Google Guava - Core libraries for Java & Android

Talk at GDG DevFest Barcelona 2013.

The Guava project contains several of Google's core libraries that we rely on in our Java-based projects: collections, caching, primitives support, concurrency libraries, common annotations, string processing, I/O, and so forth.

Transcript

1. Google Guava Core libraries for Java & Android @jordi9 11 / oct / 2013
2. ...shameless self-promotion bro!
3. Write less code
4. Write cleaner code
5. Write more readable code
6. The “wheel”
7. com.google.guava:guava:15.0
8. Basics
9. Basics Avoid using null
10. Basics: Avoid using null “Null sucks” Doug Lea - JCP, OpenJDK
11. Basics: Avoid using null “I call it my billion-dollar mistake” Sir C.A.R. Hoare - Inventor of null
12. Basics: Avoid using null @Google 95% of collections weren’t supposed to have null values.
13. map = {Foo: bar, null, Baz: qux} Basics: Avoid using null
14. map = {Foo: bar, null, Baz: qux} map.get(“Foo”); Basics: Avoid using null
15. map = {Foo: bar, null, Baz: qux} map.get(“Foo”); // returns Foo Basics: Avoid using null
16. map = {Foo: bar, null, Baz: qux} map.get(“Foo”); map.get(“quux”); Basics: Avoid using null
17. map = {Foo: bar, null, Baz: qux} map.get(“Foo”); map.get(“quux”); // returns null Basics: Avoid using null
18. map = {Foo: bar, null, Baz: qux} map.get(“Foo”); map.get(“quux”); map.get(null); Basics: Avoid using null
19. map = {Foo: bar, null, Baz: qux} map.get(“Foo”); map.get(“quux”); map.get(null); // returns null Basics: Avoid using null
20. map = {Foo: bar, null, Baz: qux} map.get(“Foo”); map.get(“quux”); // returns null map.get(null); // returns null Basics: Avoid using null
21. map = {Foo: bar, null, Baz: qux} map.get(“Foo”); map.get(“quux”); // returns null map.get(null); // returns null // Null to indicate absence // vs null value Basics: Avoid using null
22. Optional<T> Basics: Avoid using null
23. Optional<T> Optional<String> foo = Optional.of(“foo”) Basics: Avoid using null
24. Optional<T> Optional<String> foo = Optional.of(“foo”) foo.isPresent(); // returns true Basics: Avoid using null
25. Optional<T> Optional<String> foo = Optional.of(“foo”) foo.isPresent(); foo.get(); // returns “foo” Basics: Avoid using null
26. Optional.of(foo); // not nullable Goodies! RTFM, I mean javadoc
27. Optional.of(foo); Optional.absent(); Goodies! javadoc
28. Optional.of(foo); Optional.absent(); Optional.fromNullable(legacyCode); Goodies! javadoc
29. Optional.of(foo); Optional.absent(); Optional.fromNullable(legacyCode); foo.get(); // may return “foo” Goodies! javadoc
30. Optional.of(foo); Optional.absent(); Optional.fromNullable(legacyCode); foo.get(); foo.or(“bar”); // return “bar” if foo is absent Goodies! javadoc
31. Optional.of(foo); Optional.absent(); Optional.fromNullable(legacyCode); foo.get(); foo.or(“bar”); foo.orNull(); // Deal with code that need nulls, duh Goodies! javadoc
32. Optional<T> is IDIOT-PROOF-NESS Bottom line
33. Basics Preconditions
34. if (seats <= 0) { throw new IllegalArgumentException(“Seats must be positive, but was ” + seats); } Basics: Preconditions
35. if (seats <= 0) { throw new IllegalArgumentException(“Seats must be positive, but was ” + seats); } checkArgument(seats > 0, “Seats must be positive, but was %s”, seats); Basics: Preconditions
36. // Always use static import import static com.google.common.base.Preconditions.checkArgument; checkArgument(seats > 0, “Seats must be positive, but was %s”, seats); Basics: Preconditions
37. import static com.google.common.base.Preconditions.checkArgument; // Check what you expect to be true checkArgument(seats > 0, “Seats must be positive, but was %s”, seats); Basics: Preconditions
