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• Elegant check for null and exit in C#

  - by aip.cd.aish

  What is an elegant way of writing this? if (lastSelection != null) { lastSelection.changeColor(); } else { MessageBox.Show("No Selection Made"); return; } changeColor() is a void function and the function that is running the above code is a void function as well.

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• "Cannot read property 'xxx' of null"

  - by Matrym

  I've got a document fragment with children that I want to loop over (when possible). This is causing an error "Cannot read property 'xxx' of null". How do I test if this will be the case?

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• When was the NULL macro not 0?

  - by Jurily

  I vaguely remember reading about this a couple of years ago, but I can't find any reference on the net. Can you give me an example where the NULL macro didn't expand to 0?

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• NetBeans IDE 7.3 Knows Null

  - by Geertjan

  What's the difference between these two methods, "test1" and "test2"? public int test1(String str) {     return str.length(); } public int test2(String str) {     if (str == null) {         System.err.println("Passed null!.");         //forgotten return;     }     return str.length(); } The difference, or at least, the difference that is relevant for this blog entry, is that whoever wrote "test2" apparently thinks that the variable "str" may be null, though did not provide a null check. In NetBeans IDE 7.3, you see this hint for "test2", but no hint for "test1", since in that case we don't know anything about the developer's intention for the variable and providing a hint in that case would flood the source code with too many false positives:  Annotations are supported in understanding how a piece of code is intended to be used. If method return types use @Nullable, @NullAllowed, @CheckForNull, the value is considered to be "strongly possible to be null", as well as if the variable is tested to be null, as shown above. When using @NotNull, @NonNull, @Nonnull, the value is considered to be non-null. (The exact FQNs of the annotations are ignored, only simple names are checked.) Here are examples showing where the hints are displayed for the non-null hints (the "strongly possible to be null" hints are not shown below, though you can see one of them in the screenshot above), together with a comment showing what is shown when you hover over the hint: There isn't a "one size fits all" refactoring for these various instances relating to null checks, hence you can't do an automated refactoring across your code base via tools in NetBeans IDE, as shown yesterday for class member reordering across code bases. However, you can, instead, go to Source | Inspect and then do a scan throughout a scope (e.g., current file/package/project or combinations of these or all open projects) for class elements that the IDE identifies as potentially having a problem in this area: Thanks to Jan Lahoda, who reports that this currently also works in NetBeans IDE 7.3 dev builds for fields but that may need to be disabled since right now too many false positives are returned, for help with the info above and any misunderstandings are my own fault!

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• WHERE x = @x OR @x IS NULL

  - by steveh99999

  Every SQL DBA and developer should read the blog of MVP Erland Sommarskog – but particularly  his article on dynamic search conditions in T-SQL. I’ve linked above to his SQL 2005 article but his 2008 version is also a must-read. I seem to regularly come across uses of the SQL in the title above… Erland’s article explains in detail why this is inefficient, but I came across a nice example recently… A stored procedure contained the following code :- WHERE @Name is null or [Name] like @Name as a nonclustered index exists on the Name column, you might assume this would be handled efficiently by SQL Server. However, I got the following output from SET STATISTICS IO Table 'xxxxx'. Scan count 15, logical reads 47760, physical reads 9, read-ahead reads 13872, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. Note the high number of logical reads… After a bit of investigation, we found that @Name could never actually be set to NULL in this particular example. ie the @x IS NULL was spurious… So, we changed the call to WHERE  [Name] like @Name Now, how much more efficient is this code ? Table 'xxxxx'. Scan count 3, logical reads 24, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0 A nice easy win in this case…… a full index scan has been replaced by a significantly more efficient index seek. I managed to recreate the same behaviour on Adventureworks – here’s a quick query to demonstrate :- USE adventureworks SET STATISTICS IO ON DECLARE @id INT = 51721 SELECT * FROM Sales.SalesOrderDetail WHERE @id IS NULL OR salesorderid = @id SELECT * FROM Sales.SalesOrderDetail WHERE salesorderid = @id Take a look at the STATISTICS IO output and compare the actual query plans used to prove the impact of  WHERE @id IS NULL. And just to follow some of Erland’s advice – here’s how you could get similar performance if it was possible that @id could actually sometimes contain NULL. DECLARE @sql NVARCHAR(4000), @parameterlist NVARCHAR(4000) DECLARE @id INT = 51721 – or change to NULL to prove query is functionally correct SET @sql = 'SELECT * FROM Sales.SalesOrderDetail WHERE 1 = 1' IF @id IS NOT NULL SET @sql = @sql + ' AND salesorderid = @id' IF @id IS NULL SET @sql = @sql + ' AND salesorderid IS NULL' SET @parameterlist = '@id INT' EXEC sp_executesql @sql, @parameterlist,@id Sometimes I think we focus too much on hardware and SQL Server configuration – when really the answer is focus on writing efficient SQL.

