Weapons for Boilerplate Destruction

Weapons for Boilerplate
DESTRUCTION
Tomás Ruiz López
Everyware Technologies
Droidcon Spain 2015@tomasruizlopez
tomas@everywaretech.es

Tomás Ruiz-López
Software Design Manager at Everyware Technologies
@tomasruizlopez
@everywaretech
/everywaretech
http://www.everywaretech.es
WHO AM I?
Postdoctoral Fellow at Cancer Registry of Norway

public
class
MyParcelable
implements
Parcelable
{

private
int
mData;

!

public
int
describeContents()
{

return
0;

}

!

public
void
writeToParcel(Parcel
out,
int
flags)
{

out.writeInt(mData);

}

!

public
static
final
Parcelable.Creator<MyParcelable>
CREATOR

=
new
Parcelable.Creator<MyParcelable>()
{

public
MyParcelable
createFromParcel(Parcel
in)
{

return
new
MyParcelable(in);

}

!

public
MyParcelable[]
newArray(int
size)
{

return
new
MyParcelable[size];

}

};

private
MyParcelable(Parcel
in)
{

mData
=
in.readInt();

}

}

Postfix Completion
Type expression
ending in a dot
Ctrl + Space
1
2 Choose:

field,
var,
cast,
instanceof,

not
null,
null,
par,
for,
fori,

…3

Postfix Completion
fori
for
notnull

Postfix Completion
Quick typing
Short completions
Remember commands
Not customizable

Live Templates
Type your shortcut keyword
Expand with {Space | Tab | Enter}
1
2
Fill missing parts
3

Live Templates
Create Template Group
or Live Template
1
Editable in Preferences
>
Live
Templates

Live Templates
Fill abbreviation, description and
template code
2
>
Live
Templates

Live Templates
Define applicability scope
3
>
Live
Templates

Live Templates
Use it
4
>
Live
Templates

Live Templates
Templates can be parameterized
2b
>
Live
Templates

Live Templates
Quick typing
Short completions
Remember commands
Customizable (to some extent)

file0..*
Template Structure
Template Folder
root
globals.xml.ftl1
recipe.xml.ftl1
template.xml1
icon.png0..*
file.ftl0..*
Place it under
!
<AndroidStudioPath>/plugins/android/lib/templates

file0..*
Template Structure
Template Folder
root
globals.xml.ftl1
recipe.xml.ftl1
template.xml1
icon.png0..*
file.ftl0..*
Definition of the
template
Place it under
!

file0..*
Template Structure
Template Folder
root
globals.xml.ftl1
recipe.xml.ftl1
template.xml1
icon.png0..*
file.ftl0..*
Global variables for
the code generation
Place it under
!

file0..*
Template Structure
Template Folder
root
globals.xml.ftl1
recipe.xml.ftl1
template.xml1
icon.png0..*
file.ftl0..*
Actions to perform
when template is
selected
Place it under
!

file0..*
Template Structure
Template Folder
root
globals.xml.ftl1
recipe.xml.ftl1
template.xml1
icon.png0..*
file.ftl0..*Icons to represent
the template
Place it under
!

file0..*
Template Structure
Template Folder
root
globals.xml.ftl1
recipe.xml.ftl1
template.xml1
icon.png0..*
file.ftl0..*
Files that just need
to be copied
Place it under
!

file0..*
Template Structure
Template Folder
root
globals.xml.ftl1
recipe.xml.ftl1
template.xml1
icon.png0..*
file.ftl0..*
Files that need to be
filled with data
Place it under
!

template.xml
<template

format="4"

revision="1"

name="Retrofit
Service"

description="Creates
a
new
Retrofit
interface.">

!

<category
value="Everyware"
/>

!
...

!
</template>

template.xml
<parameter

id="className"

name="Interface
Name"

type="string"

constraints="class|unique|nonempty"

default="MyService"
/>
<parameter

id="operationType"

name="Operation
Type"

type="enum"

constraints="nonempty"

default="get">

<option
id="get">GET</option>

<option
id="post">POST</option>

</parameter>

globals.xml.ftl
<?xml
version="1.0"?>

<globals>

<global
id="manifestOut"
value="${manifestDir}"
/>

...

