{"id":12398,"date":"2018-03-31T09:24:36","date_gmt":"2018-03-31T09:24:36","guid":{"rendered":"https:\/\/data-flair.training\/blogs\/?p=12398"},"modified":"2026-05-07T16:24:03","modified_gmt":"2026-05-07T10:54:03","slug":"java-null","status":"publish","type":"post","link":"https:\/\/data-flair.training\/blogs\/java-null\/","title":{"rendered":"Java Null &#8211; 7 Unknown Facts about Null in Java"},"content":{"rendered":"<p>Before we talk about null in Java, let us go back a few steps and recall what variables in Java are.<\/p>\n<p>Well, simply speaking, they can be thought of as tumblers. And the value of those variables is the water inside the tumbler. Makes sense.<br \/>\nNow, how many types of variables were there?<\/p>\n<p>Well, classifying broadly, there were 2 types.<\/p>\n<p>1. Reference types<\/p>\n<p>2. Primitive types<\/p>\n<p>Primitive types are the ones that would hold values, and reference types are the ones that can store references.<\/p>\n<h3>Null in Java<\/h3>\n<p>Since we just read about primitive and reference types in Java, let\u2019s break down a few points.<\/p>\n<p>When primitive values do not have a value explicitly mentioned by the programmer, the default value is stored based on the data type of the variable.<\/p>\n<p>For example, an uninitialized int variable will have 0 as the default value, a boolean variable will have false as the default value, and so on\u2026<\/p>\n<p>But what will the reference variables have if they are not explicitly referencing an object in memory? Yes, you guessed it! They would store null!<\/p>\n<p>This is exactly why we need null in Java. It is used for representing references when they are not pointing to any objects in memory. It has a special purpose.<\/p>\n<p>In Java, null is a literal. It is the same as true or false. It has a special meaning. Many people confuse it with an identifier or a keyword.<\/p>\n<h3>Important Facts about Null<\/h3>\n<p>Some facts are essential to know when you are working with null in Java.<\/p>\n<ul>\n<li>Null is case-sensitive in nature. This means that you cannot expect NULL to be a \u201cliteral\u201d in Java. It&#8217;s the same as true and false. These have individual meanings.<\/li>\n<li>All reference variables have null as their default value.<\/li>\n<li>The compiler is unable to unbox null objects. It throws a NullPointerException.<\/li>\n<li>Null is not an instance of any class. Hence, a null value will return false if used with the instanceOf operator.<\/li>\n<li>Static methods are callable with a reference to the null type.<\/li>\n<li>You cannot call non-static methods with a reference of the null type.<\/li>\n<li>You can use == and != comparisons with null types in Java.<\/li>\n<\/ul>\n<h3>Java Null Pointer Exception<\/h3>\n<p>When the program tries to access a part of the memory that is not initialized by default, then the compiler throws a null pointer exception.<\/p>\n<p>Simply speaking, this is possible when you try to access the 100th element of an array of 50 elements.<\/p>\n<p><strong>These are some common causes when a null exception occurs:-<\/strong><\/p>\n<ul>\n<li>When an object that is not initialized properly tries to call the method<\/li>\n<li>When an uninitialized object tries to access the variables of the class<\/li>\n<li>When a null is passed to a function as an argument.<\/li>\n<li>When the array is null, and is trying to get the length of that array<\/li>\n<\/ul>\n<p><strong>Java example to evaluate all the facts of null:<\/strong><\/p>\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\">package com.dataflair.javanull;\r\n\r\n\r\npublic class Main\r\n{\r\n    \r\n    private static Object a;\r\n    public static void staticmethodtest()\r\n    {\r\n        System.out.println(\"This is a static method! \");\r\n    }\r\n    public void nonstaticmethodtest()\r\n    {\r\n        System.out.println(\"This is a non-static method!\");\r\n    }\r\n    public static void main(String[] args) {\r\n        Integer i = null;\/\/null is a reserved word\r\n\r\n        \/\/Returns error-&gt; Integer j=NULL;\/\/NULL is invalid.\r\n \r\n        System.out.println(\"The default value of a is \"+a);\r\n\r\n        Integer value1=null\r\n;\r\n        \/\/Returns error -&gt; int value=value1; Cannot unbox null type.\r\n \r\n        System.out.println(value1 instanceof Integer);\/\/returns false.this is because null isnt an instance of any class. \r\n        Main ob=null;\r\n        ob.staticmethodtest();\r\n        \/\/Returns error-&gt; ob.nonstaticmethodtest(); This is not possible. NullPointerException.\r\n        String a=null;\r\n        String b=null;\r\n        System.out.println(a==b);\/\/returns true;\r\n    }\r\n}\r\n<\/pre>\n<p><strong>Output:<\/strong><\/p>\n<div class=\"code-output\">false<br \/>\nThis is a static method!<br \/>\ntrue<\/div>\n<ul>\n<li><strong>We came to know about the Null Pointer Exception in Java. But now we will learn how to avoid it.<\/strong><\/li>\n<\/ul>\n<p>We know that we will encounter a null pointer exception when the compiler tries to access some data that is null.