{"id":8017,"date":"2022-12-06T23:28:33","date_gmt":"2022-12-07T04:28:33","guid":{"rendered":"https:\/\/springframework.guru\/?p=8017"},"modified":"2024-10-20T08:23:36","modified_gmt":"2024-10-20T12:23:36","slug":"how-to-use-the-java-optional","status":"publish","type":"post","link":"https:\/\/springframework.guru\/how-to-use-the-java-optional\/","title":{"rendered":"How to Use the Java Optional Properly"},"content":{"rendered":"

One of the exceptions that every Java Programmer must have faced is NullPointerException<\/a>. They are hard to debug and cause unexpected termination of your application. To better handle NullPointerException<\/code>, Java 8 has introduced the Optional class.
\nIn this post, I\u2019ll explain how to use Optional<\/code> in Java applications.<\/p>\n

Optional Overview<\/h2>\n

The main benefit of the Optional<\/code> class is that it prevents unwanted NullPointerExceptions<\/code>.<\/p>\n

Consider this code.<\/p>\n

NPEExample.java<\/strong><\/p>\n

package guru.springframework.optionaldemos;\n\npublic class NPEExample {\n\n    static String convert(String[] strArr, int index){\n        if(strArr[index]!=null)\n           return strArr[index].toUpperCase();\n        else\n            return \"Please provide valid input\";\n    }\n    public static void main(String[] args) {\n        String[] strArr= new String[5];\n        String convertedValue= convert(strArr,3);\n        System.out.println(convertedValue);\n    }\n}<\/pre>\n
When you run the preceding code, you get NullPointerException<\/code>, like this.<\/p>\n
\"\"<\/a><\/p>\n
To prevent this, we can do explicit null checks, like this.
\n NPEExample.java<\/strong><\/p>\n
package guru.springframework.optionaldemos;\n\npublic class NPEExample {\n\n    static String convert(String[] strArr, int index){\n        if(strArr[index]!=null)\n           return strArr[index].toUpperCase();\n        else\n            return \"Please provide valid input\";\n    }\n    public static void main(String[] args) {\n        String[] strArr= new String[5];\n        String convertedValue= convert(strArr,3);\n        System.out.println(convertedValue);\n    }\n}\n<\/pre>\n
With Optional<\/code>, the code will now look like this.<\/p>\n
String res;\nString[] strArr= new String[6];\nOptional<String> checkNull = Optional.ofNullable(strArr[5]);\nif (checkNull.isPresent()) {\n    res = convert(strArr, 5);\n    System.out.println(res);\n}\nelse\nSystem.out.println(\"Value is not present\");\n<\/pre>\n
In the preceding code, the ofNullable()<\/code> method returns an Optional<\/code> describing the given value, if non-null. Otherwise, this method returns an empty Optional<\/code>. In the preceding code the method returns an empty Optional<\/code>.<\/p>\n
The isPresent()<\/code> method returns true<\/code> if a value is present. Otherwise, it returns false<\/code>. In the preceding code, the isPresent()<\/code> method will return false<\/code>, and the program will output Value is not present<\/code>.<\/p>\n
Creating Optional Objects<\/h2>\n
The Optional<\/code> class comes with a number of static methods to create Optional<\/code> objects. The methods are:<\/p>\n