</globals>

globals.xml.ftl
<?xml
version="1.0"?>

<globals>

<global
id="manifestOut"
value="${manifestDir}"
/>

...

</globals>

FreeMarker notation
to access a variable

<?xml
version="1.0"?>

<recipe>

<dependency
mavenUrl="com.squareup.retrofit:retrofit:1.8.0"/>

!
!

<copy
from="res/values/urls.xml"

to=“${resOut}/values/urls.xml"
/>

!
!

<instantiate
from="src/app_package/Service.java.ftl"

to="${srcOut}/${className}.java"
/>

!

<open
file="${srcOut}/${className}.java"
/>

!

</recipe>
recipe.xml.ftl

<?xml
version="1.0"?>

<recipe>

<dependency

!
!

<copy

/>

!
!

<instantiate

/>

!

<open
/>

!

</recipe>
recipe.xml.ftl
Adds a provided dependency to
build.gradle

<?xml
version="1.0"?>

<recipe>

<dependency

!
!

<copy

/>

!
!

<instantiate

/>

!

<open
/>

!

</recipe>
recipe.xml.ftl
Copies a file without
processing

<?xml
version="1.0"?>

<recipe>

<dependency

!
!

<copy

/>

!
!

<instantiate

/>

!

<open
/>

!

</recipe>
recipe.xml.ftl
Generates a file from a template and
the provided parameters

<?xml
version="1.0"?>

<recipe>

<dependency

!
!

<copy

/>

!
!

<instantiate

/>

!

<open
/>

!

</recipe>
recipe.xml.ftl
Opens a file in the IDE

<?xml
version="1.0"?>

<recipe>

<dependency

!
!

<copy

/>

!
!

<instantiate

/>

!

<open
/>

!

</recipe>
recipe.xml.ftl
PRO TIP: Put an open command at the end of your recipe to make sure
everything executed correctly

Service.java.ftl
package
${packageName};

!
<@imports/>

!
public
interface
${className}{

<@multipart/>

<@operation/>

<@methodSignature/>

}
<#macro
imports>

<#if
operationType="get">

import
retrofit.http.GET;

<#else/>

import
retrofit.http.POST;

</#if>

...

</#macro>
<#macro
methodSignature>

public
<@output/>
${methodName}(<@methodParameters/>);

</#macro>

ADT Templates
Generates multiple files, even projects
Customizable
Only for creation
Automatic UI wizard generated
Complex syntax
Diﬀicult to test and verify correctness

apply
plugin:
SimplePlugin

!
class
SimplePlugin
implements
Plugin<Project>
{

void
apply(Project
project)
{

!

println
"Hello
World!"

!

}

}
Gradle Plugin

apply
plugin:
SimplePlugin

!
class
SimplePlugin
implements
Plugin<Project>
{

void
apply(Project
project)
{

!

def
hasApp
=
project.plugins.withType(AppPlugin)

def
hasLib
=
project.plugins.withType(LibraryPlugin)

if
(!hasApp
&&
!hasLib)
{

throw
new
IllegalStateException("'android'
or
'android-‐
library'
plugin
required.")

}

!

}

}
Checking Android plugin dependencies

Adding dependencies
apply
plugin:
SimplePlugin

!
class
SimplePlugin
implements
Plugin<Project>
{

void
apply(Project
project)
{

!

project.dependencies
{

debugCompile
'your-‐dependency'

compile
'your-‐dependency'

}

!

}

}

apply
plugin:
SimplePlugin

!
class
SimplePlugin
implements
Plugin<Project>
{

void
apply(Project
project)
{

!

project.extensions.create('myextension',

SimpleExtension)

!

}

}

!
class
SimpleExtension
{

int
aNumber
=
0

List<String>
aList
=
[]

}
Adding extensions

Adding extensions
apply
plugin:
'com.android.application'

apply
plugin:
SimplePlugin

!
android
{

compileSdkVersion
21

buildToolsVersion
"21.1.2"

!

defaultConfig
{

applicationId
"es.everywaretech.myapplication"

minSdkVersion
15

targetSdkVersion
21

versionCode
1

versionName
"1.0"

}

}

...

myextension{

aNumber
=
42

aList
=
["Hello",
"World"]

}

Iterating through Variants
apply
plugin:
SimplePlugin

!
class
SimplePlugin
implements
Plugin<Project>
{

void
apply(Project
project)
{

!

variants.all
{
variant
-‐>

if
(!variant.buildType.isDebuggable())
{

//
Do
something
with
Debug
variant

}else{

//
Do
something
with
Release
variant

}

}

!

