Melquiades 3 3 bronze badges. Gaurav Thapa Gaurav Thapa 2 2 silver badges 5 5 bronze badges. Seems like you copy pasted this snippet from groovy-lang. The Overflow Blog. Does ES6 make JavaScript frameworks obsolete? Podcast Do polyglots have an edge when it comes to mastering programming Featured on Meta.
Now live: A fully responsive profile. Related 7. Hot Network Questions. Question feed. Accept all cookies Customize settings. In this example, we are creating a sum method with 2 parameters, a and b. Both parameters are of type int. We are then calling the sum method from our main method and passing the values to the variables a and b.
There is also a provision in Groovy to specify default values for parameters within methods. If no values are passed to the method for the parameters, the default ones are used. If both nondefault and default parameters are used, then it has to be noted that the default parameters should be defined at the end of the parameter list.
In this example, we are creating a sum method with two parameters, a and b. The difference between this example and the previous example is that in this case we are specifying a default value for b as 5. So when we call the sum method from our main method, we have the option of just passing one value which is 6 and this will be assigned to the parameter a within the sum method.
We can also call the sum method by passing 2 values, in our example above we are passing 2 values of 6. The second value of 6 will actually replace the default value which is assigned to the parameter b. This has neat implications with respect to imports. According to this page , def is a replacement for a type name and can simply be thought of as an alias for Object i.
However, variables defined using the keyword "def" are treated as local variables, that is, local to this one script. Variables without the "def" in front of them are stored in a so called binding upon first use. You can think of the binding as a general storage area for variables and closures that need to be available "between" scripts.
So, if you have two scripts and execute them with the same GroovyShell, the second script will be able to get all variables that were set in the first script without a "def". The reason for "def" is to tell groovy that you intend to create a variable here. It's important because you don't ever want to create a variable by accident. It's somewhat acceptable in scripts Groovy scripts and groovysh allow you to do so , but in production code it's one of the biggest evils you can come across which is why you must define a variable with def in all actual groovy code anything inside a class.
Here's an example of why it's bad. This will run Without failing the assert if you copy the following code and paste it into groovysh:. This kind of problem can take a lot of time to find and fix--Even if it only bit you once in your life it would still cost more time than explicitly declaring the variables thousands of times throughout your career. It also becomes clear to the eye just where it's being declared, you don't have to guess.
I think the only reason groovy allows you to do this in scripts is to support DSLs the way Ruby does A bad trade-off if you ask me, but some people love the DSLs. When I try to use a variable that I haven't declared with def or a type, I get an error "No such property", since it assumes that I'm using a member of the class containing the code. Stack Overflow for Teams — Collaborate and share knowledge with a private group.
Create a free Team What is Teams? This way, you can ensure that you don't add the same item twice if duplicates are not desirable for your purposes:. To remove an entry from the list, use the remove method. Note that this only removes the first occurrence of the item in the list, returning a boolean result indicating true if the desired item was found and removed. Therefore, if your list allows duplicates and you need to remove them all, you'll need to write a loop to call remove until it returns false.
You can iterate over the entries in a list using the for You can define an empty list using the square-bracket notation with nothing inside like this:. Notice that by default, the map key is assumed to be a string so you don't need to include the key values in quotes.
However, if any key value contains spaces you will need to use quotes around it like this:. If you want to use another type as the map key, you need to surround the key with parentheses. Consider the following example without the parentheses:.
The above example creates a map with key values of the strings x and y , rather than using the value of the variable x and the value of the variable y as map keys. To obtain this effect, surround the key expressions with parentheses like this:.
This creates a map with key values of the numbers 1 and 2. To reference the value of a map entry, use dot notation like this, using the may key value as if it were a field name on the map object:.
If the key value contains a literal dot character or contains spaces or special characters, you can also use the square-bracket notation, passing the key value as the operand:. This square bracket notation is also handy if the key value is coming from the value of a variable instead of a literal string, for example:. A map cannot contain duplicate key entries, so if you use put to put the value of an existing element, the existing value for that key is overwritten. You can use the containsKey function to test whether or not a particular map entry already exists with a given key value, or you can use the containsValue function to test if any map entry exists that has a given value — there might be zero, one, or multiple entries!
To remove an entry from the map, use the remove method. It returns the value that was previously associated with the key passed in, otherwise it returns null if it did not find the given key value in the map to remove.
You can define an empty map using the square-bracket notation with only a colon inside like this:. Using ranges, you can conveniently creates lists of sequential values. If you need to work with a list of integers from 1 to , rather than creating a list with literal numbers in it, you can use the..
The range is particularly useful in performing iterations over a list of items in combination with a for loop like this:.
Of course, you need not assign the range to a variable to use it in a loop, you can use it inline like this:. Previous Next JavaScript must be enabled to correctly display this content.
Groovy Basics This section highlights some important aspects of Groovy to allow you to better understand the examples in the sections that follow. Commenting Your Scripts It is important that you document your scripts so that you and your colleagues who might view the code months from now will remember what the logic is doing. See the tip in Using Substitution Expressions in Strings below for more information. Referencing the Value of a Field in the Current Object When writing scripts that execute in the context of the current business object, you can reference the value of any field in the current object by simply using its API name.
See the tip in the Using Substitution Expressions in Strings for more information. Working with Numbers, Dates, and Strings Groovy makes it easy to work with numbers, dates and strings. Write a literal string using a matching pair of single quotes, as shown here. Using Substitution Expressions in Strings Groovy supports using two kinds of string literals, normal strings and strings with substitution expressions.
Tip: As a rule of thumb, use normal single-quoted strings as your default kind of string, unless you require the substitution expressions in the string.
If the primary email address contains a '. AlternateEmailAddress : EmailAddress. Using the Switch Statement If the expression on which your conditional logic depends may take on many different values, and for each different value you'd like a different block of code to execute, use the switch statement to simplify the task.
Returning a Boolean Result Two business object contexts expect your groovy script to return a boolean true or false result.
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