When is a field null? IsBlank will consider a formula blank as NOT blank. Aku berlari ke beberapa kode yang berikut ini: Ini muncul secara fungsional setara dengan berikut ini: Perbedaan antara dua (`org.apache.commons.lang3.StringUtils.isBlank` dan `jawa.lang.String.isEmpty`)? * Returns `true` if the character is whitespace. 12 - Quasar 01-13-2020 05:54 AM. We've also created a function isNullOrEmpty() which checks, as the name suggests, whether the string is null or empty. It checks it using a null check using != null and isEmpty() method of string. StringUtils join() Example in Java . Discussion about Kotlin, a statically typed programming language for the JVM, Android, JavaScript, and native. I intentionally left out covering every single thing as I wanted to cover only the new language features. IsBlank(ComboBox1.SearchText) This is such a trivially small amount that there's no reason to worry about which one you use from a performance perspective. The difference between both methods is that isEmpty() method returns true if, and only if, string length is 0. isBlank() method only checks for non-whitespace characters. I wrote about their difference. Remarks. The IsEmpty() function is used to check if a table contains any records, in other words, the IsEmpty() function is used to detect if there is no records within a Table. Difference between isBlank(), isNull() and isEmpty() functions The table below lists the (boolean) values that isBlank(), isNull(), isEmpty() functions return on various possible input values below. ISEMPTY(
) Parameters. kotlin-stdlib / kotlin.text / isBlank. Thread starter JADownie; Start date Jan 3, 2013; J. JADownie Active Member. isEmpty is the same as comparing to zero string (value Copying and replication of the contents of this site, text and images are strictly prohibited. 在kotlin的使用中,经常会遇到字符串判空的问题 ,而且kotlin提供了很多实现不同功能的方法: 这些方法基本都能根据字面意思去理解用法 。但其中频繁出现的empty和blank,却不太容易知道该怎么用,下面,就来解释一下,这两大类的区别。1、str.isEmpty()表示:str == null || str.length == 0 2、str.isBlank()表 … Kotlin String has methods, isBlank() and isEmpty(). Kotlin 1.3.41 . Return value. To check whitespace we can use isBlank() method. It does not check the string length. TRUE for non-blanks and FALSE for blanks. == operator in Kotlin only compares the data or variables, whereas in Java or other languages == is generally used to compare the references. isNull takes a single parameter and returns a Boolean value. Außerhalb von Funktionen akzeptiert Kotlin keine Befehle. difference between isblank() and isspace() The isspace() simply return true if the character is a space. * Returns `true` if this char sequence is empty (contains no characters). Supported and developed by JetBrains Supported and developed by JetBrains * Returns `true` if this string is empty or consists solely of whitespace characters. Java String isEmpty() The java string isEmpty() method checks if this string is empty or not. 1 ACCEPTED SOLUTION JoyCornerstone. It not only checks if the String is not empty and not null, but also. Synchronization In Java With Example. [Kotlin] isEmpty(), isBlank()などの違い早見表 . Kotlin™ is protected under the Kotlin Foundation and licensed under the Apache 2 license. In this case, Nothing is used to declare that the expression failed to compute a value.Nothing is the type that inherits from all user-defined and built-in types in Kotlin.. Many data sources can store and return NULL values, which are represented in Power Apps as blank. The IsBlank() function is used to check if a value is Blank. StringUtils isEmpty() returns true if string is empty or null. Given a string, we have to check whether it is an empty, blank or NULL string. From the linked documentation: Checks if a String is whitespace, empty (“”) or null. IsBlank( AnyCollection) Because the collection exists, it isn't blank, even if it doesn't contain any records. Term Definition; table_expression: A table reference or a DAX expression that returns a table. If you want to do the same in Excel, a similar function is the IsBlank function. fun CharSequence.isBlank(): Boolean . !IsBlank() and !IsEmpty() for combo box 01-19-2019 07:28 PM. Else, it is. ChrisTX. We also covered isNotEmpty() and isNotBlank() methods. Describes when there is nothing inside(content). I would suggest creating the column in the query editor. 3. isBlank() vs isEmpty() Both methods are used to check for blank or empty strings in java. Checks if the value is null, empty, or contains only whitespace characters. You can use ISBLANK to check for holes or gaps in user input.. As we will see a bit further in our discussion, we can use the results of ISBLANK within another formula like an IF. This function is not supported for use in DirectQuery mode when used in calculated columns or row-level security (RLS) rules. 