}

}

Creating custom tasks
class
SimpleTask
extends
DefaultTask
{

String
greeting
=
'Hello
World'

!

@TaskAction

def
greet()
{

println
greeting

}

}

!
//
Use
the
default
task

task
hello(type:
SimpleTask)

!
//
Customize
the
task

task
droidcon(type:
SimpleTask)
{

greeting
=
'Hello
Droidcon'

}

Creating custom incremental tasks
class
MyIncrementalTask
extends
DefaultTask
{

@InputDirectory

def
File
inputDir

!

@OutputDirectory

def
File
outputDir

!

@Input

def
inputProperty

!

@TaskAction

void
execute(IncrementalTaskInputs
inputs)
{

if(inputs.incremental){

//
Only
changed
files
will
be
provided

}else{

//
All
files
will
be
provided

}

...

}

}
Warning! Incubating feature

Creating custom incremental tasks
class
MyIncrementalTask
extends
DefaultTask
{

...

!

@TaskAction

void
execute(IncrementalTaskInputs
inputs)
{

...

inputs.outOfDate
{
change
-‐>

//
Do
something

}

!

inputs.removed
{
change
-‐>

//
Do
something

}

}

}
Warning! Incubating feature

Gradle Plugins
Helps with recurring building tasks
Not only for source code, also other
resources
Only available at build time

Using annotations
@Nullable

@Override

public
View
onCreateView(String
name,

@NonNull
Context
context,

@NonNull
AttributeSet
attrs)
{

...

}

Using annotations
@Nullable

@Override

public
View
onCreateView(String
name,

@NonNull
Context
context,

@NonNull
AttributeSet
attrs)
{

...

}

PRO TIP: Use Support Annotations
!
dependencies
{

compile
'com.android.support:support-‐annotations:20.0.0'

}

Defining annotations types
@Retention(Retention.{SOURCE|CLASS|RUNTIME})

@Target(ElementType.{ANNOTATION_TYPE|CONSTRUCTOR|FIELD|

LOCAL_VARIABLE|METHOD|PACKAGE|

PARAMETER|TYPE})

public
@interface
MyAnnotation{

String
value()
default
"some
string";

int
number()
default
0;

}

!
@MyAnnotation("another
string",
number
=
42)

public
class
MyClass{

...

}

Processing annotations
public
interface
Processor{

!

Iterable<?
extends
Completion>
getCompletions(Element
element,

AnnotationMirror
annotation,

ExecutableElement
member,

String
userText);

!

Set<String>
getSupportedAnnotationTypes();

!

Set<String>
getSupportedOptions();

!

SourceVersion
getSupportedSourceVersion();

!

void
init(ProcessingEnvironment
processingEnv);

!

boolean
process(Set<?
extends
TypeElement>
annotations,

RoundEnvironment
roundEnv);

!
}

public
interface
Processor{

!

Iterable<?
extends
Completion>
element,

AnnotationMirror
annotation,

ExecutableElement
member,

String
userText);

!

Set<String>

!

Set<String>

!

SourceVersion

!

void
processingEnv);

!

boolean
process(Set<?
extends
TypeElement>
annotations,

RoundEnvironment
roundEnv);

!
}
Suggestions for the IDE to
complete an annotation

public
interface
Processor{

!

Iterable<?
extends
Completion>
element,

AnnotationMirror
annotation,

ExecutableElement
member,

String
userText);

!

Set<String>

!

Set<String>

!

SourceVersion

!

void
processingEnv);

!

boolean
process(Set<?
extends
TypeElement>
annotations,

RoundEnvironment
roundEnv);

!
}
Annotations that this
Processor is able to handle

public
interface
Processor{

!

Iterable<?
extends
Completion>
element,

AnnotationMirror
annotation,

ExecutableElement
member,

String
userText);

!

Set<String>

!

Set<String>

!