<\/p>\n<p>Any data value that is not present in memory or set to null explicitly will return a Null Pointer Exception if accessed. A primary example of this would be trying to access an index in the array that is out of bounds. Let us see this with an example.<\/p>\n<p>Program to illustrate Java NullPointerException:<\/p>\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\">package com.dataflair.javanull;\r\n\r\nimport java.util.*;\r\n\r\npublic class Main\r\n{\r\n    public static String nullreturnfunc()\r\n    {\r\n        return null;\r\n        \r\n    }\r\n    public static void main (String[] args) {\r\n        String test;\r\n        test=nullreturnfunc();\r\n        System.out.println(test.charAt(3));\r\n        \r\n        \r\n        \r\n    }\r\n}\r\n<\/pre>\n<p><strong>Output:<\/strong><\/p>\n<div class=\"code-output\">Exception in thread &#8220;main&#8221; java.lang.NullPointerException<br \/>\nat Main.main(Main.java:21)<\/div>\n<ul>\n<li><strong>Now we can either use a try-catch method or a simple if-else block to prevent these types of errors. The try-catch method is the more sensible way to do it. But both work.<\/strong><\/li>\n<\/ul>\n<p>The same program, when modified, becomes:<\/p>\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\">package com.dataflair.javanull;\r\n\r\nimport java.util.*;\r\n\r\npublic class Main\r\n{\r\n    public static String nullreturnfunc()\r\n    {\r\n        return null;\r\n        \r\n    }\r\n    public static void main (String[] args) {\r\n        String test;\r\n        test=nullreturnfunc();\r\n        if(test!=null)\r\n        System.out.println(test.charAt(3));\r\n        else\r\n        System.out.println(\"The value is null!\");\r\n        \r\n        \r\n        \r\n    }\r\n}\r\n<\/pre>\n<p><strong>Output:<\/strong><\/p>\n<div class=\"code-output\">The value is null!<\/div>\n<ul>\n<li><strong>Now we try to use try-catch to avoid null pointer exceptions.<\/strong><\/li>\n<\/ul>\n<p>We can use any kind of message we want in the catch block.<\/p>\n<p>If you are having difficulty understanding what a try-catch is, please refer to our exception handling in Java article.<\/p>\n<p>The program becomes:<\/p>\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\">package com.dataflair.javanull;\r\nimport java.util.*;\r\n\r\npublic class Main\r\n{\r\n    public static String nullreturnfunc()\r\n    {\r\n        return null;\r\n        \r\n    }\r\n    public static void main (String[] args) {\r\n        String test;\r\n        test=nullreturnfunc();\r\n        try \r\n        {\r\n            System.out.println(test.charAt(3));\r\n        } \r\n        catch(Exception e) \r\n        {\r\n            System.out.println(\"The value is null!\");\r\n        }\r\n    }\r\n}\r\n<\/pre>\n<p><strong>Output:<\/strong><\/p>\n<div class=\"code-output\">The value is null!<\/div>\n<h3>Best Ways to Use Null<\/h3>\n<div>\n<p>The following are recommended practices to bear in mind when utilizing null in Java:<\/p>\n<ul>\n<li><strong>Beware of null references:<\/strong> Before using a reference variable, always take into account the possibility that it might be null.<\/li>\n<li><strong>Make strategic use of null checks:<\/strong> Only when required, add null checks to avoid NullPointerExceptions.<\/li>\n<li><strong>Examine alternatives to null:<\/strong> You may be able to completely avoid null references by redesigning your program in certain situations.<\/li>\n<li><strong>Null usage of documents:<\/strong> If you choose to use null, be sure to explain its purpose and methodology in order to make the code easier to read.<\/li>\n<\/ul>\n<\/div>\n<h3>Summary<\/h3>\n<p>We learned a lot about null in Java. It is essential to have a good grasp of null in Java.<\/p>\n<p>Even experienced Java programmers sometimes run into fatal NullPointerExceptions and have no idea how to fix the bug.<\/p>\n<p>Hence, a clear understanding of Java Null will come in handy.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Before we talk about null in Java, let us go back a few steps and recall what variables in Java are. Well, simply speaking, they can be thought of as tumblers. And the value&#46;&#46;&#46;<\/p>\n","protected":false},"author":5,"featured_media":84888,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[32],"tags":[128,18534,6833,7610,23629,9145,11462,13793,15001,15080],"class_list":["post-12398","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java","tag-and","tag-facts-about-java-null","tag-instanceof-operator","tag-java-null","tag-java-null-pointer-exception","tag-null-is-case-sensitive","tag-reference-variable-value","tag-static-vs-non-static-methods","tag-type-of-null","tag-types-of-nulls-in-java"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Java Null - 7 Unknown Facts about Null in Java - DataFlair<\/title>\n<meta name=\"description\" content=\"Explore Java Null Tutorial &amp; Interesting facts about Null: Case sensitivity, Reference Variable Value, Autoboxing &amp; 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