2. isBlank Method examples Let us write a program to check the given string is empty or not. 2.1 isBlank() Example 1 Both methods are used to check for blank or empty strings in java. [SOLVED] Blank cell vs empty cell; Results 1 to 13 of 13 Blank cell vs empty cell. Please don’t misunderstand this equality operator with the Java == operator as both are different. Jan 3, 2013 #1 Hello - I have the below macro which loops through 85 lines on my sheet and hides the row if column A is empty. uses the isNull operator to check the field value of country_code and if it returns true has the if operator replace the value with the string unknown: To check for null values from a lookup operation, use a query like: | parse "example_ip=*]" as ip Kotlin führt den Inhalt von main() automatisch aus. You may be better off testing as follows if you want cells with formulas that return null strings to be considered empty:?Cells(1, 1) = "" False--Vasant It's, of course, pretty common to know when a string is empty or blank, but let's make sure we're on the same page with our definitions. str1 contains null value and str2 is an empty string. Header File: ctype.h Declaration: int isblank(int ch) . Note that this is not an extensive list and there are high chances that I might have missed some special white space Unicode characters. Blank is a placeholder for "no value" or "unknown value." This is totally different than just checking if the string is empty. Hello, guys. 0 Likes Share. Joined Dec 11, 2007 Messages 359. We've also created a function isNullOrEmpty() which checks, as the name suggests, whether the string is null or empty. StringUtils isBlank Vs isEmpty บทความนี้ผมจะมาทดลองใช้ isBlank กับ isEmpty ดูว่ามันต่างกันยังไง โดยใช้ Lib ของ apache.commons.lang3.StringUtils ไปดูกันเลยคับ เริ่มจากโค้ดที่ใช้ทดสอบ Best How To : StringUtils.isBlank() checks that each character of the string is a whitespace character (or that the string is empty or that it's null). Describes facial expression/missing surface content. Fakt. Hi @ivyhai,. Environment Kotlin 1.2.0 Empty Empty means no-content. Open Live Script. I have a job to do to my boss. Used in emotional/content-related/idea-related context. “\s*”. Summary – We have seen StringUtils isEmpty() and IsBlank() Example in Java. Syntax public boolean isBlank() Basically, isBlank() method returns true if the string is empty or contains only white space codepoints, otherwise false. StringUtils.isBlank vs String.isEmpty 215 . isEmpty sprawdza tylko, że długość sekwencji char jest 0. The most convenient way is to use Apache Commons Lang, which provides helpers such as StringUtils.isBlank. From the linked documentation: Checks if a String is whitespace, empty (“”) or null. Kotlin 1.3 - kotlin.text.isBlank . A field is not empty if it contains a character, blank space, or zero. This is similar to Microsoft Exce… Go to Solution. If you want to do the same in Excel, a similar function is the IsBlank function. This is totally different than just checking if the string is empty. Supported and developed by JetBrains | if (isNull(country_code), "unknown", country_code) as country_code. In Kotlin lassen sich Functions, die nur eine Zeile Code umfassen, vereinfacht darstellen. For example, a field that contains a space inserted with the spacebar is not empty. Get code examples like "isblank vs isempty" instantly right from your google search results with the Grepper Chrome Extension. kotlin-stdlib / kotlin.text / isBlank. Let’s see several examples of isBlank vs isEmpty usage and notice the differences. Rolliee (Programmer) 25 Apr 03 16:38 null plus anything is null. The isNull operator checks a string and returns a boolean value: true if the string is null, or false if the string is not null. String isBlank(), 3. isBlank() vs isEmpty(). Both methods are used to check for blank or empty strings in java. Saya mengalami beberapa kode yang memiliki yang berikut: ... Mungkin perlu disebutkan bahwa ada juga StringUtils.isEmpty(foo)yang membantu Anda menghindari pointer nol, seperti isBlank, tetapi tidak memeriksa karakter spasi. .isEmpty() is used to find if the String is length 0 or null..isBlank() takes it a step forward. isBlank sprawdza, czy sekwencja znaków ma długość 0 lub czy wszystkie indeksy są białymi znakami. isEmpty() method returns true if, and only if, length of the string is 0. while on the other hand, isBlank method checks for non-white characters only, it doesn’t check the string length. Resolver II In response to Stuznet. Nur Deklarationen sind dort erlaubt. TF = isempty(A) returns logical 1 (true) if A is empty, and logical 0 (false) otherwise. false: IsBlank( Mid( "Hello", 17, 2 ) ) The starting character for Mid is beyond the end of the string. Tips:: Use ISBLANK instead of ISNULL in new formulas. To check for an empty collection, use IsEmpty instead. RE: IsNull vs IsEmpty? Referential equality (‘===’) === operator is used to compare the reference of two variable or object. With a Worksheet Cell. The ISBLANK formula field returns a TRUE while the ISNULL does not.This is because, when a Text field is left EMPTY, it is internally assigned with an EMPTY STRING and hence it is not NULL.The technical meaning of NULL is that it is not assigned with a memory for storage.Since we need some memory for storing an EMPTY STRING, it is obviously not NULL. Kotlin prepares methods similar to isEmpty and isBlank. If we want to stick to plain Java, we can use a combination of String#trim with either String#isEmpty or String#length. Kotlin: Why Break or Continue can’t be used in forEach or repeat, while for and while can use them, Kotlin: Difference between Blank and Empty, Kotlin: String Conversion – First Letter to Lower/Upper, Camel Case and Snake Case, I’ve Written Cover Story 2 in WEB+DB PRESS Vol. Hi @ericonline,. Jawaban: 380 . Column = IF(ISBLANK('Table1'[DaysBetweenDates]),BLANK(),IF(''Table1'[DaysBetweenDates]< 46,"< 45 Days","45+ Days")) Thanks. true: IsBlank… In definition of the method, it calculate String’s length and compares it to zero. isNull() isEmpty() isBlank() Examples; The isNull operator checks a string and returns a boolean value: true if the string is null, or false if the string is not null.. =NOT(ISBLANK(A2)) Copy the formulas down to a few more cells and you will get this result: ISBLANK in Excel - things to remember. It does not check the string length. Show Printable Version; Subscribe to this Thread… Rate This Thread. For Bean Validation, regular expressions can be used instead. collapse all. In plain terms, if a string isn't a null and isEmpty() returns false, it's not either null or empty. In addition to isNull: The isEmpty operator checks if a string . I wrote about their difference. 08/27/2019; 2 นาทีในการอ่าน ; g; ในบทความนี้. ="" will count Forumula Blanks as blank, where IsBlank will not. It checks it using a null check using != null and isEmpty() method of string. String isBlank() vs isEmpty() References: White Space Unicode Code Points in Java. 3. isBlank() vs isEmpty() Both methods are used to check for blank or empty strings in java. isBlank. It checks it using a null check using != null and isEmpty() method of string.. IF IsEmpty vs. | lookup country_name, city from geo://location on ip = ip Run a geo lookup query where we can find remote IP addresses that are not in the geo database. Empty means no-content. * Determines whether a character is whitespace according to the Unicode standard. Diese Funktion stellt den Einstiegspunkt in ein Kotlin-Programm dar. Make sure to check out all these samples over on GitHub. In plain terms, if a string isn't a null and isEmpty() returns false, it's not either null or empty.Else, it is. The isblank()function returns non-zero if ch is a character for which isspace() returns true and is used to separate words.Thus for English, the blank characters are space and horizontal tab. Return value. So emptier, emptiest, blanker, blankest are valid words, but they are not used frequently. ฟังก์ชัน Blank Coalesce IsBlank และ IsEmpty ใน Power Apps. Learn more about ISEMPTY in the following articles: Check Empty Table Condition with DAX. In doing so you can use the TRIM function to ensure that there are no leading or trailing spaces. Based on your issue that you provided, I think you have some misunderstanding with IsBlank() function and IsEmpty() function.. More details about IsBlank () function and IsEmpty () … For example, a Boolean value normally has one of two values: true or false. And Kotlin isWhitespace method uses Java’s methods, isWhitespace and isSpaceChar. In this situation, no country_code will be associated with the IP address and the field value will be null. The difference between both methods is that isEmpty() Often, we also want to check if a string is blank, meaning that it consists of only whitespace characters. True if the table is empty (has no rows), if else, False. Using the IsEmpty function in VBA. Reference 112 . ISBLANK has the same functionality as ISNULL, but also supports text fields. String API has another method isEmpty() which also checks the string is empty or not. ==operator is used to compare the data of two variables. blank form, blank sheet, blank piece of paper, blank computer screen. Kotlin™ is protected under the Kotlin Foundation and licensed under the Apache 2 license. isEmpty finds strings containing no characters/whitespace; isBlank finds strings made up of only whitespace/null. Java considers the following characters as white space. To Quote the API. To check if A2 is not empty, use ISBLANK together with the NOT function, which returns the reversed logical value, i.e. empty and blank are adjective. The isEmpty() method of String class is included in java string since JDK 1.6. Returns true if this string is empty or consists solely of whitespace characters. Submitted by IncludeHelp, on April 27, 2020 . Let's look at both of these cases. 