SourceVersion

!

void
processingEnv);

!

boolean
process(Set<?
extends
TypeElement>
annotations,

RoundEnvironment
roundEnv);

!
}
Processor
initialization

public
interface
Processor{

!

Iterable<?
extends
Completion>
element,

AnnotationMirror
annotation,

ExecutableElement
member,

String
userText);

!

Set<String>

!

Set<String>

!

SourceVersion

!

void
processingEnv);

!

boolean
process(Set<?
extends
TypeElement>
annotations,

RoundEnvironment
roundEnv);

!
}
Inspection of the annotations
and code generation

public
interface
ProcessingEnvironment{

Elements
getElementUtils();

!

Filer
getFiler();

!

Locale
getLocale();

!

Messager
getMessager();

!

Map<String,String>
getOptions();

!

SourceVersion
getSourceVersion();

!

Types
getTypeUtils();

}

public
interface

Elements
getElementUtils();

!

Filer
getFiler();

!

Locale
getLocale();

!

Messager
getMessager();

!

Map<String,String>
getOptions();

!

SourceVersion
getSourceVersion();

!

Types
getTypeUtils();

}
Creation of new Files

public
interface

Elements
getElementUtils();

!

Filer
getFiler();

!

Locale
getLocale();

!

Messager
getMessager();

!

Map<String,String>
getOptions();

!

SourceVersion
getSourceVersion();

!

Types
getTypeUtils();

}
Writing warnings and
errors

@AutoService(Processor.class)

public
class
MyProcessor{

!

@Override
public
Set<String>
getSupportedAnnotationTypes(){

return
Collections.singleton(MyAnnotation.class.getName());

}

!

@Override
public
SourceVersion
getSupportedSourceVersion(){

return
SourceVersion.latestSupported();

}

!

@Override
public
boolean
process(Set<?
extends
TypeElement>

annotations,
RoundEnvironment
roundEnv){

!

Set<?
extends
Element>
elements

=
roundEnv.getElementsAnnotatedWith(MyAnnotation.class);

//
Process
elements
and
generate
code

!

return
false;

}

}


public
class
MyProcessor{

!

@Override
public
Set<String>

return

}

!

@Override
public
SourceVersion

return

}

!

@Override
public
boolean
process(Set<?
extends
TypeElement>

annotations,
RoundEnvironment
roundEnv){

!

Set<?
extends
Element>
elements

=

//
Process
elements
and
generate
code

!

return
false;

}

}
PRO TIP: Use com.squareup.JavaPoet
to generate code


public
class
MyProcessor{

!

@Override
public
Set<String>

return

}

!

@Override
public
SourceVersion

return

}

!

@Override
public
boolean
process(Set<?
extends
TypeElement>

annotations,
RoundEnvironment
roundEnv){

!

Set<?
extends
Element>
elements

=

//
Process
elements
and
generate
code

!

return
false;

}

}
Allows other processors to
handle the same annotations


public
class
MyProcessor{

!

@Override
public
Set<String>

return

}

!

@Override
public
SourceVersion

return

}

!

@Override
public
boolean
process(Set<?
extends
TypeElement>

annotations,
RoundEnvironment
roundEnv){

!

Set<?
extends
Element>
elements

=

//
Process
elements
and
generate
code

!

return
false;

}

}
PRO TIP: Use AutoService
to generate META-INF

Generation process
javac
MyProcessor YourProcessor
A.java

javac
A.java
A.class
Generation process

javac
A.java
A.class
B.java
Generation process

javac
A.java
A.class
B.java
B.class
Generation process

javac
A.java
A.class
B.java
B.class
C.java
Generation process

javac
A.java
A.class
B.java
B.class
C.java
C.class
Generation process

Annotation Processors
Java feature, IDE independent
Not only for source code, also other
resources
Expensive if done at runtime
Testable

Extending AnAction
public
class
MyAction
extends
AnAction
{

@Override

public
void
actionPerformed(AnActionEvent
e)
{

!

}

}

Retrieve the selected element
public
class
MyAction
extends
AnAction
{

@Override

public
void
e)
{

!

PsiFile
psiFile
=
e.getData(LangDataKeys.PSI_FILE);

Editor
editor
=
e.getData(PlatformDataKeys.EDITOR);

!

if
(psiFile
==
null
||
editor
==
null)
{

return;

}

!

int
offset
=
editor.getCaretModel().getOffset();

PsiElement
element
=
psiFile.findElementAt(offset);

!

