gradle members and tasks

gradle has a build file,typically build.gradle.This contains tasks,plugins,dependencies

example:
build.gradle
-----
task hello{
doLast {
println "Hello, Gradle"
}
}

>gradle hello

In the gradle file add below line,it will add all java related tasks for the gradle and with java folder structure.
apply plugin: 'java'

>gradle tasks -- lists all tasks
>gradle build -- compiles the java code.

a wrapper task example:
apply plugin: 'java'

task wrapper(type: Wrapper){
gradleVersion = '2.6'
}

>gradle wrapper
this creates a gradlew batch file.

gradlew build --> use this instead of normal gradle.so it uses the 2.6 version only.
the 2.6 version is extracted in .gradle folder of user directory.
In this way, we are carrying the version of gradle also along with gradle file.
----
task:
code that gradle executes.
-has a lifecyle.
-has properties
-has 'actions'
-has dependencies

example build file:
-----
project.task("Task1")

>gradle tasks

task("Task2")
task "Task3"
task Task4

>gradle tasks

as project is top level bject, no need to mention it.

to add properties to task:
-----
Task4.description = "Task 4 Description"

>gradle Task4

Task4.doLast {println "This is Task 4"}
Task3 << {println "This is task 3"}

task Task5 << {println "this is task 5"}
Task5 << {println "Another closure"}

>gradle Task5

task Task6{
 description "This is task 6"
 doLast{
   println "This is task 6"
 }
}

doLast and doFast... 
When we append with left shift operator << , it will add the actions to doLast.

Task6.doFirst{
println "Another first"
}

This will append at the top of code to doFirst.