109, Google Drive: Stop Automatic Conversion ” and ‘ to “” and ‘’, Excel in Mac: How to Remove Error Notification, Java: Get Standard Input from System.in without Scanner, (日本語) WordPress プラグイン “Hello Dolly” はなにをやっているの?, (日本語) 2019年6月 東京都葛飾区のタバコのルール 条例で定められた禁止事項と罰則. In this step-by-step tutorial, for all levels of Excel and VBA users, you will see how to use both functions. The result is an empty string. For Java, whitespaces are characters like spaces, tabs and so on. | lookup country_code from geo://location on ip = remote_ip ISBLANK will determine that a cell is empty only if if contains nothing.. It checks it using a null check using != null and isEmpty() method of string.. In this article, you will learn how to use the IsEmpty function in VBA to check if a cell is empty. 1) isEmpty. In Kotlin, throw returns a value of type Nothing. It returns true, if length of string is 0 otherwise false.In other words, true is returned if string is empty otherwise it returns false. If you wish to test whether a worksheet cell is empty in VBA, you can not use the worksheet function called ISBLANK. LinkBack. We've also created a function isNullOrEmpty() which checks, as the name suggests, whether the string is null or empty. isEmpty is the same as comparing to zero string (value == ""). Any property or calculated value in Power Apps can be blank. Fields can hold a null value for the following reasons: Checks if the value is an empty string containing no characters or whitespace. The IsBlank () function is used to check if a value is Blank. FYI a Combobox contains a Table, even if it contains a single item or one column, so the appropriate function to test it would be IsEmpty() rather then IsBlank(). StringUtils.isBlank() checks that each character of the string is a whitespace character (or that the string is empty or that it’s null). Nothing to see. Kotlin | Check for empty string: Here, we are going to learn how to check whether a given string is an empty, blank or NULL string in Kotlin programming language? == operator in Kotlin only compares the data or variables, whereas in Java or other languages == is generally used to compare the references. Blank means non-filled, not-printed. RELATED ARTICLES MORE FROM AUTHOR. An empty array, table, or timetable has at least one dimension with length 0, such as 0-by-0 or 0-by-5. Example: Input: str = "" Output: True But blank only mean empty string. StringUtils.isBlank() checks that each character of the string is a whitespace character (or that the string is empty or that it’s null). Android Kotlin. I’ve tried to make this as comprehensive as possible without getting too detailed, and provide examples to make things clearer. Returns true if the string is null or empty. But in addition to these two, it can also be blank indicating that the state is not known. isNull, isEmpty, isBlank - … isBlank to nie to samo co isEmpty i to naprawdę zależy od twojego przypadku użycia. Vacent. LinkBack URL; About LinkBacks; Thread Tools. The IsEmpty () function is used to check if a table contains any records, in other words, the IsEmpty () function is used to detect if there is no records within a Table. | parse "remote_ip=*]" as remote_ip If you use ISEMPTY to test a RANGE, it works the same as ISBLANK. Remarks. When to use isNull, isEmpty, isBlank. We consider a string to be empty if it's either null or a string without any length. We can use the ISEMPTY function to test a worksheet cell or a variable. Contributing to Kotlin Releases Press Kit Security Blog Issue Tracker. contains no characters String.isEmpty is marginally faster (~0.00219ms vs ~0.00206ms, about 6%). IF Is BLANK. This is totally different than just checking if the string is empty. Current Rating Excellent Good Average Bad Terrible 10-31-2019, 10:54 AM #1. public static boolean isEmpty(String str) Checks if a String is empty (“”) or null. — Xavi . The negated counterpart of == in Kotlin is != which is used to compare if both the values are not equal to each other. fun CharSequence.isBlank(): Boolean. StringUtils.isNotBlank() takes it a step forward. そもそも、なぜこの記事を書こうと思ったのかと言うと、PHPのメソッドの早見表はあるのに、Kotlinが無いな・・・。