Grails Note four: Groovy feature summary

Working with Groovy while learning grails is unavoidable, though not too deep, but it's also helpful to know a few features.

1. Get integers after dividing

Use the intdiv () method to get an integer, note that this method only applies to dividing two integers , floating-point numbers do not

If,while acceptable type of 2.Groovy

• Boolean
• Number 0 is false, others are true
• String null character "" is false, others are true
• The object is null when False, others are true
• Collection Set Property Length=0 false, others true

3. How closures are accessed

The closures and methods in groovy are similar in that they are called directly in two ways:

Define a closure def CLOS={PRINTLN it}//first closure call Clos.call (' Obama ')///second closure call Clos (' dumb pull-out light ')

How the key value of map in 4.Groovy is a variable

In groovy, the key value of map is a string by default, and if you want the key value to be a variable, enclose the variable in ():

def x= ' 123 ' Def map=[(x): 45]println map.tostring ()

Two different points of the 5.Groovy class and the Java class

1.Groovy class has a default constructor based on map initialization

Constructs a groovy class cs{    String name}//instantiation def C=new CS (name: ' Tita ')//or Def CC=NEW cs ([Name: ' TT '])

The attribute field of the 2.Groovy class does not have an access qualifier defined, and the default is private

Class a{string name}//equivalent class a1{    private string name public    string GetName () {        name    } public    void SetName (String name) {        this.name=name    }}def a=new A (name: ' TT ')//i.e. the following equivalent println a.nameprintln a.getname ()

The use of the * number operator for 6.List

The list has a very useful operator,--*, which is useful in two cases:

1. Place the * number behind a list object, such as

def list=[1,2,3]def Temp=list*.intdiv (2) println Temp

At this point, each element in the list object calls the method that follows the *, and the return is still a list object

2. Put in front of the range, such as:

　

def range=0..9def Temp=[*range]println Temp

Note [] is necessary because this way is to expand the scope to generate a list object

Grails Note four: Groovy feature summary