Java Tips In Addition To Best Practices To Avoid Nullpointerexception Inwards Coffee Applications

A NullPointerException inwards Java application is best agency to solve it as well as that is also key to write robust programs which tin move move smoothly. As it said “prevention is amend than cure”, same is truthful amongst nasty NullPointerException. Thankfully yesteryear applying only about defensive coding techniques as well as next contract betwixt multiple business office of application, you lot tin move avoid NullPointerException inwards Java to a expert extent. By the agency this is the minute post service on NullPointerException inwards , In final post service nosotros receive got discussed almost common drive of NullPointerException inwards Java as well as inwards this tutorial,  we volition acquire only about Java coding techniques as well as best practices, which tin move hold out used to avoid NullPointerException inwards Java. Following these Java tips also minimize position out of !=null check, which litter lot of Java code. As an sense Java programmer, you lot may hold out aware of only about of these techniques as well as already next it inwards your project, but for freshers as well as intermediate developers, this tin move hold out expert learning. By the way, if you lot know whatever other Java tips to avoid NullPointerException as well as trim naught checks inwards Java, as well as then delight part amongst us.

Java Tips as well as Best practices to avoid NullPointerException 

These are unproblematic techniques, which is really slow to follow, but has important touching on on code lineament as well as robustness. In my experience, only start tip is resulted inwards important improvement inwards code quality. As I said earlier, if you lot know whatever other Java tips or best practice, which tin move assist to trim naught check, as well as then you lot tin move part amongst us yesteryear commenting on this article.

1) Call equals() as well as 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), as well as that’s why many programmer don’t pay attending on object a as well as b. One side lawsuit of this telephone telephone tin move resultant inwards NullPointerException, if caller is null.

Object unknownObject = null;

//wrong agency - may drive NullPointerException

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

   System.err.println("This may resultant inwards 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 slow Java tip or best practise to avoid NullPointerException, but results inwards tremendous improvement, because of equals()being a mutual method.

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

Since calling toString() on naught object throws NullPointerException, if nosotros tin move acquire same value yesteryear calling valueOf() as well as then prefer that, equally passing naught to  valueOf() returns "null", especially inwards 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 inwards thread "main" java.lang.NullPointerException"

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

3) Using naught prophylactic methods as well as libraries

There are lot of opened upwards rootage library out there, which does the heavy lifting of checking naught for you. One of the most mutual 1 is StringUtils from Apache commons. You tin move purpose StringUtils.isBlank(), isNumeric(), isWhiteSpace() as well as other utility methods without worrying of  NullPointerException.

//StringUtils methods are naught 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 prophylactic methods as well as classes. This is only about other Java best practices, which doesn't require much effort, but resultant inwards swell improvements.

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

This Java best practise or tips is also mentioned yesteryear Joshua Bloch inwards his book Effective Java which is only about other expert rootage of amend programming inwards Java. By returning empty collection or empty array you lot brand certain that basic calls similar size(), length() doesn't neglect amongst NullPointerException. Collections shape provides convenient empty List, Set as well as Map equally Collections.EMPTY_LIST, Collections.EMPTY_SET as well as Collections.EMPTY_MAP which tin move hold out used accordingly. Here is code example

public List getOrders(Customer customer){

   List resultant = Collections.EMPTY_LIST;

   return result;

}

Similarly you lot tin move purpose Collections.EMPTY_SET as well as Collections.EMPTY_MAP instead of returning null.

5)  Use of annotation @NotNull as well as @Nullable

While writing method you lot tin move define contracts almost nullability, yesteryear declaring whether a method is naught prophylactic or not, yesteryear using annotations similar @NotNull as well as @Nullable. Modern days compiler, IDE or tool tin move read this annotation as well as assist you lot to position a missing naught check, or may inform you lot almost an unnecessary naught check, which is cluttering your code. IntelliJ IDE as well as findbugs already supports such annotation. These annotations are also business office of JSR 305, but fifty-fifty inwards the absence of whatever tool or IDE support, this  annotation itself move equally documentation. By looking @NotNull as well as @Nullable, programmer tin move himself determine whether to depository fiscal establishment check for naught or not. By the agency ,this is relatively novel best practise for Java programmers as well as it volition convey only about fourth dimension to acquire adopted.

6)  Avoid unnecessary autoboxing as well as unboxing inwards your code

Despite of other disadvantages similar creating temporary object, autoboxing are also prone to NullPointerException, if the wrapper shape object is null. For example,  following code volition neglect amongst NullPointerException if mortal doesn't receive got telephone position out as well as instead render null.

Person ram = new Person("ram");

int telephone = ram.getPhone();

Not only equality but < , > tin move also throw NullPointerException if used along autoboxing as well as unboxing. See this article to acquire more pitfalls of autoboxing as well as unboxing inwards Java.

7) Follow Contract as well as define reasonable default value

One of the best agency to avoid NullPointerException inwards Java is equally unproblematic equally defining contracts as well as 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 do incomplete object as well as gracefully deny whatever such asking you lot tin move preclude lots of NullPointerException downwards the road. Similarly if  Object is allowed to hold out created, than you lot should move amongst reasonable default value. for instance an Employee object tin move non hold out created without id as well as name, but tin move receive got an optional telephone number. Now if Employee doesn't receive got telephone position out than instead of returning null, render default value e.g. zero, but that selection has to hold out carefully taken sometime checking for naught is slow rather than calling an invalid number. One same note, yesteryear defining what tin move hold out naught as well as what tin move non hold out null, caller tin move brand an informed decision. Choice of failing fast or accepting naught is also an of import pattern determination you lot request to convey as well as 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 move acquire information from multiple sources, having null-ability depository fiscal establishment check inwards DB volition ensure information integrity. Maintaining naught constraints on database volition also assist inwards reducing null depository fiscal establishment check inwards Java code. While loading objects from database you lot volition hold out sure, which champaign tin move hold out naught as well as which champaign is non null, this volition minimize unnecessary != null depository fiscal establishment check inwards code.

9) Use Null Object Pattern

This is only about other agency of avoiding NullPointerExcpetion inwards Java. If a method returns an object, on which caller, perform only about operations e.g. Collection.iterator() method returns Iterator, on which caller performs traversal. Suppose if a caller doesn’t receive got whatever Iterator, it tin move render Null object instead of null. Null object is a particular object, which has dissimilar pregnant inwards dissimilar context, for example, hither an empty Iterator, calling hasNext() on which returns false, tin move hold out a naught object. Similarly inwards instance of method, which returns Container or Collection types, empty object should hold out used instead of returning null. I am planning to write a carve upwards article on Null Object pattern, where I volition part few to a greater extent than examples of NULL objects inwards Java.

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

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