{"id":13451,"date":"2018-04-16T04:53:26","date_gmt":"2018-04-16T04:53:26","guid":{"rendered":"https:\/\/data-flair.training\/blogs\/?p=13451"},"modified":"2026-05-23T11:05:03","modified_gmt":"2026-05-23T05:35:03","slug":"identifiers-in-java","status":"publish","type":"post","link":"https:\/\/data-flair.training\/blogs\/identifiers-in-java\/","title":{"rendered":"Identifiers in Java – Explore the Major Rules to Declare it!"},"content":{"rendered":"

When you were born, you were given a name. Imagine what would happen if they didn\u2019t give you one? Imagine if there were no concept of names in this world? It would have been tough!<\/p>\n

You would have to specifically describe each person by their specific appearance every time you want to talk about someone.<\/p>\n

Imagine the contact names you would use then.<\/p>\n

Long story short, it would be weird and redundant.<\/p>\n

This is why the concept of naming someone has been brought to identify people.<\/p>\n

In the programming world, you also use the same techniques. These are called identifiers.<\/p>\n

Identifiers in Java<\/h3>\n

Any name that you see in a Java program, be it the class name, the function name or the variable name, each of them is an identifier.<\/p>\n

They identify or point to a certain thing in memory, be it a variable or a class. Let us take a very basic example of a Java program and find all the identifiers in it.<\/p>\n

package com.dataflair.javaidentifiers;\r\npublic class IdentifierBasics\r\n{\r\n    public void methodexample()\r\n    {\r\n        System.out.println(\"Hey there. I am learning Java at DataFlair\");\r\n    }\r\n    public static void main(String[] args) {\r\n        new IdentifierBasics().methodexample();\r\n    }\r\n}\r\n\r\n<\/pre>\n
Output:<\/strong><\/p>\n
Hey there. I am learning Java at DataFlair<\/div>\n
Let us take note of all the identifiers in this program.<\/p>\n
    \n
  1. IdentifierBasics- This is an identifier for the class.<\/li>\n
  2. methodexample()- This is an identifier for the method.<\/li>\n
  3. args- This is an identifier for the arguments to the program.<\/li>\n<\/ol>\n
    Rules for Using Java Identifiers<\/h3>\n
    As you might have expected, there are some rules for using identifiers in Java. Some of them are:<\/p>\n
      \n
    • You should only use letters and numbers while naming anything in Java. The only special characters that are allowed are the dollar sign(\u2018$\u2019) and the underscore(\u2018_\u2019).<\/li>\n
    • Even if you can use numbers, you cannot use them to start the name of the identifier. You cannot name your variable as 666devil. But you can use devil666 as a valid variable name.<\/li>\n
    • Since Java is case sensitive, the identifiers a and A are completely different. This means that you can have two different variables with the same name but different cases.<\/li>\n
    • Java does not implement a restriction on the length of the identifier. However, it is advisable to keep the name of the identifier between 2 and 18.<\/li>\n
    • Certain words have a special meaning to the compiler, such as int and class. You cannot use these as identifiers.<\/li>\n<\/ul>\n
      Best Practices for Naming Identifiers in Java<\/h3>\n
      1. Try to use a short name for the variable.<\/p>\n
      2. If representing a value by more than one word, make sure to separate it by an underscore.<\/p>\n
      3. Avoid the use of a lengthy name, as it reduces the readability of code.<\/p>\n
      4. Name the variable such that it represents the data for easy understanding.<\/p>\n
      5. Using the uppercase and lowercase letters of the same character creates confusion. Instead, use other characters.<\/p>\n
      Reserved Keywords in Java<\/h3>\n
      As we discussed, some words in Java cannot be used as identifiers. Some of them are words such as goto, const, class, void, public and so on…<\/p>\n
      This means that there is a set of words that have a special meaning to the compiler. You can not use the words as your variable names or class names.<\/p>\n
      There are also literals that have a special value. For example, true, false and null.<\/p>\n
      You can try to make use of these words as normal identifiers, but the compiler does not recognise them and will throw an error.<\/p>\n
      However, if you use an IDE, you will immediately notice the colour change in the syntax when you try to use a reserved keyword as an identifier for something else, such as a class or a variable.<\/p>\n
      Examples of Valid and Invalid Identifiers in Java<\/h3>\n
      Now that we know quite a bit about valid and invalid identifiers, let us see some examples of what identifiers should look like and what they shouldn\u2019t look like.<\/p>\n
      Some valid identifiers in Java are:<\/strong><\/p>\n
        \n
      1. _helloworld<\/li>\n
      2. hIghValue<\/li>\n
      3. Special$value<\/li>\n<\/ol>\n
        Some invalid identifiers in Java are:<\/strong><\/p>\n
          \n
        1. ^specialValue<\/li>\n
        2. 00xTrick<\/li>\n
        3. %trest<\/li>\n<\/ol>\n
          These identifiers are not correct.<\/p>\n
          Summary<\/h3>\n
          In this article, we learned about identifiers, which are a core concept in Java. We learnt about them, how they should be named and much more.<\/p>\n
          Identifiers are often a favourite topic to be asked by interviewers, so if you are applying for a job and you have Java in your resume, be prepared with these concepts, as they are the basics, and many tricky questions can be asked about this.<\/p>\n","protected":false},"excerpt":{"rendered":"
          When you were born, you were given a name. Imagine what would happen if they didn\u2019t give you one? Imagine if there were no concept of names in this world? 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