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• handle null values for string when implementing IXmlSerializable interface

  - by user208081

  I have the following class that implements IXmlSerializable. When implementing WriteXml(), I need to handle the case where the string members of this class may be null values. What is the best way of handling this? Currently, I am using the default constructor in which all the string properties are initialized to empty string values. This way, when WriteXml() is called, the string will not be null. One other way I could do this is check using String.IsNullOrEmpty before writing each string in xml. Any suggestions on how I can improve this code? using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Xml.Serialization; using System.Globalization; namespace TCS.Common.InformationObjects { public sealed class FaxSender : IXmlSerializable { #region Public Constants private const string DEFAULT_CLASS_NAME = "FaxSender"; #endregion Public Constants #region Public Properties public string Name { get; set; } public string Organization { get; set; } public string PhoneNumber { get; set; } public string FaxNumber { get; set; } public string EmailAddress { get; set; } #endregion Public Properties #region Public Methods #region Constructors public FaxSender() { Name = String.Empty; Organization = String.Empty; PhoneNumber = String.Empty; FaxNumber = String.Empty; EmailAddress = String.Empty; } public FaxSender(string name, string organization, string phoneNumber, string faxNumber, string emailAddress) { Name = name; Organization = organization; PhoneNumber = phoneNumber; FaxNumber = faxNumber; EmailAddress = emailAddress; } #endregion Constructors #region IXmlSerializable Members public System.Xml.Schema.XmlSchema GetSchema() { throw new NotImplementedException(); } public void ReadXml(System.Xml.XmlReader reader) { throw new NotImplementedException(); } public void WriteXml(System.Xml.XmlWriter xmlWriter) { try { // <sender> xmlWriter.WriteStartElement("sender"); // Write the name of the sender as an element. xmlWriter.WriteElementString("name", this.Name.ToString(CultureInfo.CurrentCulture)); // Write the organization of the sender as an element. xmlWriter.WriteElementString("organization", this.Organization.ToString(CultureInfo.CurrentCulture)); // Write the phone number of the sender as an element. xmlWriter.WriteElementString("phone_number", this.PhoneNumber.ToString(CultureInfo.CurrentCulture)); // Write the fax number of the sender as an element. xmlWriter.WriteElementString("fax_number", this.FaxNumber.ToString(CultureInfo.CurrentCulture)); // Write the email address of the sender as an element. xmlWriter.WriteElementString("email_address", this.EmailAddress.ToString(CultureInfo.CurrentCulture)); // </sender> xmlWriter.WriteEndElement(); } catch { // Rethrow any exceptions. throw; } } #endregion IXmlSerializable Members #endregion Public Methods } }

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• jQuery getJson returning null

  - by Adam

  I'm trying to use this api that lets you reference an exact text, but the getJson does not seem to be working, it's just returning null. $.getJSON('http://api.biblia.com/v1/bible/content/KJV.json?key=MYAPIKEY=John+3:16-18&style=bibleTextOnly', function(data) { alert(data); }); I just took the key out, i've been testing it with my real api key, and it works fine when i just visit the url. is there anything else i need to do to make it work? This is what you get from the url when you have an api key in the url: {"text":"For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. For God sent not his Son into the world to condemn the world; but that the world through him might be saved. He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God."}

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• Android 2.1 View's getDrawingCache() method always returns null

  - by Impression

  Hello, I'm working with Android 2.1 and have the following problem: Using the method View.getDrawingCache() always returns null. Example code: public void onCreate(final Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); final View view = findViewById(R.id.ImageView01); view.setDrawingCacheEnabled(true); view.buildDrawingCache(); final Bitmap bmp = view.getDrawingCache(); System.out.println(bmp); } I've already tried different ways to configure the View object for generating the drawing cache (e.g. View.setWillNotDraw(boolean) and View.setWillNotCacheDrawing(boolean)), but nothing works. What is the right ways, or what do I wrong?