38. import static com.google.common.base.Preconditions.checkArgument; // “%s” specifier is recognized as a placeholder in // these messages (the only one) checkArgument(seats > 0, “Seats must be positive, but was %s”, seats); Basics: Preconditions
39. void execute(Job job) { // serious business } Basics: Preconditions
40. void execute(Job job) { checkNotNull(job, “Job can’t be null”); // serious business } // checkNotNull() throws NullPointerException Basics: Preconditions
41. void execute(Job job) { checkNotNull(job, “Job can’t be null”); checkArgument(!job.started(), “Job already started”); // serious business } // checkArgument() throws IllegalArgumentException // checkNotNull() throws NullPointerException Basics: Preconditions
42. void execute(Job job) { checkNotNull(job, “Job can’t be null”); checkArgument(!job.started(), “Job already started”); // serious business checkState(seatsAvailabe <= totalSeats, “You’ve sold more seats than available! This should never happen. %s/%s”, seatsAvailable, totalSeats); } // checkState() throws IllegalStateException // checkArgument() throws IllegalArgumentException // checkNotNull() throws NullPointerException Basics: Preconditions
43. this.foo = checkNotNull(foo); // inline assig Goodies! javadoc
44. this.foo = checkNotNull(foo); // list, string or array checks checkElementIndex(index, size); checkPositionIndex(index, size); checkPositionIndexes(start, end, size); Goodies! javadoc
45. Preconditions will save your ass Bottom line
46. Basics Objects
47. @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (obj == null || obj.getClass() != this.getClass()) { return false; } Person guest = (Person) obj; return id == guest.id && (firstName == guest.firstName || (firstName != null && firstName.equals(guest.getFirstName()))) && (lastName == guest.lastName || (lastName != null && lastName.equals(guest.getLastName()))); } Basics: Objects
48. @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (obj == null || obj.getClass() != this.getClass()) { return false; } Person guest = (Person) obj; return id == guest.id && (firstName == guest.firstName || (firstName != null && firstName.equals(guest.getFirstName()))) && (lastName == guest.lastName || (lastName != null && lastName.equals(guest.getLastName()))); } Basics: Objects F
49. @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (obj == null || obj.getClass() != this.getClass()) { return false; } Person guest = (Person) obj; return id == guest.id && (firstName == guest.firstName || (firstName != null && firstName.equals(guest.getFirstName()))) && (lastName == guest.lastName || (lastName != null && lastName.equals(guest.getLastName()))); } Basics: Objects FM
50. @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (obj == null || obj.getClass() != this.getClass()) { return false; } Person guest = (Person) obj; return id == guest.id && (firstName == guest.firstName || (firstName != null && firstName.equals(guest.getFirstName()))) && (lastName == guest.lastName || (lastName != null && lastName.equals(guest.getLastName()))); } Basics: Objects FML
51. @Override public boolean equals(Object obj) { if (obj instanceof Person) { Person that = (Person) obj; return Objects.equal(firstName, that.firstName) && Objects.equal(lastName, that.lastName); } else { return false; } } Basics: Objects
52. @Override public boolean equals(Object obj) { if (obj instanceof Person) { Person that = (Person) obj; return Objects.equal(firstName, that.firstName) // null safe! && Objects.equal(lastName, that.lastName); // null safe x2! } else { return false; } } Basics: Objects
53. @Override public boolean equals(Object obj) { if (obj instanceof Person) { Person that = (Person) obj; return Objects.equal(firstName, that.firstName) && Objects.equal(lastName, that.lastName); } else { return false; } } // JDK 1.7 introduced equivalent Objects.equals() method. Basics: Objects
