{"id":1235,"date":"2022-02-26T06:20:13","date_gmt":"2022-02-26T06:20:13","guid":{"rendered":"https:\/\/mdr.foobrdigital.com\/?p=1235"},"modified":"2022-02-26T06:20:13","modified_gmt":"2022-02-26T06:20:13","slug":"java-enums","status":"publish","type":"post","link":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/2022\/02\/26\/java-enums\/","title":{"rendered":"Java enums"},"content":{"rendered":"\n

In this tutorial, we will learn about enums in Java. We will learn to create and use enums and enum classes with the help of examples.<\/p>\n\n\n\n

In Java, an enum (short for enumeration) is a type that has a fixed set of constant values. We use the enum<\/code> keyword to declare enums. For example,<\/p>\n\n\n\n

enum Size { \n   SMALL, MEDIUM, LARGE, EXTRALARGE \n}<\/code><\/pre>\n\n\n\n
Here, we have created an enum named Size<\/var>. It contains fixed values SMALL<\/var>, MEDIUM<\/var>, LARGE<\/var>, and EXTRALARGE<\/var>.<\/p>\n\n\n\n
These values inside the braces are called enum constants (values).<\/p>\n\n\n\n
Note:<\/strong> The enum constants are usually represented in uppercase.<\/p>\n\n\n\n
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Example 1: Java Enum<\/h3>\n\n\n\n
enum Size {\n   SMALL, MEDIUM, LARGE, EXTRALARGE\n}\n\nclass Main {\n   public static void main(String[] args) {\n      System.out.println(Size.SMALL);\n      System.out.println(Size.MEDIUM);\n   }\n}<\/code><\/pre>\n\n\n\n
Output<\/strong><\/p>\n\n\n\n
SMALL\nMEDIUM<\/samp><\/pre>\n\n\n\n
As we can see from the above example, we use the enum name to access the constant values.<\/p>\n\n\n\n
Also, we can create variables of enum types. For example,<\/p>\n\n\n\n
Size pizzaSize;<\/code><\/pre>\n\n\n\n
Here, pizzaSize<\/var> is a variable of the Size<\/var> type. It can only be assigned with 4 values.<\/p>\n\n\n\n
pizzaSize = Size.SMALL;\npizzaSize = Size.MEDIUM;\npizzaSize = Size.LARGE;\npizzaSize = Size.EXTRALARGE;<\/code><\/pre>\n\n\n\n
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Example 2: Java Enum with the switch statement<\/h3>\n\n\n\n
enum Size {\n SMALL, MEDIUM, LARGE, EXTRALARGE\n}\n\nclass Test {\n Size pizzaSize;\n public Test(Size pizzaSize) {\n   this.pizzaSize = pizzaSize;\n }\n public void orderPizza() {\n   switch(pizzaSize) {\n     case SMALL:\n       System.out.println(\"I ordered a small size pizza.\");\n       break;\n     case MEDIUM:\n       System.out.println(\"I ordered a medium size pizza.\");\n       break;\n     default:\n       System.out.println(\"I don't know which one to order.\");\n       break;\n   }\n }\n}\n\nclass Main {\n public static void main(String[] args) {\n   Test t1 = new Test(Size.MEDIUM);\n   t1.orderPizza();\n }\n}<\/code><\/pre>\n\n\n\n
Output<\/strong><\/p>\n\n\n\n
I ordered a medium size pizza.<\/samp><\/pre>\n\n\n\n
In the above program, we have created an enum type Size<\/var>. We then declared a variable pizzaSize<\/var> of the Size<\/var> type.<\/p>\n\n\n\n
Here, the variable pizzaSize<\/var> can only be assigned with 4 values (SMALL<\/var>, MEDIUM<\/var>, LARGE<\/var>, EXTRALARGE<\/var>).<\/p>\n\n\n\n
Notice the statement,<\/p>\n\n\n\n
Test t1 = new Test(Size.MEDIUM);<\/code><\/pre>\n\n\n\n
It will call the Test()<\/code> constructor inside the Test<\/var> class. Now, the variable pizzaSize<\/var> is assigned with the MEDIUM<\/var> constant.<\/p>\n\n\n\n
Based on the value, one of the cases of the switch case statement<\/a> is executed.<\/p>\n\n\n\n
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Enum Class in Java<\/h2>\n\n\n\n
In Java, enum types are considered to be a special type of class. It was introduced with the release of Java 5.<\/p>\n\n\n\n
An enum class can include methods and fields just like regular classes.<\/p>\n\n\n\n
enum Size {\n    constant1, constant2, \u2026, constantN;\n\n    \/\/ methods and fields\t\n}<\/code><\/pre>\n\n\n\n
When we create an enum class, the compiler will create instances (objects) of each enum constants. Also, all enum constant is always public static final<\/code> by default.<\/p>\n\n\n\n
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Example 3: Java Enum Class<\/h3>\n\n\n\n
enum Size{\n  SMALL, MEDIUM, LARGE, EXTRALARGE;\n\n  public String getSize() {\n\n    \/\/ this will refer to the object SMALL\n    switch(this) {\n      case SMALL:\n        return \"small\";\n\n      case MEDIUM:\n        return \"medium\";\n\n      case LARGE:\n        return \"large\";\n\n      case EXTRALARGE:\n        return \"extra large\";\n\n      default:\n        return null;\n      }\n   }\n\n  public static void main(String[] args) {\n\n    \/\/ call getSize()\n    \/\/ using the object SMALL\n    System.out.println(\"The size of the pizza is \" + Size.SMALL.getSize());\n  }\n}<\/code><\/pre>\n\n\n\n
