Groovy Goodness Notebook

About Me

Introduction

1. Code samples

Syntax

1. Default Imports
2. Semicolons are Optional
3. Optional return Keyword
4. Automatic Return Value Casting
5. Static Imports
6. Optional Parenthesis
7. Check for Object Equality
8. Using def to Define a Variable
9. Using Lists and Maps As Constructors
10. Parameters with Default Values
11. Named Parameters are Converted to Map
12. Use a Map as Interface Implementation
13. MultiMethods or Multiple Dispatch
14. Multiple Overloaded Operator Methods for Nice API
15. Operator Overloading in Reverse
16. Exception Handling
17. The With Method
18. Easy Object Creation With Tap Method
19. The Switch Statement
20. Use Map in Switch Statement
21. Using The Switch Expression
22. Tell the Groovy Truth
23. We Can Handle the Truth
24. Groovy Truth for Simple Type Arrays
25. Boolean Implications
26. The as Keyword
27. Define Your Own Type Conversion
28. Using Project Coin Features Also With Older Java Versions
29. Getting and Setting Properties
30. GroovyBeans the Simpler JavaBeans
31. Powerful Assert
32. Multiple Assignments
33. Multiple Assignments Revisited
34. Turn Methods into Closures
35. Use Keywords as Method Names
36. Chaining Traits
37. Implementing Traits at Runtime
38. Using Implicit call() Method
39. Groovy Mystic Expressions
40. Invoke Methods Dynamically
41. Create Class Instance Dynamically
42. Know More About a Class
43. Getting Information About Objects
44. Get Hints About Missing Methods or Properties
45. Executing String or List
46. Run Code at a Specified Time
47. Using AntBuilder
48. Add a ShutdownHook
49. Add a ShutdownHook
50. Defining Public Accessible Constant Fields
51. Direct Field Access In (Super) Classes
52. Use Optional In Conditional Context
53. Check Item Is Not In A Collection With !in

Operators

1. Safe Navigation to Avoid NullPointerException
2. The Elvis Operator ?:
3. The Elvis Assignment Operator
4. The Spaceship Operator
5. The Spread-Dot Operator
6. The Spread Operator
7. Are You In? (Membership Operator)
8. Is Object in Class Hierarchy
9. Check Object Instances Are The Same With === Operator
10. Using !instanceof Operator
11. Safe Index Based Access For Lists, Arrays and Maps
12. Using The Call Operator ()

Numbers

1. BigDecimal
2. Round and Truncate Decimal Values
3. Truncate And Round BigDecimal Values
4. Integer Divisions
5. Make a Number Absolute
6. Raising the Power of Numbers

Strings

1. Turn Methods into Closures
2. New Dollar Slashy Strings
3. Get to Know More About a GString
4. Check if String is a Number
5. What Character Are You?
6. Access Strings with Subscript Operator
7. Capitalize Strings
8. Uncapitalize Strings
9. Base64 Encoding
10. Check if a String Only Contains Whitespaces
11. Convert String to Boolean
12. Padding Strings
13. Working with Lines in Strings
14. Getting Parts Of A String Enclosed By Strings
15. Using the replaceAll Methods from String
16. Replace Characters in a String with CollectReplacements
17. Text Translation
18. Remove Parts of a String
19. Remove Part of String With Regular Expression Pattern
20. Taking Or Dropping Number Of Characters From A String
21. Splitting Strings
22. Get Unique Characters in a String
23. Partial Matches
24. Transform String into Enum
25. String Continuation
26. Strip Leading Spaces from Lines
27. Strip Leading Spaces from Lines with Margin
28. Formatted Strings with sprintf
29. Expand or Unexpand Space or Tab Delimited Text
30. Normalize and Denormalize Linefeeds and Carriage Returns
31. Base64 URL and Filename Safe Encoding
32. Calculate MD5 And SHA Hash Values
33. Converting Byte Array to Hex String
34. GString as Writable
35. Closure as Writable