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• Null-coalescing operator and operator && in C#

  - by abatishchev

  Is it possible to use together any way operator ?? and operator && in next case: bool? Any { get { var any = this.ViewState["any"] as bool?; return any.HasValue ? any.Value && this.SomeBool : any; } } This means next: if any is null then this.Any.HasValue return false if any has value, then it returns value considering another boolean property, i.e. Any && SomeBool

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• Null Pointer Exception on a 2D array (Java)

  - by user315156

  I have a class, "Tetris", in which one of the instance variables is "board". "board" is 2D array of Color objects. Upon the creation of a tetris object I call a method that sets the dimensions of board and then sets all of the Color objects to be the Default value, that is to say, Color.blue. public Tetris(int rows, int cols){ this.rows = rows; this.cols = cols; reset(rows, cols); } public void reset(int rows, int cols){ Color[][] board = new Color[rows][cols]; for(int i = 0; i Unfortunately, when I run the code (which obviously has not been posted in its entirety) I get a null pointer exception on the line: board[i][j] = DEFAULT_COLOR; // Color.blue; //DEFAULT-COLOR. Is there anything obviously wrong with what I am doing? (Sorry if there are glaring format issues, this is my first time on Stack Overflow)

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• Fluent Nhibernate Automap convention for not-null field

  - by user215015

  Hi, Could some one help, how would I instruct automap to have not-null for a cloumn? public class Paper : Entity { public Paper() { } [DomainSignature] [NotNull, NotEmpty] public virtual string ReferenceNumber { get; set; } [NotNull] public virtual Int32 SessionWeek { get; set; } } But I am getting the following: <column name="SessionWeek"/> I know it can be done using fluent-map. but i would like to know it in auto-mapping way. Many thanks. Regards Robie

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• Changing a SUM returned NULL to zero

  - by Lee_McIntosh

  I have a Stored Procedure as follows: CREATE PROC [dbo].[Incidents] (@SiteName varchar(200)) AS SELECT ( SELECT SUM(i.Logged) FROM tbl_Sites s INNER JOIN tbl_Incidents i ON s.Location = i.Location WHERE s.Sites = @SiteName AND i.[month] = DATEADD(mm, DATEDIFF(mm, 0, GetDate()) -1,0) GROUP BY s.Sites ) AS LoggedIncidents 'tbl_Sites contains a list of reported on sites. 'tbl_Incidents containts a generated list of total incidents by site/date (monthly) 'If a site doesnt have any incidents that month it wont be listed. The problem I'm having is that a site doesnt have any Incidents this month and as such i get a NULL value returned for that site when i run this sproc, but i need to have a zero/0 returned to be used within a chart in SSRS. I've tried the using coalesce and isnull to no avail. SELECT COALESCE(SUM(c.Logged,0)) SELECT SUM(ISNULL(c.Logged,0)) Is there a way to get this formatted correctly? Cheers, Lee

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• django left join with null

  - by SledgehammerPL

  The model: class Product(models.Model): name = models.CharField(max_length = 128) def __unicode__(self): return self.name class Receipt(models.Model): name = models.CharField(max_length=128) components = models.ManyToManyField(Product, through='ReceiptComponent') class Admin: pass def __unicode__(self): return self.name class ReceiptComponent(models.Model): product = models.ForeignKey(Product) receipt = models.ForeignKey(Receipt) quantity = models.FloatField(max_length=9) unit = models.ForeignKey(Unit) def __unicode__(self): return unicode(self.quantity!=0 and self.quantity or '') + ' ' + unicode(self.unit) + ' ' + self.product.genitive The idea: there are a components on stock. I'd like to find out which recipes I can made with components which I have. It's not easy - but possible - I made a SQL view, which gets the solution. But I'm learning python and Django so I'd like to make it Django-style ;D The concept of solution: get the set of recipes which has at last one component: list_of_available_components = ReceiptComponent.objects.filter(product__in=list_of_available_products).distinct() list_of_related_receipts = Receipt.objects.filter(receiptcomponent__in = list_of_available_components).distinct() get recipes (from list_of_related_receipts) which has not at last one component list_of_incomplete_recipes = (SELECT * FROM drinkbook_receiptcomponent LEFT JOIN drinkstore_stock_products USING(product_id) WHERE drinkstore_stock_products.stock_id IS NULL AND receipt_id IN (SELECT receipt_id FROM drinkbook_receiptcomponent JOIN drinkstore_stock_products USING(product_id))) get recipes (from list_of_related_receipts) which are not in "list_of_incomplete_recipes"