って思っただけです。 文字比較の早見表. Term Definition; table_expression: A table reference or a DAX expression that returns a table. Hope that clears up a little.. null times anything is null. Salesforce will continue to support ISNULL, so you do not need to change any existing formulas. The difference between both methods is that isEmpty() method returns true if, and only if, string length is 0. isBlank() method only checks for non-whitespace characters. /** * Returns `true` if this string is empty or consists solely of whitespace characters. This is important to be aware of since cells that contain spaces or empty strings are not actually empty. null just does not have any other rules to obey. Labels: Labels: Need Help; Show and Tell; Tutorial Requests; Message 1 of 7 40,804 Views 0 Reply. However, you can use IsBlank to test whether there is text in the Combobox's search property. This function is not supported for use in DirectQuery mode when used in calculated columns or row-level security (RLS) rules. Returns true if the array is empty.. In DAX there are different ways to test whether a table is empty. 43.2k members in the Kotlin community. Solved! This test can be used in complex DAX expressions and this short article briefly discuss what are the suggested approaches from a performance perspective. In plain terms, if a string isn't a null and isEmpty() returns false, it's not either null or empty.Else, it is. For example, a Combo box control's Selected property is blank if the user hasn't made a selection. Example . Examples. Practically speaking, you should generally use String.isBlank if you expect potentially whitespace strings (e.g. IsEmpty(), while it seems to work for really empty cells, is meant to determine if a variable has been initialized. Returns true if the string is null, empty, or only whitespace. However, the above program doesn't return empty if a string contains only whitespace characters (spaces). ISEMPTY() Parameters. I creater a powerapps screen that saves data in a Sharepoint List, but one field of this screen, a combo box, receives data from the List to charge the choices available. Losguapos1. StringUtils.isNotEmpty() is used to find if the String is not empty and not null. Kotlin™ is protected under the Kotlin Foundation and licensed under the Apache 2 license. In this article, you will learn how to use the IsEmpty function in VBA to check if a cell is empty. Kotlin 1.3.41 . | where isNull(country_name). IsBlank and ="" should be used to test if a RANGE is blank. It not only checks if the String is length 0 or null, but also checks if it is only a whitespace string, i.e. Kotlin String has methods, isBlank() and isEmpty(). » Read more. The ISEMPTY function can only be used in VBA code in Microsoft Excel. In this post I will go over most of the new features and how to use them. Single parameter and returns a table reference or a variable it can also be.... Am # 1 amount that there are high chances that i might have some... Data sources can store and return null values, which provides helpers as! Values, which returns the reversed logical value, i.e a Boolean value. ) function and (... Geo lookup query where we can use the isEmpty operator checks if a cell is empty function, returns! And native ] isEmpty ( ) example in java isEmpty ใน Power Apps use isBlank to test a is. Will determine that a cell is empty ( “ ” ) or.. Not an extensive list and there are high chances that i might have missed some special White space Code. The state is not an extensive list and there are no leading or trailing spaces this is such a small! It blank it checks it using a null check using! = null and isEmpty ( ) function and (. Or null to find if the table is empty ( “ ” ) or null Boolean isEmpty ). And returns a value is blank about isEmpty in the Combobox 's search property obey. There 's no reason to worry about which one you use isEmpty to test a worksheet cell empty! If else, false vereinfacht darstellen string isEmpty ( ) for Combo box 01-19-2019 07:28 PM performance.! Query editor string ( value == `` '' ) ( string str checks! Of only whitespace/null ISNULL in new formulas == `` '' Output: true String.isEmpty is marginally (! Expressions and this short article briefly discuss what are the suggested approaches from a performance perspective, że długość char... Długość sekwencji char jest 0 ) … [ Kotlin ] isEmpty ( ) method nur eine Zeile Code umfassen vereinfacht... Examples to make things clearer Message 1 of 7 40,804 Views 0 Reply isBlank together with the java isEmpty! To make this as comprehensive as possible without getting too detailed, so! Site, text and images are strictly prohibited Code examples like `` isBlank vs isEmpty ( ) and (! Can only be used instead and licensed under the Kotlin Foundation and licensed under the Foundation... Is n't blank, where isBlank will consider a string is whitespace according to the Unicode standard make clearer. Białymi znakami articles: check empty table Condition with DAX string only consists of whitespace characters wszystkie są. Empty string empty or not i might have missed some special White space Unicode Code Points in string... Unicode standard: a table reference or a variable has been initialized i will go over most of new! Addition to these two, it is n't blank, where isBlank consider... But in addition to these two, it calculate string ’ s see several examples of isBlank vs isEmpty )! Value is blank for really empty cells, is meant to determine if string! Row-Level security ( RLS ) rules content ) string ( value == `` '' Output true! This Thread that this is totally different than just checking if the value is null but... Excel and VBA users, you will see how to use Apache Commons Lang, which helpers. The new features formula blank as not blank isEmpty ใน Power Apps can be to! Worksheet function called isBlank mode when used in complex DAX expressions and this short article briefly discuss what the... Wszystkie indeksy są białymi znakami Rating Excellent Good Average Bad Terrible 10-31-2019, 10:54 #!, as the name suggests, whether the string is empty which one you use isEmpty to whether. Different ways to test whether there is nothing inside ( content ) ===... Geo lookup query where we can find remote IP addresses that are not in the geo.... It calculate string ’ s see several examples of isBlank vs isEmpty usage and notice the.. As i wanted to cover only the new features and how to use Apache Commons Lang, which helpers... Whitespace characters empty cell to ISNULL: the isEmpty operator checks if this string is whitespace according to Unicode! Solved ] blank cell vs empty cell ; Results 1 to 13 of blank... Space, or contains only whitespace characters as StringUtils.isBlank from the linked:. 1 Summary – we have seen StringUtils isEmpty ( ) method of string null value and is... A Combo box 01-19-2019 07:28 PM examples to make things clearer only whitespace Let us a... Table, or only whitespace characters blank cell vs empty cell ; 1. Javascript, and logical 0 ( false ) otherwise is to use functions! Language features you wish to test if a string to be aware of since cells that spaces! Geo database covered isNotEmpty ( ) returns logical 1 ( true ) if string! Provide examples to make things clearer strings in java for invisible characters, for. Be associated with the java == operator as both are different ways to test a worksheet or... Created a function isNullOrEmpty ( ) and isBlank ( ) simply return true if the user has n't made selection... We can find remote IP addresses that are not actually empty SOLVED ] blank cell vs empty cell other to... Isempty sprawdza tylko, że długość sekwencji char jest 0 's Selected property is blank if the character is space. Make this as comprehensive as possible without getting too detailed, and native 13 blank cell vs empty cell Results... ; Results 1 to 13 of 13 blank cell kotlin isblank vs isempty empty cell a table value str2. Or row-level security ( RLS ) rules samo co isEmpty i to naprawdę zależy od twojego przypadku użycia to., also for wide space and CR, LF, and provide examples to make this comprehensive. Character is a placeholder for `` no value '' or `` unknown value.,. That there are no leading or trailing spaces remote IP addresses that not... Or consists solely of whitespace characters diese Funktion stellt den Einstiegspunkt in Kotlin-Programm. Empty string the value is blank collection, use isBlank ( ) function and isEmpty ( ) is! Only checks if a string ma długość 0 lub czy wszystkie indeksy są białymi znakami Average Bad Terrible... Is not known wanted to cover only the new language features just does not have any other rules to.... Contain any records no rows ), isBlank ( ) and isspace ( ), if,..., Android, JavaScript, and provide examples to make things clearer ใน Power Apps programming language for the,... Works the same in Excel, a kotlin isblank vs isempty value. value and str2 is an string. It to zero string ( value == `` '' ) or null supported and developed JetBrains... Method, it is an empty string kotlin™ is protected under the Apache 2 license isEmpty operator checks a! In Excel, a Combo box control 's Selected property is blank meant to determine if a string only of. By JetBrains supported and developed by JetBrains supported and developed by JetBrains Kotlin string has methods, isBlank ( などの違い早見表. Trailing spaces JetBrains! isBlank ( ) and! isEmpty ( ) 3....