Regular Expressions

1. Using Regular Expression Pattern Class
2. Matchers for Regular Expressions

Dates

1. Working with Dates
2. Setting Date and Calendar Values with Subscript Operators
3. Convert Date to java.sql.Timestamp
4. Convert Date to Calendar
5. Format Dates with TimeZone
6. Parse Date.toString() Value
7. Use the set Method to Define a Date or Calendar Value
8. Create New Date from Old Date with Updates
9. Create New Date or Calendar from Existing and Set Property Value
10. Clear Time Portion of a Date
11. Date and Time Durations and the TimeCategory
12. Loop Through Date and Calendar Ranges
13. Using Subscript Operator With Multiple Fields On Date Related Objects

List, Ranges and Arrays

1. Create Elements in Collection Definition
2. Finding Data in Collections
3. Find First Non-Null Result From a Closure
4. Find Non-Null Results After Transformation in a Collection
5. Find Elements Matching Groovy Truth
6. Removing Elements From a Collection
7. Use Ranges as Subscript Operators
8. Use Strings as Subscript Operator
9. Using the Subscript Operator on Iterators
10. Use Range By Method To Set Steps Between Numbers
11. Closed And Open Ranges
12. Using String Values In Ranges
13. Looping in Different Ways
14. Keep Your Values in Ranges
15. Getting the Tail of a List
16. Getting Head And Tail From an Array of Objects
17. Getting All Init And Tail Values Recursively
18. Getting the First and Last Element of an Iterable
19. Getting All But the Last Element in a Collection with Init Method
20. Take and Drop Items from a List
21. Drop or Take Elements with Condition
22. Take Or Drop Last Items From a Collection
23. Getting the Indices of a Collection
24. Combine Elements Iterable with Index
25. Pop And Push Items In a List
26. Remove Last Item From List Using RemoveLast Method (And Pop/Push Methods Reimplemented)
27. Apply Method to All Elements in a List
28. Apply Closure to All Element in a Collection with collect
29. Transform Elements While Flattening
30. Use Collect with Initial Collection Value
31. Transform Collection to a Map with collectEntries
32. Transform Items into a Collection with collectMany
33. Collect on Nested Collections
34. Recursively Collect Elements
35. Join Elements to a String
36. Using the Inject Method
37. Using the GroupBy Method
38. GroupBy with Multiple Closures
39. Removing Duplicate Elements in a Collection
40. Sort or Remove Duplicates without Changing the Original Collection
41. New Methods to Sort and Remove Duplicates From Collection
42. Using the OrderBy Comparator
43. Get Row Number In GINQ Result Set
44. GroovyCollections Utility Class
45. Splitting with Closures
46. Intersect Collections
47. Collate a List into Sub-lists
48. Getting All Subsequences of a List
49. Looping Through Each Permutation in a Collection
50. Counting the Items in a List
51. Count Occurrences in a Collection or Map
52. Getting the Sum of Items in a Collection
53. Revisited Getting the Sum of Items in a Collection
54. Sum the Values in a Object Array
55. Calculate Average For Collection
56. Represent a List as String
57. Create a List with Default Values
58. Add Items to a List at Specified Position
59. Working with Arrays
60. See if List and Object Array are Equal
61. Convert Collection to Set with Only Unique Elements
62. See if Sets are Equal
63. Immutable Collections
64. Observable Map and List
65. Enhancements for Iterable Implementations
66. Swapping Elements in a List
67. Intersect Collections With Custom Comparator
68. Java 8 Stream Enhancements
69. Unmodifiable Collections
70. Shuffle List or Array

Maps

1. Check if Maps are Equal
2. Sorting a Map
3. Turn a List into a Map
4. Complex Keys in Maps
5. Use inject Method on a Map
6. Intersect Maps
7. Subtracting Map Entries
8. Process Map Entries in Reverse
9. Getting a Submap from a Map
10. Grouping Map Elements
11. Get Value from Map or a Default Value
12. Map with Default Values
13. Determine Min and Max Entries in a Map
14. Represent Map As String
15. Turn A Map Or List As String To Map Or List