54. @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + ((firstName == null) ? 0 : firstName.hashCode()); result = prime * result + id; result = prime * result + ((lastName == null) ? 0 : lastName.hashCode()); return result; } Basics: Objects
55. @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + ((firstName == null) ? 0 : firstName.hashCode()); result = prime * result + id; result = prime * result + ((lastName == null) ? 0 : lastName.hashCode()); return result; } // oh, grumpy cat! Basics: Objects
56. @Override public int hashCode() { return Objects.hashCode(firstName, lastName); } Basics: Objects
57. @Override public int hashCode() { // sensible, order-sensitive hash return Objects.hashCode(firstName, lastName); } Basics: Objects
58. @Override public int hashCode() { return Objects.hashCode(firstName, lastName); } // JDK 1.7 introduced equivalent Objects.hash() method. Basics: Objects
59. @Override public String toString() { } Basics: Objects
60. @Override public String toString() { } Basics: Objects
61. @Override public String toString() { return Objects.toStringHelper(this) .add("firstName", firstName) .add("lastName", lastName) .add("catName", catName) .toString(); } Basics: Objects
62. @Override public String toString() { return Objects.toStringHelper(this) .add("firstName", firstName) .add("lastName", lastName) .add("catName", catName) .toString(); } // returns Person{firstName=Solid, lastName=Snake, catName=null} Basics: Objects
63. @Override public String toString() { return Objects.toStringHelper(this) .add("firstName", firstName) .add("lastName", lastName) .add("catName", catName) .omitNullValues() .toString(); } Basics: Objects
64. @Override public String toString() { return Objects.toStringHelper(this) .add("firstName", firstName) .add("lastName", lastName) .add("catName", catName) .omitNullValues() .toString(); } // returns Person{firstName=Solid, lastName=Snake} Basics: Objects
65. IntelliJ IDEA support for ToStringHelper() Generate toString() > Template Objects.ToStringHelper (Guava) Goodies! javadoc
66. So common stuff should ring a bell Bottom line
67. Basics Ordering
68. Comparator<Person> byDescAgeName = new Comparator<Person>() { public int compare(Person p1, Person p2) { int result = p2.getAge() - p1.getAge(); // ugh! return (result == 0) ? p1.compareTo(p2) : result; } }; // Ok, it’s not that bad -- But it’s pretty hard to get Basics: Ordering
69. Comparator<Person> byDescAgeName = new Comparator<Person>() { public int compare(Person p1, Person p2) { int result = p2.getAge() - p1.getAge(); // ugh! return (result == 0) ? p1.compareTo(p2) : result; } }; // Ok, it’s not that bad -- But it’s pretty hard to get // We’re lucky ints and Person are Comparable, otherwise you’ll // have to implement it Basics: Ordering
70. Comparator<Person> byDescAgeName = new Comparator<Person>() { public int compare(Person p1, Person p2) { return ComparisonChain.start() .compare(p2.getAge(), p1.getAge()) .compare(p1, p2) .result(); } }; Basics: Ordering
71. Comparator<Person> byDescAgeName = new Comparator<Person>() { public int compare(Person p1, Person p2) { return ComparisonChain.start() .compare(p2.getAge(), p1.getAge()) .compare(p1, p2) .result(); } }; // Short-circuits: If one comparison is not equals, stop and return Basics: Ordering
72. Comparator<Person> byDescAgeName = Ordering.natural() .reverse() .onResultOf(new Function<Person, Integer>() { public Integer apply(Person person) { return person.getAge(); }}) .compound(Ordering.natural()); } }; Basics: Ordering
