Avoiding != null statements

java null check best practice
java 8 null check best practice
java check parameter not null
java check if object is null or empty
java null conditional operator
how to avoid null pointer exception in java 8
string null check in java 8
how to check all properties of an object whether null or empty java

I use object != null a lot to avoid NullPointerException.

Is there a good alternative to this?

For example:

if (someobject != null) {
    someobject.doCalc();
}

This avoids a NullPointerException, when it is unknown if the object is null or not.

Note that the accepted answer may be out of date, see https://stackoverflow.com/a/2386013/12943 for a more recent approach.

Java 8 has introduced a new class Optional in java.util package.

Advantages of Java 8 Optional:

1.) Null checks are not required. 2.) No more NullPointerException at run-time. 3.) We can develop clean and neat APIs.

Optional - A container object which may or may not contain a non-null value. If a value is present, isPresent() will return true and get() will return the value.

For more details find here oracle docs :- https://docs.oracle.com/javase/8/docs/api/java/util/Optional.html

Avoid Check for Null Statement in Java, Learn several strategies for avoiding the all-too-familiar boilerplate Avoid Check for Null Statement in Java if (result != null && result. Although we eliminated the need for a null check on the caller of this API, we used it to return an empty response. To avoid this, Optional provides an ofNullable method that returns an Optional with the specified value, or empty, if the value is null:

You can use FindBugs. They also have an Eclipse plugin) that helps you find duplicate null checks (among other things), but keep in mind that sometimes you should opt for defensive programming. There is also Contracts for Java which may be helpful.

How to avoid != null statements?, I use code object != null to avoid NullPointerException . Is there a good alternative to solve this as follow ? if (someobject != null) { someobject. C# - the null-conditional Operator and the road to avoid nested if statements 28 May 2016 on c#, .net, operator, c#6. You probably ended up here because you want to avoid nested if statements or found a ? symbol in a codebase, that you did not understand. Perhaps you are just looking for an easy way to do null checks.

All in all to avoid statement

if (object != null) {
    ....
}
  1. since java 7 you can use Objects methods:

    Objects.isNull(object)

    Objects.nonNull(object)

    Objects.requireNonNull(object)

    Objects.equals(object1, object2)

  2. since java 8 you can use Optional class (when to use)

object.ifPresent(obj -> ...); java 8

object.ifPresentOrElse(obj -> ..., () -> ...); java 9

  1. rely on method contract (JSR 305) and use Find Bugs. Mark your code with annotations @javax.annotation.Nullable and @javax.annotation.Nonnnul. Also Preconditions are available.

    Preconditions.checkNotNull(object);

  2. In special cases (for example for Strings and Collections) you can use apache-commons (or Google guava) utility methods:

public static boolean isEmpty(CharSequence cs) //apache CollectionUtils

public static boolean isEmpty(Collection coll) //apache StringUtils

public static boolean isEmpty(Map map) //apache MapUtils

public static boolean isNullOrEmpty(@Nullable String string) //Guava Strings

  1. When you need to assign default value when null use apache commons lang

public static Object defaultIfNull(Object object, Object defaultValue)

Avoiding Null Checks in Java 8, This post describes techniques how to prevent null checks and Outer outer = new Outer(); if (outer != null && outer.nested != null  As we know int is a primitive data type and cannot be null. In my program i want to do a condition check like int i != "" but it says operator != cannot be applied to int,null. Any solution? EDI

Since Java 7 the class java.util.Objects exists.

But since Java 8, you can use Objects.isNull(var) and Objects.nonNull(var) methods of Objects class to do the null pointer check.

For example,

String var1 = null;
Date var2 = null;
Long var3 = null;

if(Objects.isNull(var1) && Objects.isNull(var2) && Objects.isNull(var3))
    System.out.println("All Null");
else if (Objects.nonNull(var1) && Objects.nonNull(var2) && Objects.nonNull(var3))
    System.out.println("All Not Null");

Avoiding != null statements, I use object != null a lot to avoid NullPointerException. Is there a good alternative to this? For example: if (someobject != null) {. someobject. If statement not equal to. Ask Question in order to avoid a NullPointerException Avoiding != null statements. 1722.

I follow below guidelines to avoid null checks.

