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Java Tips Too Best Practices To Avoid Nullpointerexception Inward Coffee Applications

A NullPointerException inward Java application is best agency to solve it together with that is also key to write robust programs which tin travel smoothly. As it said “prevention is meliorate than cure”, same is truthful amongst nasty NullPointerException. Thankfully past times applying closed to defensive coding techniques together with next contract betwixt multiple purpose of application, you lot tin avoid NullPointerException inward Java to a practiced extent. By the agency this is the instant postal service on NullPointerException inward , In concluding postal service nosotros lead maintain discussed almost common displace of NullPointerException inward Java together with inward this tutorial,  we volition acquire closed to Java coding techniques together with best practices, which tin last used to avoid NullPointerException inward Java. Following these Java tips also minimize release of !=null check, which litter lot of Java code. As an sense Java programmer, you lot may last aware of closed to of these techniques together with already next it inward your project, but for freshers together with intermediate developers, this tin last practiced learning. By the way, if you lot know whatever other Java tips to avoid NullPointerException together with cut null checks inward Java, hence delight portion amongst us.

Java Tips together with Best practices to avoid NullPointerException 

These are elementary techniques, which is rattling slowly to follow, but has important touching on on code character together with robustness. In my experience, but offset tip is resulted inward important improvement inward code quality. As I said earlier, if you lot know whatever other Java tips or best practice, which tin assist to cut null check, hence you lot tin portion amongst us past times commenting on this article.

1) Call equals() together with equalsIgnoreCase() method on known String literal rather unknown object

Always telephone telephone equals() method on known String which is non null. Since equals() method is symmetric, calling a.equals(b) is same equally calling b.equals(a), together with that’s why many programmer don’t pay attending on object a together with b. One side outcome of this telephone telephone tin outcome inward NullPointerException, if caller is null.

Object unknownObject = null;

//wrong agency - may displace NullPointerException

if(unknownObject.equals("knownObject")){

   System.err.println("This may outcome inward NullPointerException if unknownObject is null");

}

//right agency - avoid NullPointerException fifty-fifty if unknownObject is null

if("knownObject".equals(unknownObject)){

    System.err.println("better coding avoided NullPointerException");

}

This is the most slowly Java tip or best exercise to avoid NullPointerException, but results inward tremendous improvement, because of equals()being a mutual method.

2) Prefer valueOf() over toString() where both render same result

Since calling toString() on null object throws NullPointerException, if nosotros tin acquire same value past times calling valueOf() hence prefer that, equally passing null to  valueOf() returns "null", particularly inward instance of wrapper classes  like Integer, Float, Double or BigDecimal.

BigDecimal bd = getPrice();

System.out.println(String.valueOf(bd)); //doesn’t throw NPE

System.out.println(bd.toString()); //throws "Exception inward thread "main" java.lang.NullPointerException"

Follow this Java tips, if you lot are unsure almost object beingness null or not.

3) Using null rubber methods together with libraries

There are lot of opened upwards rootage library out there, which does the heavy lifting of checking null for you. One of the most mutual i is StringUtils from Apache commons. You tin occupation StringUtils.isBlank(), isNumeric(), isWhiteSpace() together with other utility methods without worrying of  NullPointerException.

//StringUtils methods are null safe, they don't throw NullPointerException

System.out.println(StringUtils.isEmpty(null));

System.out.println(StringUtils.isBlank(null));

System.out.println(StringUtils.isNumeric(null));

System.out.println(StringUtils.isAllUpperCase(null));

Output:

true

true

false

false

But before reaching to whatever conclusion don't forget to read the documentation of Null rubber methods together with classes. This is closed to other Java best practices, which doesn't require much effort, but outcome inward slap-up improvements.

4) Avoid returning null from method, instead render empty collection or empty array.