73. Comparator<Person> byDescAgeName = Ordering.natural() .reverse() .onResultOf(new Function<Person, Integer>() { public Integer apply(Person person) { return person.getAge(); }}) .compound(Ordering.natural()); } }; // Read backwards Basics: Ordering
74. Ordering is an “enriched” Comparator. It’s fuuuuuuuun! Goodies! javadoc
75. Ordering is an “enriched” Comparator. It’s fluent. Goodies! javadoc
76. Ordering is an “enriched” Comparator. It’s fluent. // Subclass Ordering and implement compare(T,T) Ordering<Throwable> ORDER_BY_CLASS_NAME = (left, right) -> { return Ordering.usingToString() .compare(left.getClass(), right.getClass()); }; Goodies! javadoc
77. Ordering is an “enriched” Comparator. It’s fluent. // Subclass Ordering and implement compare(T,T) Ordering<Throwable> ORDER_BY_CLASS_NAME = (left, right) -> { return Ordering.usingToString() .compare(left.getClass(), right.getClass()); }; // Or create one Ordering.from(comparator); Ordering.natural(); Goodies! javadoc
78. Ordering is an “enriched” Comparator. It’s fluent. // Subclass Ordering and implement compare(T,T) Ordering<Throwable> ORDER_BY_CLASS_NAME = (left, right) -> { return Ordering.usingToString() .compare(left.getClass(), right.getClass()); }; // Or create one Ordering.from(comparator); Ordering.natural(); // And chain! ORDER_BY_CLASS_NAME.nullsFirst().reverse().compound(comparator); Goodies! javadoc
79. There’s a better way than Comparator Bottom line
80. Basics Throwables
81. void oneLineOfCode() { DatagramPacket packet = new DatagramPacket(data, length); } Basics: Throwables
82. void oneLineOfCode() { DatagramPacket packet = new DatagramPacket(data, length); } // Compile error, throws IOException Basics: Throwables
83. void oneLineOfCode() throws IOException { DatagramPacket packet = new DatagramPacket(data, length); } void someLayer() { oneLineOfCode(); } Basics: Throwables
84. void oneLineOfCode() throws IOException { DatagramPacket packet = new DatagramPacket(data, length); } void someLayer() { oneLineOfCode(); } // Compile error, throws IOException Basics: Throwables
85. void oneLineOfCode() throws IOException { DatagramPacket packet = new DatagramPacket(data, length); } void someLayer() throws IOException { oneLineOfCode(); } void someCoolAbstraction() { someLayer(); } Basics: Throwables
86. void oneLineOfCode() throws IOException { DatagramPacket packet = new DatagramPacket(data, length); } void someLayer() throws IOException { oneLineOfCode(); } void someCoolAbstraction() { someLayer(); } // Compile error, AGAIN Basics: Throwables
87. void oneLineOfCode() throws IOException { DatagramPacket packet = new DatagramPacket(data, length); } void someLayer() throws IOException { oneLineOfCode(); } void someCoolAbstraction() throws IOException { someLayer(); } Basics: Throwables
88. void oneLineOfCode() throws IOException { DatagramPacket packet = new DatagramPacket(data, address); } void someLayer() throws IOException { oneLineOfCode(); } void someCoolAbstraction() throws IOException { someLayer(); } // c’mon... Basics: Throwables
89. void oneLineOfCode() { // Take 2 DatagramPacket packet = new DatagramPacket(data, length); } Basics: Throwables
90. void oneLineOfCode() { try { DatagramPacket packet = new DatagramPacket(data, length); } catch (IOException e) { } } Basics: Throwables
91. void oneLineOfCode() { try { DatagramPacket packet = new DatagramPacket(data, length); } catch (IOException e) { // Really? Swallow? Sure? At least explain why! } } Basics: Throwables
92. void oneLineOfCode() { try { DatagramPacket packet = new DatagramPacket(data, length); } catch (IOException e) { SendMeAnEmail.error(); } } Basics: Throwables
93. void oneLineOfCode() { try { DatagramPacket packet = new DatagramPacket(data, length); } catch (IOException e) { SendMeAnEmail.error(); Oh.theLogger().fatal(“WHY Y U FATAL NOW?”); } } Basics: Throwables
