Question: What is Groovy?
Answer:
Apache Groovy is a object-oriented programming language for the
Java platform.
It is both a static and dynamic language with features similar
to those of Python, Ruby, Perl,and Smalltalk.
It can be used as both a programming language and a scripting
language for the Java Platform, is compiled to Java virtual machine (JVM)
bytecode, and interoperates seamlessly with other Java code and libraries.
Groovy uses a curly-bracket syntax similar to Java. Groovy
supports closures, multiline strings, and expressions embedded in strings.
And much of Groovy's power lies in its ASTtransformations,
triggered through annotations.
Question: Why Groovy Is Gaining Popularity?
Answer:
Here are few reasons for popularity of Groovy
รผ Familiar OOP language syntax.
รผ Extensive stock of various Java libraries
รผ Increased expressivity (type less to do more)
รผ Dynamic typing (lets you code more quickly, at least
initially)
รผ Native associative array/key-value mapping support (you
can create an associative array literal)
รผ String interpolation (cleaner creation of strings
displaying values)
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Question: What Is Meant by Thin Documentation In Groovy?
Answer:
Groovy is documented very badly. In fact the core documentation
of Groovy is limited and there is no information regarding the complex and
run-time errors that happen.
Developers are largely on there own and they normally have to
figure out the explanations about internal workings by themselves.
Question: How to Run Shell Commands in Groovy?
Answer:
Groovy adds the execute method to String to make executing
shells fairly easy
println "ls".execute().text
Question: In How Many Platforms you can use Groovy?
Answer:
These are the infrastructure components where we can use groovy:
-Application Servers
-Servlet Containers
-Databases with JDBC drivers
-All other Java-based platforms.
Question: Can Groovy Integrate with Non Java Based Languages?
Answer:
It is possible but in this case the features are limited. Groovy
cannot be made to handle all the tasks in a manner it has to.
Question: What are Pre-Requirements for Groovy?
Answer:
Installing and using Groovy is easy. Groovy does not have
complex system requirements. It is OS independent.
Groovy can perform optimally in every situation. There are many
Java based components in Groovy, which make it even more easier to work with
Java applications.
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Questions: What Is Closure In Groovy?
Answer:
A closure in Groovy is an open, anonymous, block of code that
can take arguments, return a value and be assigned to a variable. A closure may
reference variables declared in its surrounding scope. In opposition to the
formal definition of a closure, Closure in the Groovy language can also contain
free variables which are defined outside of its surrounding scope.
A closure definition follows this syntax:
{ [closureParameters -> ] statements }
Where [closureParameters->] is an optional comma-delimited
list of parameters, and statements are 0 or more Groovy statements. The
parameters look similar to a method parameter list, and these parameters may be
typed or untyped.
When a parameter list is specified, the -> character is
required and serves to separate the arguments from the closure body. The statements
portion consists of 0, 1, or many Groovy statements.
Question: What is ExpandoMeta Class In Groovy?
Answer:
Through this class programmers can add properties, constructors,
methods and operations in the task. It is a powerful option available in the
Groovy.
By default this class cannot be inherited and users need to call
explicitly. The command for this is “ExpandoMetaClass.enableGlobally()”.
Question: What Are Limitations of Groovy?
Answer:
Groovy has some limitations. They are described below
รผ It can be slower than the other object-oriented
programming languages.
รผ It might need memory more than that required by other
languages.
รผ The start-up time of groovy requires improvement. It is
not that frequent.
รผ For using groovy, you need to have enough knowledge of
Java. Knowledge of Java is important because half of groovy is based on Java.
รผ It might take you some time to get used to the usual
syntax and default typing.
รผ It consists of thin documentation.
Question: How To Write HelloWorld Program In Groovy?
Answer:
The following is a basic Hello World program written in Groovy:
class Test {
static void main(String[] args) {
println('Hello World');
}
}
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Question: How To Declare String In Groovy?
Answer:
In Groovy, the following steps are needed to declare a string.
The string is closed with single and double qotes.
It contains Groovy Expressions noted in ${}
Square bracket syntax may be applied like charAt(i)
Question: How to Test Groovy Application?
Answer:
The Groovy programming language comes with great support for
writing tests. In addition to the language features and test integration with
state-of-the-art testing libraries and frameworks.
The Groovy ecosystem has born a rich set of testing libraries
and frameworks.
Groovy Provides following testing capabilities Junit
Integrations Spock for specifications Geb for Functional Test.
Groovy also has excellent built-in support for a range of
mocking and stubbing alternatives.
When using Java, dynamic mocking frameworks are very popular.
A key reason for this is that it is hard work creating custom
hand-crafted mocks using Java.
Such frameworks can be used easily with Groovy.
Question: What Are Power Assertions In Groovy?
Answer:
Writing tests means formulating assumptions by using assertions.
In Java this can be done by using the assert keyword. But Groovy comes with a powerful
variant of assert also known as power assertion statement.
Groovy’s power assert differs from the Java version in its
output given the boolean
expression validates to false :
def x = 1
assert x == 2
// Output:
//
// Assertion failed:
// assert x == 2
// | |
// 1 false
This section shows the std-err output
The java.lang.AssertionError that is thrown whenever the assertion cannot be
validated successfully, contains an extended version of the
original exception message.
The power assertion output shows evaluation results from the
outer to the inner expression.
The power assertion statements true power unleashes in complex Boolean
statements, or
statements with collections or other toString -enabled classes:
def x = [1,2,3,4,5]
assert (x << 6) == [6,7,8,9,10]
// Output:
//
// Assertion failed:
// assert (x << 6) == [6,7,8,9,10]
// | | |
// | | false
// | [1, 2, 3, 4, 5, 6]
// [1, 2, 3, 4, 5, 6]
Question: Can We Use Design Patterns In Groovy?
Answer:
Design patterns can also be used with Groovy. Here are important
points
Some patterns carry over directly (and can make use of normal
Groovy syntax
improvements for greater readability).
Some patterns are no longer required because they are built
right into the language or because Groovy supports a better way of achieving
the intent of the pattern some patterns that have to be expressed at the design
level in other languages can be implemented directly in Groovy (due to the way
Groovy can blur the distinction between design and implementation)
Question: How to Parse And Produce JSON Object In Groovy?
Answer:
Groovy comes with integrated support for converting between
Groovy objects and JSON.
The classes dedicated to JSON serialisation and parsing are
found in
the groovy.json package.
JsonSlurper is a class that parses JSON text or reader content
into Groovy data
structures (objects) such as maps, lists and primitive types
like Integer, Double, Boolean and String.
The class comes with a bunch of overloaded parse methods plus
some special methods such as parseText , parseFile and others.
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