}

}

Retrieve the selected class
public
class
MyAction
extends
AnAction
{

@Override

public
void
e)
{

!

PsiFile
psiFile
=
e.getData(LangDataKeys.PSI_FILE);

Editor
editor
=
e.getData(PlatformDataKeys.EDITOR);

!

if
(psiFile
==
null
||
editor
==
null)
{

return;

}

!

int
offset
=
editor.getCaretModel().getOffset();

PsiElement
element
=
psiFile.findElementAt(offset);

!

PsiClass
psiClass
=
PsiTreeUtil.getParentOfType(element,

PsiClass.class);

!

}

}

Generate code
public
class
MyAction
extends
AnAction
{

@Override

public
void
e)
{

!

...

!

new
WriteCommandAction.Simple(psiClass.getProject(),

psiClass.getContainingFile())
{

@Override

protected
void
run()
throws
Throwable
{

generateCode(psiClass);

}

}.execute();

}

}

Generate code
public
void
generateCode(PsiClass
psiClass){

PsiElementFactory
elementFactory
=

JavaPsiFacade.getElementFactory(psiClass.getProject());

!

PsiMethod
myMethod
=

elementFactory.createMethodFromText(methodCode,
psiClass);

!

PsiField
myField
=

elementFactory.createFieldFromText(fieldCode,
psiClass);

!

...

}

Generate code
public
void
generateCode(PsiClass
psiClass){

...

!

JavaCodeStyleManager
styleManager
=

JavaCodeStyleManager.getInstance(psiClass.getProject());

!

styleManager.shortenClassReferences(

psiClass.addBefore(myMethod,
psiClass.getLastChild()));

!

styleManager.shortenClassReferences(

psiClass.addBefore(myField,
psiClass.getLastChild()));

}

Register action
<idea-‐plugin
version="4">

<id>com.example.myplugin</id>

<name>Droidcon
Plugin</name>

<version>1.0</version>

<vendor
email="tomas@everywaretech.es"

url="http://www.everywaretech.es">

Tomás
Ruiz-‐López

</vendor>

!

<actions>

<action
id="myplugin"

class="es.everywaretech.myplugin"

text="MyPlugin"

description="Generates
Boilerplate
Code">

!

<add-‐to-‐group
group-‐id="MainMenu"
anchor="last"/>

</action>

</actions>

</idea-‐plugin>

plugin.xml

Register action
<idea-‐plugin
version="4">

<id>com.example.myplugin</id>

<name>Droidcon
Plugin</name>

<version>1.0</version>

<vendor
email="tomas@everywaretech.es"

url="http://www.everywaretech.es">

Tomás
Ruiz-‐López

</vendor>

!

<actions>

<action
id="myplugin"

class="es.everywaretech.myplugin"

text="MyPlugin"

description="Generates
Boilerplate
Code">

!

<add-‐to-‐group
group-‐id="MainMenu"
anchor="last"/>

</action>

</actions>

</idea-‐plugin>

See
com.intellij.openapi.actionSystem.ActionPlaces

for more group ids
plugin.xml

IDE Plugins
More flexible
Fine and coarse grained code generation
More complex to develop
Only for IntelliJ or Android Studio

About ADT Templates
Oﬀicial documentation
https://android.googlesource.com/platform/sdk/+/refs/heads/master/templates/docs/index.html
About Gradle Plugins
Writing Custom Plugins
https://gradle.org/docs/current/userguide/custom_plugins.html
!
Lessons learned from our first Gradle plugin for Android,
Victor
https://trello.engineering/victor/
!
Hugo
https://github.com/JakeWharton/hugo

About Annotation Processors
Annotation Processing Boilerplate Destruction
https://speakerdeck.com/jakewharton/annotation-processing-boilerplate-destruction-droidcon-nyc-2014
About IntelliJ Plugins
Getting Started with Plugin Development
https://confluence.jetbrains.com/display/IDEADEV/Getting+Started+with+Plugin+Development
!

Thanks!
QUESTIONS?
Tomás Ruiz López
Droidcon Spain 2015@tomasruizlopez

Weapons for Boilerplate Destruction

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