94. void oneLineOfCode() { try { DatagramPacket packet = new DatagramPacket(data, length); } catch (IOException e) { SendMeAnEmail.error(); Oh.theLogger().fatal(“WHY Y U FATAL NOW?”); // repeat for every catch block } } Basics: Throwables
95. void oneLineOfCode() { try { DatagramPacket packet = new DatagramPacket(data, length); } catch (IOException e) { SendMeAnEmail.error(); Oh.theLogger().fatal(“WHY Y U FATAL NOW?”); // repeat for every catch block // AGAIN AND AGAIN } } Basics: Throwables
96. void oneLineOfCode() { try { DatagramPacket packet = new DatagramPacket(data, address); } catch (IOException e) { SendMeAnEmail.error(); Oh.theLogger().fatal(“WHY Y U FATAL NOW?”); // repeat for every catch block // AGAIN AND AGAIN } } Basics: Throwables
97. void oneLineOfCode() { // Take 3 DatagramPacket packet = new DatagramPacket(data, length); } Basics: Throwables
98. void oneLineOfCode() { try { DatagramPacket packet = new DatagramPacket(data, length); } catch (IOException e) { handle(e); } } // We know what to do with this Exception, like recover Basics: Throwables
99. void oneLineOfCode() { try { DatagramPacket packet = new DatagramPacket(data, length); } catch (IOException e) { throw new MyException(e); } } // Translate the Exception to another one more suitable Basics: Throwables
100. void oneLineOfCode() { try { DatagramPacket packet = new DatagramPacket(data, length); } catch (IOException e) { throw Throwables.propagate(e); } } // Propagates the throwable as-is if it is a RuntimeException or // an Error, or wraps it in a RuntimeException and throws it // otherwise. Basics: Throwables
101. // more forms propagateIfInstanceOf(throwable,exceptionClass); Goodies… or gotcha’s! javadoc
102. // more forms propagateIfInstanceOf(throwable,exceptionClass); propagateIfPossible(throwable); // Only if RuntimeException or Error Goodies… or gotcha’s! javadoc
103. // more forms propagateIfInstanceOf(throwable,exceptionClass); propagateIfPossible(throwable); propagateIfPossible(throwable, exceptionClass); Goodies… or gotcha’s! javadoc
104. // more forms propagateIfInstanceOf(throwable,exceptionClass); propagateIfPossible(throwable); propagateIfPossible(throwable, exceptionClass); General practice: Convert checked exceptions to unchecked exceptions Goodies… or gotcha’s! javadoc
105. // more forms propagateIfInstanceOf(throwable,exceptionClass); propagateIfPossible(throwable); propagateIfPossible(throwable, exceptionClass); General practice: Convert checked exceptions to unchecked exceptions Checked exceptions... are a bad idea? Goodies… or gotcha’s! javadoc
106. // more forms propagateIfInstanceOf(throwable,exceptionClass); propagateIfPossible(throwable); propagateIfPossible(throwable, exceptionClass); General practice: Convert checked exceptions to unchecked exceptions Checked exceptions... are a bad idea? Don’t use propagate() to ignore IOExceptions and so on Goodies… or gotcha’s! javadoc
107. Think your fraking Exceptions Bottom line
108. Strings
109. Strings Splitter
110. We have String.split bro! Strings: Splitter
111. We have String.split bro! “,f,,o, o,”.split(“,”) returns: Strings: Splitter
112. We have String.split bro! “,f,,o, o,”.split(“,”) returns: a. [“”, “f”, “”, “o”, “ o”,””] Strings: Splitter
113. We have String.split bro! “,f,,o, o,”.split(“,”) returns: a. [“”, “f”, “”, “o”, “ o”,””] b. [null, “f”, null, “o” ,”o”, null] Strings: Splitter
114. We have String.split bro! “,f,,o, o,”.split(“,”) returns: a. [“”, “f”, “”, “o”, “ o”,””] b. [null, “f”, null, “o” ,”o”, null] c. [“f”, null, “o”, “o”] Strings: Splitter
115. We have String.split bro! “,f,,o, o,”.split(“,”) returns: a. [“”, “f”, “”, “o”, “ o”,””] b. [null, “f”, null, “o” ,”o”, null] c. [“f”, null, “o”, “o”] d. [“f”, ”o”, ”o”] Strings: Splitter