  1. Avoid lazy initialization of member variables as much as possible. Initialize the variables in declaration itself. This will handle NullPointerExceptions.

  2. Decide on mutability of member variables early in the cycle. Use language constructs like final keyword effectively.

  3. If you know that augments for method won't be changed, declare them as final.

  4. Limit the mutation of data as much as possible. Some variables can be created in a constructor and can never be changed. Remove public setter methods unless they are really required.

    E.g. Assume that one class in your application (A.java) is maintaining a collection like HashMap. Don't provide public getter method in A.java and allow B.java to directly add an element in Map. Instead provide an API in A.java, which adds an element into collection.

    // Avoid
    a.getMap().put(key,value)
    
    //recommended
    
    public void addElement(Object key, Object value){
           // Have null checks for both key and value here : single place
           map.put(key,value);
    }
    
  5. And finally, use try{} catch{} finally{} blocks at right places effectively.

How to avoid “!= null” statements in Java?, !=null conditions making it unreadable and ugly. Often times a method needs to return a value or nothing depending on its internal and working  NULL and UNKNOWN are treated the same. If an operand is NULL, the result is NULL unless the operation result is already dictated by the other parameter. The evaluation of the individual clauses in a statement that includes the AND or OR logical operators is stopped as soon as the overall statement can be resolved.

Avoiding != null statements, I use object != null a lot to avoid NullPointerException. Is there a good alternative to this? For example: if (someobject != null) { someobject. Not Equal is an operator in VBA which can also be termed as a negation operator, it is a logical function so the output returned by this function is either true or false, we know that equal operator is “=” this but not equal is “<>” in VBA so whatever the value we get from the equal operator we will get exact opposite value using Not

Better null-checking in Java, if (pathsStr != null) { ObjectMapper objectMapper = new ObjectMapper(); try { String[] paths = objectMapper.readValue(pathsStr, String[].class);. The standard equality operators ( == and !=) use the Abstract Equality Comparison Algorithm to compare two operands. If the operands are of different types, it will attempt to convert them to the same type before making the comparison, e.g., in the expression 5 == '5', the string on the right is converted to Number before the comparison is made.

10 Tips to Handle Null Effectively, if (myVariable != null) // good Therefore, we should avoid returning null or complicating things with Optional With the index in hand, we can create the requisite PreparedStatement required to execute the SQL statement  IF Statements The IF statement allows you to implement conditional branching logic in your programs. With it, you’ll be able to implement requirements such as: If the salary is between … - Selection from Oracle PL/SQL Programming, 5th Edition [Book]

Comments
  • @Shervin Encouraging nulls makes the code less understandable and less reliable.
  • The Elvis operators were proposed but it looks like it won't be in Java 7. Too bad, ?. ?: and ?[] are incredible time savers.
  • Not using null is superior to most other suggestions here. Throw exceptions, don't return or allow nulls. BTW - 'assert' keyword is useless, because it's disabled by default. Use an always-enabled failure mechanism
  • This is one reason why I am now using Scala. In Scala everything is not nullable. If you want to allow to pass or return "nothing", then you have to exlicitly use Option[T] instead of just T als argument or return type.
  • @thSoft Indeed, Scala's awesome Option type is marred by the language's unwillingness to control or disallow null. I mentioned this on hackernews and got downvoted and told that "nobody uses null in Scala anyway". Guess what, I'm already finding nulls in coworker-written Scala. Yes, they are "doing it wrong" and must be educated about it, but the fact remains the language's type system should protect me from this and it doesn't :(
  • explain very well
  • If you're constantly going to negate the return value, wouldn't it be better to simply write a function isNotNull? Doesn't that more clearly indicate your intent?
  • @TMN: your are right, ideally I'd like to have both a isNull and isNotNull method.
  • I fail to see how this is more concise than "someobject != null".
  • Compile-time and run-time dev tools like findbugs will have a harder time identifying duplicate null checks. Also, you better hope Java inlines that isNull function,
  • you can see there are a lot of answers with many upvotes, what is special about your answer?
  • I just wanted to add a few more functions made available with Java 9.
  • then emphasize on it with a bold font at the beginning of your post
  • are you proposing intercept each method of entire app?