Closures

1. Passing Closures to Methods
2. Closure Arguments
3. Identity Closure
4. Add Some Curry for Taste
5. New Ways to Curry
6. Lambda Default Parameter Value
7. Implicit Closure Coercion
8. Return Closure From Another Closure or Method
9. Chain Closures Together with Closure Composition
10. Recursion with Closure Trampoline Capability
11. Cache Closure Results with Memoization
12. Info About Closure Parameters
13. Setting a Closure's Delegate
14. Invoke Anonymous Closure
15. Implicit Method doCall in Closure
16. Closure as a Class
17. Use Closures as Java Lambda Expressions
18. Use Constructor as Method Pointer

SQL

1. Groovy SQL
2. Groovy SQL DataSet
3. Using Named (Ordinal) Parameters with Groovy SQL
4. Access ResultSetMetaData with Groovy SQL
5. Paging Support in Groovy SQL
6. Use Expanded Variables in SQL GString Query

Files, Readers, Writers and URLs

1. Working with Files
2. Working on Files or Directories (or Both) with FileType
3. Finding Files with FileNameFinder
4. Delete Non-empty Directory Recursively with File
5. Traversing a Directory
6. Creating Files And Directories With Nice DSL Using FileTreeBuilder
7. Calculating Directory Size
8. Extra Methods for NIO Path
9. WithReader and withWriter
10. Transforming Reader Input to Writer Output
11. Append Values to Appendable Objects
12. Apply Read and Write Locking
13. Reading URL Content
14. Use Connection Parameters to Get Text From URL
15. Make Sure Closeable Objects Are Closed Using withCloseable Method

XML and JSON

1. Pretty Print XML
2. Creating XML with MarkupBuilder
3. Refactor XML Creation with StreamingMarkupBuilder
4. Reading XML
5. Type Conversion Using GPathResult When Reading XML
6. Change XML Structure
7. Preorder And Postorder Tree Traversal
8. Getting Groovy with DOM
9. Nested Templates with MarkupTemplateEngine
10. Use Custom Template Class with MarkupTemplateEngine
11. Using Layouts with MarkupTemplateEngine
12. Parse JSON with JsonSlurper
13. Relax... Groovy Will Parse Your Wicked JSON
14. Build JSON with JsonBuilder and Pretty Print JSON Text
15. Creating Root JSON Array With JsonBuilder
16. Streaming JSON with StreamingJsonBuilder
17. Customizing JSON Output
18. Create YAML With YamlBuilder
19. Parse YAML With YamlSlurper

AST transformations

1. Newify to Create New Instances
2. Create a Singleton Class
3. Inject Logging Using Annotations
4. Customise Log AST Annotations
5. Easy toString Creation for Our Classes
6. Customize ToString Creation
7. Tuple Constructor Creation
8. Add Map Constructor With Annotation
9. Generate equals and hashcode Methods with EqualsAndHashCode Annotation
10. Inherit Constructors From Parent Classes
11. Canonical Annotation to Create Mutable Class
12. Make Class Cloneable With @AutoClone
13. Combining Annotations with AnnotationCollector
14. Change Scope Script Variable with Field Annotation
15. Add Java-style Listener Support with ListenerList Annotation
16. Lazy Initialization of Properties
17. Making a Class Immutable
18. Create CopyWith Method with Immutable Annotation
19. Synchronized Annotation for Synchronizing Methods
20. Create Indexed Property Getter and Setter Methods
21. Bound and Constrained Properties in GroovyBeans
22. Delegate to Simplify Code
23. Choose Which Delegated Methods to Use
24. Creating Extra Method Supporting Named Arguments Using @NamedVariant Annotation
25. Cache Methods Invocations with Memoize Annotation
26. Using Package Scoped Methods, Fields and Classes
27. Use Builder AST Transformation for Fluent API
28. Using Builder to Create Fluent API for Other Classes
29. @Builder Definition with Extra Type Checks
30. More Efficient Tail Recursion With TailRecursive Annotation
31. Use Sortable Annotation to Make Classes Comparable
32. Implement Interface And Abstract Methods Automatically