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• Using a ControlParameter in FilterParameters when the property is null

  - by end-user

  I have a DataList and FormView; they have separate datasources, though they pull the same info. The FormView's datasource has a FilterExpression to pull whatever's been selected on the DataList. On first load, the SelectedValue of the DataList is null (naturally). I expect the FilterExpression to result in zero rows, but it doesn't. If I set the DefaultValue to 0, it does, but then the parameter never updates when I select something from the DataList. Am I doing it wrong?

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• How to check for undefined or null variable in javascript

  - by Thomas Wanner

  We are frequently using the following code pattern in our javascript code if(typeof(some_variable) != 'undefined' && some_variable != null) { // do something with some_variable } and I'm wondering whether there is a less verbose way of checking that has the same effect. According to some forums and literature saying simply if(some_variable) { // do something with some_variable } should have the same effect. Unfortunately, Firebug evaluates such a statement as error on runtime when some_variable is undefined, whereas the first one is just fine for him. Is this only an (unwanted) behavior of Firebug or is there really some difference between those two ways ?

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• Value cannot be null in sportstore exampe

  - by Naim

  Hi everyone, I am having this problem when I want to implement IoC for sportstore example. The code public WindsorControllerFactory(){ container = new WindsorContainer( new XmlInterpreter(new ConfigResource("castle")) ); var controllerTypes= from t in Assembly.GetExecutingAssembly().GetTypes() where typeof(IController).IsAssignableFrom(t) select t; foreach (Type t in controllerTypes) container.AddComponentLifeStyle(t.FullName, t, LifestyleType.Transient); } protected override IController GetControllerInstance(Type controllerType) { return (IController)container.Resolve(controllerType); } } The error said that the value cannot be null in the GetControllerInstance Any help will be appreciated ! Thanks! Naim

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• EXCEL import to sql returning NULL for decimals when in VARCHAR data type

  - by Daniel

  Hi, I am working on a peice of software which has expodentially grown over the last few years and the database needs to be regularly updated. Customers are providing us with data now on large spreadsheets which we format and will start importing into the database. I am using the Import and Export Data (32-bit) Wizard. One column in the database contains values like '1.1.1.2' etc and i am importing them in as a Varchar as that is the data type in the database. However, for values like '8.5', 'NULL' is getting imported insead. It only occurs when there is one decimal point. Is this a formatting error with excel or is it the wrong datatype?

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• NULL pointer dereference in C

  - by user554125

  hey ive got this piece of code. It dereferences a null pointer here. But then there is an and with unsigned int. I really dont understand the whole part. Can someone explain the output.?? struct hi { long a; int b; long c; }; int main() { struct hi ob={3,4,5}; struct hi *ptr=&ob; int num= (unsigned int) & (((struct hi *)0)->b); printf("%d",num); printf("%d",*(int *)((char *)ptr + (unsigned int) & (((struct hi *)0)->b))); } The o/p i get is 44 .But how does it work?

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• Casting an object which could be null

  - by DeeMac

  DateTime? testDate = (DateTime?)arrayOfObjects[dateObject]; Does that code look ok? I attempted to use the as operator but I got the 'non-nullable' error. What I'm trying to say is that the object I'm choosing from the array is either DateTime or a null DateTime but either can be assigned to testDate. Doesn't feel right doing it this way, I think I'm missing something obvious. EDIT: I suppose it's the same as the way I could've adapted the as in the following way: DateTime? testDate = arrayOfObjects[dateObject] as DateTime?; Is either line of code the best way of handling potential nulls?

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• Return Empty String as NULL

  - by Daniel

  I have a listbox select and I want when the user selects null for the empty string it produces to pull the nulls from the SQL table. Here's what I have now. Blank strings return nothing because there are no empty fields in the table. SELECT * FROM dbo.Table WHERE ID = " & TextBox2.Text & " and And Field1 IN (" & Msg1 & ") How do I code that?