116. We have String.split bro! “,f,,o, o,”.split(“,”) returns: a. [“”, “f”, “”, “o”, “ o”,””] b. [null, “f”, null, “o” ,”o”, null] c. [“f”, null, “o”, “o”] d. [“f”, ”o”, ”o”] e. None of above Strings: Splitter
117. We have String.split bro! “,f,,o, o,”.split(“,”) returns: a. [“”, “f”, “”, “o”, “ o”,””] b. [null, “f”, null, “o” ,”o”, null] c. [“f”, null, “o”, “o”] d. [“f”, ”o”, ”o”] e. None of above Strings: Splitter
118. We have String.split bro! “,f,,o, o,”.split(“,”) returns: a. [“”, “f”, “”, “o”, “ o”,””] b. [null, “f”, null, “o” ,”o”, null] c. [“f”, null, “o”, “o”] d. [“f”, ”o”, ”o”] e. None of above Strings: Splitter
119. We have String.split bro! “,f,,o, o,”.split(“,”) returns: a. [“”, “f”, “”, “o”, “ o”,””] b. [null, “f”, null, “o” ,”o”, null] c. [“f”, null, “o”, “o”] d. [“f”, ”o”, ”o”] e. None of above Returns: [“”, “f”, “”, “o”, “ o”] Strings: Splitter
120. We have String.split bro! “,f,,o, o,”.split(“,”) returns: a. [“”, “f”, “”, “o”, “ o”,””] b. [null, “f”, null, “o” ,”o”, null] c. [“f”, null, “o”, “o”] d. [“f”, ”o”, ”o”] e. None of above Returns: [“”, “f”, “”, “o”, “ o”] Only trailing empty strings are skipped. Strings: Splitter
121. “,f,,o, o,”.split(“,”) we probably want [“f”,”o”,”o”] Strings: Splitter
122. “,f,,o, o,”.split(“,”) we probably want [“f”,”o”,”o”] Splitter.on(‘,’) .split(“,f,,o, o,”); Strings: Splitter
123. “,f,,o, o,”.split(“,”) we probably want [“f”,”o”,”o”] Splitter.on(‘,’) .split(“,f,,o, o,”); // returns [“”,”f”,””,”o”,” o”,””] // Doesn’t discard trailing separators! Strings: Splitter
124. “,f,,o, o,”.split(“,”) we probably want [“f”,”o”,”o”] Splitter.on(‘,’) .omitEmptyStrings() .split(“,f,,o, o,”); Strings: Splitter
125. “,f,,o, o,”.split(“,”) we probably want [“f”,”o”,”o”] Splitter.on(‘,’) .omitEmptyStrings() .split(“,f,,o, o,”); // returns [”f”,”o”,” o”] // Empty space is respected Strings: Splitter
126. “,f,,o, o,”.split(“,”) we probably want [“f”,”o”,”o”] Splitter.on(‘,’) .omitEmptyStrings() .trimResults() .split(“,f,,o, o,”); Strings: Splitter
127. “,f,,o, o,”.split(“,”) we probably want [“f”,”o”,”o”] Splitter.on(‘,’) .omitEmptyStrings() .trimResults() .split(“,f,,o, o,”); // returns [”f”,”o”,”o”] -- yay! Strings: Splitter
128. “,f,,o, o,”.split(“,”) we probably want [“f”,”o”,”o”] static final Splitter COMMA = Splitter.on(‘,’) .omitEmptyStrings() .trimResults() .split(“,f,,o, o,”); // Best practice: declare Splitters as static final Strings: Splitter javadoc
129. Strings Joiner
130. [“Jack, “Chloe”, “Tony”, null, “Nina”, “Logan”] Strings: Joiner
131. [“Jack, “Chloe”, “Tony”, null, “Nina”, “Logan”] Joiner.on(“, “) .join(twentyFour); Strings: Joiner
132. [“Jack, “Chloe”, “Tony”, null, “Nina”, “Logan”] Joiner.on(“, “) .join(twentyFour); // throws NullPointerException! Strings: Joiner
133. [“Jack, “Chloe”, “Tony”, null, “Nina”, “Logan”] Joiner.on(“, “) .join(twentyFour); // throws NullPointerException! // null-hostile operations everywhere, good thing ;) Strings: Joiner
134. [“Jack, “Chloe”, “Tony”, null, “Nina”, “Logan”] Joiner.on(“, “) .skipNulls(); .join(twentyFour); // returns “Jack, Chloe, Tony, Nina, Logan” Strings: Joiner
135. [“Jack, “Chloe”, “Tony”, null, “Nina”, “Logan”] Joiner.on(“, “) .useForNull(“Bill”); .join(twentyFour); // returns “Jack, Chloe, Tony, Bill, Nina, Logan” Strings: Joiner javadoc
136. Always think how to avoid null-idioty Bottom line
137. Strings CharMatcher
138. Your StringUtils replacement Strings: CharMatcher
139. Your StringUtils replacement CharMatcher.JAVA_ISO_CONTROL.removeFrom(string); // remove control chars Strings: CharMatcher
140. Your StringUtils replacement CharMatcher.JAVA_ISO_CONTROL.removeFrom(string); CharMatcher.DIGIT.retainFrom(“jordi9”); // returns 9 Strings: CharMatcher