Metaprogramming

1. Create a Singleton Class
2. Use a Category and Get a Return Value
3. Mixin Functionality to Classes
4. Apply Mixin to Object Instances
5. Add Methods Dynamically to Classes with ExpandoMetaClass
6. Create Dynamic Methods
7. A Bit of metaClass DSL
8. Adding or Overriding Methods with ExpandoMetaClass
9. Override getProperty Method with Dynamic Groovy
10. Implementing MetaClass Methods with Same Name but Different Arguments
11. Add Static Methods with MetaClass to Classes
12. Override and Use Old Implementation with Dynamic Methods
13. Add Methods to Interfaces with ExpandoMetaClass
14. Expando as Dynamic Bean
15. Check If Method or Property is Available
16. Intercept Methods with Interceptors
17. Magic Package to Add Custom MetaClass
18. Adding Extra Methods Using Extension Modules

DSL and Builder Support

1. Building Object Graphs
2. Create Simple Builders with Closures
3. Solve Naming Conflicts with Builders
4. Building a GUI with SwingBuilder
5. Command Chain Expressions for Fluid DSLs
6. Store Closures in Script Binding
7. Add Imports Transparently to Scripts with ImportCustomizer
8. Add AST Transformations Transparently to Scripts
9. Create Our Own Script Class
10. Set Script Class with BaseScript Annotation
11. BaseScript with Abstract Run Script Method
12. Set Delegating Class for Script
13. Customize Log Variable Name with Log AST Annotations
14. Define Compilation Customizers With Builder Syntax
15. Restricting Script Syntax With SecureASTCustomizer

Scripts

1. Using Groovy on the Command-Line
2. Default Groovy Script File Extensions
3. Variable Scope in Scripts
4. Grab That Dependency
5. See More Info About Downloading With Grape
6. Configuring Grape to Use Classloader
7. Use GrabResolver for Custom Repositories
8. Resolve Module Location with Grape
9. Change Directory For Saving Dependencies Grape
10. Exclude Transitive Dependencies With Grape
11. Running Groovy Scripts in Java with GroovyClassLoader
12. Simple Evaluation of Groovy Expressions in Java
13. Compiled Groovy Script is a Java Class
14. ServerSocket Scripts
15. Run Remote Scripts via URL
16. Running Scripts from a JAR Archive
17. Redirecting Print Methods In Scripts
18. Customize Groovy Console Visual Output
19. Using Groovy for Git Hooks

Testing

1. Running a Unit Test
2. Testing for Expected Exceptions
3. Create Stubs for Testing

IDE

1. IntelliJ IDEA Intentions For String Values
2. Turn Map Into Class With IntelliJ IDEA
3. Turn Method Parameters Into Named Map Arguments With IntelliJ IDEA
4. IntelliJ IDEA Formatting Of Closure Chains
5. Download Grab Dependencies In IntelliJ IDEA

Miscellaneous

1. Inspect Method Returns Nicely Formatted Object Values
2. Interrupted Sleeping
3. Using Tuples
4. Tuples With Up To 9 Items
5. Using Tuples
6. Where Is My Class?
7. Parsing Commandline Arguments with CliBuilder
8. Get Properties from ReleaseInfo
9. Using ConfigSlurper with Configuration Scripts
10. Extend ConfigSlurper with Custom Environments Sections
11. Check Configuration Property Is Set In ConfigObject
12. Reading TOML Configuration
13. Creating TOML Configuration With TomlBuilder
14. Using Macros For Getting String Representation Of Variables
15. Using Macros For Getting More Information About Variables
16. Using the Template Engines
17. Groovlets as Lightweight Servlets
18. Access XML-RPC API
19. Customise Groovydoc Output With Gradle
20. Customising The Groovy Compiler
21. Using the ServletCategory
22. Using GroovyMBeans for Easy JMX
23. Share Data in Concurrent Environment with Dataflow Variables