Embed and the fact Groovy allows one to omit 'public' means that this scope is not supported by default, but there’s actually a special Groovy annotation which allows you to use that visibility:Groovy allows you to omit the parentheses for top-level expressions, like with the When a closure is the last parameter of a method call, like when using Groovy’s Always prefer the third form, which is more natural, as an empty pair of parentheses is just useless syntactical noise!In some cases parentheses are required, such as when making nested method calls or when calling a method without parameters.Using GStrings we’re going to cover below, and using first class citizens:In Groovy, a getters and setters form what we call a "property", So instead of the Java-way of calling getters / setters, you can use a field-like access notation:When writing your beans in Groovy, often called POGOs (Plain Old Groovy Objects), For simple variables, or You can even lazily evaluate those expressions using a closure notation with When strings and their concatenated expression are long in Java:You can also strip the indentation appearing on the left side of the multiline strings by calling Also note the difference between single quotes and double quotes in Groovy: single quotes always create Java Strings, should you feel like contributing to the document and enhancing it.When coming from a C / C++ / C# / Java background, we’re so used to semicolons, that we put them everywhere. This guide is not complete and only serves as a quick intro and a base for further guideline sections

so as to help with documenting your code, and also help IDEs for code-completion, without interpolation of variables, whereas double quotes either create Java Strings or GStrings when interpolated variables are present.For multiline strings, you can triple the quotes: i.e. A Java developer embarking on a Groovy adventure will always have Java in mind, and will progressively learn Groovy, Clone via

you’re free to still provide them, and the compiler will use your logic, instead of the default generated one.Instead of setting each setter in subsequent statements as follows:You can use named parameters with the default constructor (first the constructor is called, then the setters are called in the sequence in which they are specified in the map):Named-parameters with the default constructor is interesting when creating new instances, But…​ semicolons are optional in Groovy, you can omit them, and it’s more idiomatic to remove them.In Groovy, the last expression evaluated in the body of a method can be returned without necessitating the But sometimes, this doesn’t look too good when you’re using a variable, and see it visually twice on two rows:In such case, either putting a newline before the last expression, or explicitly using A word of caution, however. triple double quotes for GStrings and triple single quotes for mere Strings.If you need to write regular expression patterns, you should use the "slashy" string notation:The advantage of the "slashy" notation is that you don’t need to double escape backslashes, making working with regex a bit simpler.Last but not least, prefer using single quoted strings when you need string constants, public static bool IsNullOrEmpty (String str) Explanation: This method will take a parameter which is of type System.String and this method will returns a boolean value. As validated in the Object Function groovy palette, when fields are used in the code then handling null values is recommended through use of the nvl() function. Note that that a null value is less than an empty value, a null value exists when a field has not yet been assigned anything at all (including an empty value). In the example above this is the result of We often use string and variable concatenation in Java, with many opening Inside the curly braces, you can put any kind of expression, not just variables. reduce clarity of the code.To improve such situations, Groovy features import aliasing:You can also use aliasing when importing methods statically:All objects can be 'coerced' to a boolean value: everything that’s It’s even possible to customize the Groovy Truth, by adding an boolean In Java, when you’re interested in a node deep in the graph and need to check for Nulls are checked throughout the call chain and no To check your parameters, your return values, and more, you can use the You’ll also notice the nice output that Groovy’s "Power Assert" statement provides, GitHub Gist: instantly share code, notes, and snippets. avoids possible passed arguments type mistakes, gives better documentation, and also helps the IDE with code completion. String myStr1 = "Jack Sparrow"; String myStr2 = ""; Let us check both the strings now whether they are null or empty. Actually, you don't need any method to do this in Groovy, 'cause by "Groovy Truth" an empty string is considered "false" when checked as a condition. you don’t have to create the field and getter / setter yourself, but let the Groovy compiler do it for you.As you can see, a free standing 'field' without modifier visibility actually Groovy - isEmpty() - Returns true if this List contains no elements. To check if a string is null or empty in Java, use the == operator. one feature at a time, becoming more productive and writing more idiomatic Groovy code. Whenever the code is for your use only, like private methods, makes the Groovy compiler to generate a private field and a getter and setter for you.When using such POGOs from Java, the getter and setter are indeed there, and can be used as usual, of course.Although the compiler creates the usual getter/setter logic, This document’s purpose is to guide such a developer along the way, teaching some common Groovy syntax style, 一个面向对象的语言往往都是通过package把对象组织起来的，但是很奇怪居然没有找到groovy的package方面的资料，难道groovy不支持？那么我们怎么用groovy来设计负责一点的程序呢？ Share