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• Comparing two date ranges within the same table

  - by Danny Herran

  I have a table with sales per store as follows: SQL> select * from sales; ID ID_STORE DATE TOTAL ---------- -------- ---------- -------------------------------------------------- 1 1 2010-01-01 500.00 2 1 2010-01-02 185.00 3 1 2010-01-03 135.00 4 1 2009-01-01 165.00 5 1 2009-01-02 175.00 6 5 2010-01-01 130.00 7 5 2010-01-02 135.00 8 5 2010-01-03 130.00 9 6 2010-01-01 100.00 10 6 2010-01-02 12.00 11 6 2010-01-03 85.00 12 6 2009-01-01 135.00 13 6 2009-01-02 400.00 14 6 2009-01-07 21.00 15 6 2009-01-08 45.00 16 8 2009-01-09 123.00 17 8 2009-01-10 581.00 17 rows selected. What I need to do is to compare two date ranges within that table. Lets say I need to know the differences in sales between 01 Jan 2009 to 10 Jan 2009 AGAINST 01 Jan 2010 to 10 Jan 2010. I'd like to build a query that returns something like this: ID_STORE_A DATE_A TOTAL_A ID_STORE_B DATE_B TOTAL_B ---------- ---------- --------- ---------- ---------- ------------------- 1 2010-01-01 500.00 1 2009-01-01 165.00 1 2010-01-02 185.00 1 2009-01-02 175.00 1 2010-01-03 135.00 1 NULL NULL 5 2010-01-01 130.00 5 NULL NULL 5 2010-01-02 135.00 5 NULL NULL 5 2010-01-03 130.00 5 NULL NULL 6 2010-01-01 100.00 6 2009-01-01 135.00 6 2010-01-02 12.00 6 2009-01-02 400.00 6 2010-01-03 85.00 6 NULL NULL 6 NULL NULL 6 2009-01-07 21.00 6 NULL NULL 6 2009-01-08 45.00 6 NULL NULL 8 2009-01-09 123.00 6 NULL NULL 8 2009-01-10 581.00 So, even if there are no sales in one range or another, it should just fill the empty space with NULL. So far, I've come up with this quick query, but I the "dates" from sales to sales2 sometimes are different in each row: SELECT sales.*, sales2.* FROM sales LEFT JOIN sales AS sales2 ON (sales.id_store=sales2.id_store) WHERE sales.date >= '2010-01-01' AND sales.date <= '2010-01-10' AND sales2.date >= '2009-01-01' AND sales2.date <= '2009-01-10' ORDER BY sales.id_store ASC, sales.date ASC, sales2.date ASC What am I missing?

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• Calling a method on an unitialized object (null pointer)

  - by Florin

  What is the normal behavior in Objective-C if you call a method on an object (pointer) that is nil (maybe because someone forgot to initialize it)? Shouldn't it generate some kind of an error (segmentation fault, null pointer exception...)? If this is normal behavior, is there a way of changing this behavior (by configuring the compiler) so that the program raises some kind of error / exception at runtime? To make it more clear what I am talking about, here's an example. Having this class: @interface Person : NSObject { NSString *name; } @property (nonatomic, retain) NSString *name; - (void)sayHi; @end with this implementation: @implementation Person @synthesize name; - (void)dealloc { [name release]; [super dealloc]; } - (void)sayHi { NSLog(@"Hello"); NSLog(@"My name is %@.", name); } @end Somewhere in the program I do this: Person *person = nil; //person = [[Person alloc] init]; // let's say I comment this line person.name = @"Mike"; // shouldn't I get an error here? [person sayHi]; // and here [person release]; // and here

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• Passing NULL value

  - by FFXIII

  Hi. I use an instance of NSXMLParser. I store found chars in NSMutableStrings that are stored in an NSMutableDictionary and these Dicts are then added to an NSMutableArray. When I test this everything seems normal: I count 1 array, x dictionnaries and x strings. In a detailview controller file I want to show my parsed results. I call the class where everthing is stored but I get (null) returned. This is what I do (wrong): XMLParser.h @interface XMLParser : NSObject { NSMutableArray *array; NSMUtableDictionary *dictionary; NSSMutabletring *element; } @property (nonatomic, retain) NSMutableArray *array; @property (nonatomic, retain) NSMutableDictionary *dictionary; @property (nonatomic, retain) NSMutableString *element; XMLParser.m @synthesize array, dictionary, element; //parsing goes on here & works fine //so 'element' is filled with content and stored in a dict in an array //and released at the end of the file In my controller file I do this: controller.h @class XMLParser; @interface controller : UIViewController { XMLParser *aXMLParser; } @property (nonatomic, retain) XMLParser *aXMLParser; controller.m #import "XMLParser.h" @synthesize aXMLParser; - (void)viewDidLoad { NSLog(@"test array: %@", aXMLParser.array); NSLog(@"test dict: %@", aXMLParser.dictionary); NSLog(@"test element: %@", aXMLParser.element); } When I test the value of my array, a dict or an element in the XMLParser.h file I get my result. What am I doing wrong so I can't call my results in my controller file? Any help is welcome, because I'm pretty stuck right now :/