Output<\/strong><\/p>\n\n\n\n
The size of the pizza is small<\/samp><\/pre>\n\n\n\n
In the above example, we have created an enum class Size<\/var>. It has four constants SMALL<\/var>, MEDIUM<\/var>, LARGE<\/var> and EXTRALARGE<\/var>.<\/p>\n\n\n\n
Since Size<\/var> is an enum class, the compiler automatically creates instances for each enum constants.<\/p>\n\n\n\n
Here inside the main()<\/code> method, we have used the instance SMALL<\/var> to call the getSize()<\/code> method.<\/p>\n\n\n\n
Note<\/strong>: Like regular classes, an enum class also may include constructors. To learn more about it, visit Java enum constructor<\/a>.<\/p>\n\n\n\n
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Methods of Java Enum Class<\/h2>\n\n\n\n
There are some predefined methods in enum classes that are readily available for use.<\/p>\n\n\n\n
1. Java Enum ordinal()<\/h3>\n\n\n\n
The ordinal()<\/code> method returns the position of an enum constant. For example,<\/p>\n\n\n\n
ordinal(SMALL) \n\/\/ returns 0<\/code><\/pre>\n\n\n\n
2. Enum compareTo()<\/h3>\n\n\n\n
The compareTo()<\/code> method compares the enum constants based on their ordinal value. For example,<\/p>\n\n\n\n
Size.SMALL.compareTo(Size.MEDIUM)\n \/\/ returns ordinal(SMALL) - ordinal(MEDIUM)<\/code><\/pre>\n\n\n\n
3. Enum toString()<\/h3>\n\n\n\n
The toString()<\/code> method returns the string representation of the enum constants. For example,<\/p>\n\n\n\n
SMALL.toString()\n\/\/ returns \"SMALL\"<\/code><\/pre>\n\n\n\n
4. Enum name()<\/h3>\n\n\n\n
The name()<\/code> method returns the defined name of an enum constant in string form. The returned value from the name()<\/code> method is final<\/code>. For example,<\/p>\n\n\n\n
name(SMALL)\n\/\/ returns \"SMALL\"<\/code><\/pre>\n\n\n\n
5. Java Enum valueOf()<\/h3>\n\n\n\n
The valueOf()<\/code> method takes a string and returns an enum constant having the same string name. For example,<\/p>\n\n\n\n
Size.valueOf(\"SMALL\")\n\/\/ returns constant SMALL.<\/code><\/pre>\n\n\n\n
6. Enum values()<\/h3>\n\n\n\n
The values()<\/code> method returns an array of enum type containing all the enum constants. For example,<\/p>\n\n\n\n
Size[] enumArray = Size.value();<\/code><\/pre>\n\n\n\n
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Why Java Enums?<\/h2>\n\n\n\n
In Java, enum was introduced to replace the use of int constants<\/strong>.<\/p>\n\n\n\n
Suppose we have used a collection of int<\/code> constants.<\/p>\n\n\n\n
class Size {\n   public final static int SMALL = 1;\n   public final static int MEDIUM = 2;\n   public final static int LARGE = 3;\n   public final static int EXTRALARGE = 4;\n}<\/code><\/pre>\n\n\n\n
Here, the problem arises if we print the constants. It is because only the number is printed which might not be helpful.<\/p>\n\n\n\n
So, instead of using int constants, we can simply use enums. For example,<\/p>\n\n\n\n
enum Size {\n   SMALL, MEDIUM, LARGE, EXTRALARGE\n}<\/code><\/pre>\n\n\n\n
This makes our code more intuitive.<\/p>\n\n\n\n
Also, enum provides compile-time type safety<\/strong>.<\/p>\n\n\n\n
If we declare a variable of the Size<\/var> type. For example,<\/p>\n\n\n\n
Size size;<\/code><\/pre>\n\n\n\n
Here, it is guaranteed that the variable will hold one of the four values. Now, If we try to pass values other than those four values, the compiler will generate an error.<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
In this tutorial, we will learn about enums in Java. We will learn to create and use enums and enum classes with the help of examples. In Java, an enum (short for enumeration) is a type that has a fixed set of constant values. We use the enum keyword to declare enums. For example, Here, we have […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[556],"tags":[],"_links":{"self":[{"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/posts\/1235"}],"collection":[{"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/comments?post=1235"}],"version-history":[{"count":0,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/posts\/1235\/revisions"}],"wp:attachment":[{"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/media?parent=1235"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/categories?post=1235"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/tags?post=1235"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}