141. Your StringUtils replacement CharMatcher.JAVA_ISO_CONTROL.removeFrom(string); CharMatcher.DIGIT.retainFrom(“jordi9”); CharMatcher.DIGIT.removeFrom(“jordi9”); // returns jordi Strings: CharMatcher
142. Your StringUtils replacement CharMatcher.JAVA_ISO_CONTROL.removeFrom(string); CharMatcher.DIGIT.retainFrom(“jordi9”); CharMatcher.DIGIT.removeFrom(“jordi9”); CharMatcher.DIGIT.or(CharMatcher.JAVA_UPPER_CASE).retainFrom(“Jordi9”); // returns J9 Strings: CharMatcher
143. // More matchers CharMatcher.ANY; CharMatcher.BREAKING_WHITESPACE; CharMatcher.WHITESPACE; CharMatcher.INVISIBLE; CharMatcher.DIGIT; // Unicode CharMatcher.JAVA_DIGIT; // Java’s definition CharMatcher.is(char); CharMatcher.isNot(char); Goodies! javadoc
144. // More matchers CharMatcher.ANY; CharMatcher.BREAKING_WHITESPACE; CharMatcher.WHITESPACE; CharMatcher.INVISIBLE; CharMatcher.DIGIT; // Unicode CharMatcher.JAVA_DIGIT; // Java’s definition CharMatcher.is(char); CharMatcher.isNot(char); // And operations .replaceFrom(charSequence, replacement); .collapseFrom(charSequence, replacement); .trimFrom(charSequence, replacement); Goodies! javadoc
145. Strings Escapers
146. HtmlEscapers.htmlEscaper().escape("Foo > bar"); // returns Foo &gt; bar Escapers
147. HtmlEscapers.htmlEscaper().escape("Foo > bar"); XmlEscapers.xmlAttributeEscaper().escape("foo \"bar\""); // returns foo &quot;bar&quot; Escapers
148. HtmlEscapers.htmlEscaper().escape("Foo > bar"); XmlEscapers.xmlAttributeEscaper().escape("foo \"bar\""); XmlEscapers.xmlContentEscaper().escape("foo \"bar\""); // returns foo “bar” Escapers
149. HtmlEscapers.htmlEscaper().escape("Foo > bar"); XmlEscapers.xmlAttributeEscaper().escape("foo \"bar\""); XmlEscapers.xmlContentEscaper().escape("foo \"bar\""); Escaper myEscaper = Escapers.builder() // custom Escaper .addEscape(‘\’’, “‘’”) .addEscape(‘&’, “\&”) .build(); Escapers javadoc
150. Collections
151. Collections: Functional Idiom
152. Collections: Functional Idiom
153. Collections: Functional Idiom
154. Function<String, Integer> lengthFunction = new Function<String, Integer>() { public Integer apply(String string) { return string.length(); } }; Predicate<String> allCaps = new Predicate<String>() { public boolean apply(String string) { return CharMatcher.JAVA_UPPER_CASE.matchesAllOf(string); } }; Multiset<Integer> lengths = HashMultiset.create( Iterables.transform(Iterables.filter(strings, allCaps), lengthFunction)); Collections: Functional Idiom
155. Function<String, Integer> lengthFunction = new Function<String, Integer>() { public Integer apply(String string) { return string.length(); } }; Predicate<String> allCaps = new Predicate<String>() { public boolean apply(String string) { return CharMatcher.JAVA_UPPER_CASE.matchesAllOf(string); } }; Multiset<Integer> lengths = HashMultiset.create( Iterables.transform(Iterables.filter(strings, allCaps), lengthFunction)); Collections: Functional Idiom
156. Multiset<Integer> lengths = HashMultiset.create(); for (String string : strings) { if (CharMatcher.JAVA_UPPER_CASE.matchesAllOf(string)) { lengths.add(string.length()); } } Collections: Functional Idiom
157. Multiset<Integer> lengths = HashMultiset.create(); for (String string : strings) { if (CharMatcher.JAVA_UPPER_CASE.matchesAllOf(string)) { lengths.add(string.length()); } } // Use Imperative, you’ve already survived! Collections: Functional Idiom
158. Multiset<Integer> lengths = HashMultiset.create(); for (String string : strings) { if (CharMatcher.JAVA_UPPER_CASE.matchesAllOf(string)) { lengths.add(string.length()); } } // Use Imperative, you’ve already survived! // Wait for Java 8! Collections: Functional Idiom explain