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• Get the parent class of a null object (C# Reflection)

  - by Nick

  How would I get the parent class of an object that has a value of null? For example... 'Class A' contains 'int? i' which is not set to any value when the class is created. Then in some other place in the code I want to pass in 'i' as a parameter to some function. Using 'i' as the only info, I want to be able to figure out that 'Class A' "owns" 'i'. The reason for this is because 'Class A' also contains some other object, and I want to call this other object's value from that same function mentioned in the above paragraph. Could also be: public class A { public class B { public int? i; public int? j; } B classBInstance = new B(); public string s; } { ... A someClassAInstance = new A(); ... doSomething(someClassAInstance.classBInstance.i); ... } public static bool doSomething(object theObject) { string s = /* SOMETHING on theObject to get to "s" from Class A */; int someValue = (int)theObject; }

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• What are the disadvantages of self-encapsulation?

  - by Dave Jarvis

  Background Tony Hoare's billion dollar mistake was the invention of null. Subsequently, a lot of code has become riddled with null pointer exceptions (segfaults) when software developers try to use (dereference) uninitialized variables. In 1989, Wirfs-Brock and Wikerson wrote: Direct references to variables severely limit the ability of programmers to re?ne existing classes. The programming conventions described here structure the use of variables to promote reusable designs. We encourage users of all object-oriented languages to follow these conventions. Additionally, we strongly urge designers of object-oriented languages to consider the effects of unrestricted variable references on reusability. Problem A lot of software, especially in Java, but likely in C# and C++, often uses the following pattern: public class SomeClass { private String someAttribute; public SomeClass() { this.someAttribute = "Some Value"; } public void someMethod() { if( this.someAttribute.equals( "Some Value" ) ) { // do something... } } public void setAttribute( String s ) { this.someAttribute = s; } public String getAttribute() { return this.someAttribute; } } Sometimes a band-aid solution is used by checking for null throughout the code base: public void someMethod() { assert this.someAttribute != null; if( this.someAttribute.equals( "Some Value" ) ) { // do something... } } public void anotherMethod() { assert this.someAttribute != null; if( this.someAttribute.equals( "Some Default Value" ) ) { // do something... } } The band-aid does not always avoid the null pointer problem: a race condition exists. The race condition is mitigated using: public void anotherMethod() { String someAttribute = this.someAttribute; assert someAttribute != null; if( someAttribute.equals( "Some Default Value" ) ) { // do something... } } Yet that requires two statements (assignment to local copy and check for null) every time a class-scoped variable is used to ensure it is valid. Self-Encapsulation Ken Auer's Reusability Through Self-Encapsulation (Pattern Languages of Program Design, Addison Wesley, New York, pp. 505-516, 1994) advocated self-encapsulation combined with lazy initialization. The result, in Java, would resemble: public class SomeClass { private String someAttribute; public SomeClass() { setAttribute( "Some Value" ); } public void someMethod() { if( getAttribute().equals( "Some Value" ) ) { // do something... } } public void setAttribute( String s ) { this.someAttribute = s; } public String getAttribute() { String someAttribute = this.someAttribute; if( someAttribute == null ) { setAttribute( createDefaultValue() ); } return someAttribute; } protected String createDefaultValue() { return "Some Default Value"; } } All duplicate checks for null are superfluous: getAttribute() ensures the value is never null at a single location within the containing class. Efficiency arguments should be fairly moot -- modern compilers and virtual machines can inline the code when possible. As long as variables are never referenced directly, this also allows for proper application of the Open-Closed Principle. Question What are the disadvantages of self-encapsulation, if any? (Ideally, I would like to see references to studies that contrast the robustness of similarly complex systems that use and don't use self-encapsulation, as this strikes me as a fairly straightforward testable hypothesis.)

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