Differences Between Java and Groovy

Groovy is an object-oriented programming language for the Java platform. People who don’t like to use Java coding can use Groovy for their web development projects. As Groovy is mostly used by Java developers, the team behind this programming language tried to keep it as simple as possible so that newbie coders with a Java background don’t get confused. However, there are some key differences between Java and Groovy. Read the following paragraphs to know about those differences.

Default import

The packages and classes mentioned below are imported by default. Therefore, there is no need to use the “import” statement to use them.

  • java.io.*
  • java.lang.*
  • java.math.BigDecimal
  • java.math.BigInteger
  • java.net.*
  • java.util.*
  • groovy.lang.*
  • groovy.util.*

Common confusions faced by Java developers

  • The Java syntax is quite confusing and if you are used to with that confusing style, then Groovy, despite being simpler, may perplex you. In Java, == means “equality” for primitive types and == means “identity” for objects. However, in Groovy, == means equals, no matter what type you are using. If you are in dire need of “identity”, you can use the “is” method.
  • In Groovy, “in” is a keyword, so don’t use it as a variable name.
  • While declaring “array”, you can’t write int[] a = {1,2,3}; instead you need to write int[] a = [1,2,3].

Things first-time Groovy users should be aware of

  • Semicolons are optional, but if you want to put multiple statements in one line, you have to use them.
  • Use “this” keyword inside static methods, which refers to “this” class.
  • The use of the “return” keyword is optional.
  • “protected” is the same in Java and Groovy.
  • By default, “methods” and “classes” are unrestricted.
  • Inner classes, non-static, are not supported in Groovy. To implement interfaces, you can use “closures”. However, static nested classes are supported.
  • The Groovy compiler does not check the “throws” clause in a method signature.
  • In Java, you get compile errors if you use undefined members or pass wrong type arguments, but Groovy does not show such errors.

Some of the exclusive features of Groovy which are not available in Java

  • Closures.
  • The native syntax for maps and lists.
  • GPath and GroovyMarkup support.
  • Native support for regular expressions.
  • Strong switch statement and polymorphic iteration.
  • Static and dynamic typing is supported.
  • Programmers have the freedom to embed expressions inside strings.
  • The JDK comes with lots of new helper methods.
  • The easy syntax for writing “beans”.
  • Safe navigation with the help of the?. operator.