This Java best exercise or tips is also mentioned past times Joshua Bloch inward his book Effective Java which is closed to other practiced rootage of meliorate programming inward Java. By returning empty collection or empty array you lot brand certain that basic calls similar size(), length() doesn't neglect amongst NullPointerException. Collections course of pedagogy provides convenient empty List, Set together with Map equally Collections.EMPTY_LIST, Collections.EMPTY_SET together with Collections.EMPTY_MAP which tin last used accordingly. Here is code example

public List getOrders(Customer customer){

   List outcome = Collections.EMPTY_LIST;

   return result;

}

Similarly you lot tin occupation Collections.EMPTY_SET together with Collections.EMPTY_MAP instead of returning null.

5)  Use of annotation @NotNull together with @Nullable

While writing method you lot tin define contracts almost nullability, past times declaring whether a method is null rubber or not, past times using annotations similar @NotNull together with @Nullable. Modern days compiler, IDE or tool tin read this annotation together with assist you lot to seat a missing null check, or may inform you lot almost an unnecessary null check, which is cluttering your code. IntelliJ IDE together with findbugs already supports such annotation. These annotations are also purpose of JSR 305, but fifty-fifty inward the absence of whatever tool or IDE support, this  annotation itself travel equally documentation. By looking @NotNull together with @Nullable, programmer tin himself make upwards one's hear whether to banking concern check for null or not. By the agency ,this is relatively novel best exercise for Java programmers together with it volition convey closed to fourth dimension to acquire adopted.

6)  Avoid unnecessary autoboxing together with unboxing inward your code

Despite of other disadvantages similar creating temporary object, autoboxing are also prone to NullPointerException, if the wrapper course of pedagogy object is null. For example,  following code volition neglect amongst NullPointerException if individual doesn't lead maintain telephone release together with instead render null.

Person ram = new Person("ram");

int telephone = ram.getPhone();

Not but equality but < , > tin also throw NullPointerException if used along autoboxing together with unboxing. See this article to acquire more pitfalls of autoboxing together with unboxing inward Java.

7) Follow Contract together with define reasonable default value

One of the best agency to avoid NullPointerException inward Java is equally elementary equally defining contracts together with next them. Most of the NullPointerException occurs because Object is created amongst incomplete information or all required dependency is non provided. If you lot don't allow to make incomplete object together with gracefully deny whatever such asking you lot tin forbid lots of NullPointerException downwardly the road. Similarly if  Object is allowed to last created, than you lot should travel amongst reasonable default value. for instance an Employee object tin non last created without id together with name, but tin lead maintain an optional telephone number. Now if Employee doesn't lead maintain telephone release than instead of returning null, render default value e.g. zero, but that alternative has to last carefully taken sometime checking for null is slowly rather than calling an invalid number. One same note, past times defining what tin last null together with what tin non last null, caller tin brand an informed decision. Choice of failing fast or accepting null is also an of import pattern determination you lot bespeak to convey together with adhere consistently.

8)  If you lot are using database for storing your domain object such equally Customers, Orders etc than you lot should define your null-ability constraints on database itself. Since database tin acquire information from multiple sources, having null-ability banking concern check inward DB volition ensure information integrity. Maintaining null constraints on database volition also assist inward reducing null banking concern check inward Java code. While loading objects from database you lot volition last sure, which plain tin last null together with which plain is non null, this volition minimize unnecessary != null banking concern check inward code.

9) Use Null Object Pattern

This is closed to other agency of avoiding NullPointerExcpetion inward Java. If a method returns an object, on which caller, perform closed to operations e.g. Collection.iterator() method returns Iterator, on which caller performs traversal. Suppose if a caller doesn’t lead maintain whatever Iterator, it tin render Null object instead of null. Null object is a particular object, which has dissimilar important inward dissimilar context, for example, hither an empty Iterator, calling hasNext() on which returns false, tin last a null object. Similarly inward instance of method, which returns Container or Collection types, empty object should last used instead of returning null. I am planning to write a split upwards article on Null Object pattern, where I volition portion few to a greater extent than examples of NULL objects inward Java.

That’s all guys, these are distich of slowly to follow Java tips together with best practices to avoid NullPointerException. You would appreciate, how useful these tips tin be, without also much of effort. If you lot are using whatever other tip to avoid this exception, which is non included inward this list, than delight portion amongst us via comment, together with I volition include them here.

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