONSTRUCTORS. PLUS ANY ADITIONAL PROPERTIES IF NEEDED.
private String name;
private int age;
private int middle;
private int end;
//CONSTRUCTOR WITH 0 PARAMETERS.
private Day() {
this.middle = 100;
}
//CONSTRUCTOR WITH 1 PARAMETER.
private Day(String name) {
this.name = name;
}
//CONSTRUCTOR WITH 2 PARAMETERS.
private Day(String name, int age) {
this.name = name;
this.age = age;
}
//CONSTRUCTOR WITH 3 PARAMETERS.
private Day(int age, int middle, int end) {
this.age = age;
this.end = end;
}
//CUSTOM METHODS THAT OPERATE ON PROPERTIES.
public String getName () { return this.name; }
public int getAge () { return this.age; }
public int getEnd () { return this.end; }
public int setAge (int age) { return this.age = age; }
}
//===========================================================================================================
// CLASS: Test
//===========================================================================================================
public class Test {
public static void main(String[] args) {
//CREATE ENUM VARIABLE WITH PREDEFINED VALUE.
Day sunday = Day.SUNDAY;
Day monday = Day.MONDAY;
Day tuesday = Day.TUESDAY;
Day friday = Day.FRIDAY;
//DISPLAY PARAMETERS.
System.out.printf("%s %n" , sunday);
System.out.printf("%s: Hello %s %n" , monday ,monday .getName());
System.out.printf("%s: %s is %d years old %n", tuesday,tuesday.getName(),tuesday.getAge());
System.out.printf("%s: (%s,%d,%d) %n" , friday ,friday .getName(),friday
.getAge(),friday.getEnd());
//CHANGE PROPERTY.
friday.setAge(1000);
System.out.println(friday + " Age = " + friday.getAge()); //1000
}
}