159. Immutable = Thread-safe Collections: Immutable types
160. Immutable = Thread-safe static final ImmutableSet<String> FOO_NAMES = ImmutableSet.of(“foo”, “bar”, “baz”); Collections: Immutable types
161. Immutable = Thread-safe static final ImmutableSet<String> FOO_NAMES = ImmutableSet.of(“foo”, “bar”, “baz”); // ImmutableList, ImmutableMap... Collections: Immutable types
162. Immutable = Thread-safe static final ImmutableSet<String> FOO_NAMES = ImmutableSet.of(“foo”, “bar”, “baz”); ImmutableList<String> defensiveCopy = ImmutableList.copyOf(someList); Collections: Immutable types
163. Immutable = Thread-safe static final ImmutableSet<String> FOO_NAMES = ImmutableSet.of(“foo”, “bar”, “baz”); ImmutableList<String> defensiveCopy = ImmutableList.copyOf(someList); // Prefer Immutable collections over JDK Collections.unmodifiableXX // for efficiency and consistency Collections: Immutable types explain
164. A bag Collections: Multiset<E>
165. A bag Just like a Set<E> with repeated values Collections: Multiset<E>
166. A bag Just like a Set<E> with repeated values You’ve done this with ArrayList<E> or Map<E, Integer> Collections: Multiset<E>
167. A bag Just like a Set<E> with repeated values You’ve done this with ArrayList<E> or Map<E, Integer> Multiset<Person> ppl = HashMultiset.create(); Collections: Multiset<E>
168. A bag Just like a Set<E> with repeated values You’ve done this with ArrayList<E> or Map<E, Integer> Multiset<Person> ppl = HashMultiset.create(); ppl.add(jack); ppl.add(charles); ppl.add(jack); Collections: Multiset<E>
169. A bag Just like a Set<E> with repeated values You’ve done this with ArrayList<E> or Map<E, Integer> Multiset<Person> ppl = HashMultiset.create(); ppl.add(jack); ppl.add(charles); ppl.add(jack); // prints [jack x 2, charles x 1] Collections: Multiset<E>
170. A bag Just like a Set<E> with repeated values You’ve done this with ArrayList<E> or Map<E, Integer> Multiset<Person> ppl = HashMultiset.create(); ppl.add(jack); ppl.add(charles); ppl.add(jack); ppl.count(jack); Collections: Multiset<E>
171. A bag Just like a Set<E> with repeated values You’ve done this with ArrayList<E> or Map<E, Integer> Multiset<Person> ppl = HashMultiset.create(); ppl.add(jack); ppl.add(charles); ppl.add(jack); ppl.count(jack); // returns 2 Collections: Multiset<E>
172. A bag Just like a Set<E> with repeated values You’ve done this with ArrayList<E> or Map<E, Integer> Multiset<Person> ppl = HashMultiset.create(); ppl.add(jack); ppl.add(charles); ppl.add(jack); ppl.count(jack); // Goodies: elementSet(), entrySet(), setCount(E, int)... Collections: Multiset<E> explain
173. A Map<K, V> with multiple values Collections: Multimap<K, V>
174. A Map<K, V> with multiple values You’ve done this with Map<K, List<V>> Collections: Multimap<K, V>
175. A Map<K, V> with multiple values You’ve done this with Map<K, List<V>> Multimap<Person, Ticket> ticketsByPerson = ArrayListMultimap.create(); Collections: Multimap<K, V>
176. A Map<K, V> with multiple values You’ve done this with Map<K, List<V>> Multimap<Person, Ticket> ticketsByPerson = ArrayListMultimap.create(); ticketsByPerson.put(jack, ctu); ticketsByPerson.put(jack, division); Collections: Multimap<K, V>
177. A Map<K, V> with multiple values You’ve done this with Map<K, List<V>> Multimap<Person, Ticket> ticketsByPerson = ArrayListMultimap.create(); ticketsByPerson.put(jack, ctu); ticketsByPerson.put(jack, division); ticketsByPerson.get(jack); // returns a view of the associated values, a List. // With SetMultimap returns a Set. Collections: Multimap<K, V>
178. A Map<K, V> with multiple values You’ve done this with Map<K, List<V>> Multimap<Person, Ticket> ticketsByPerson = ArrayListMultimap.create(); ticketsByPerson.put(jack, ctu); ticketsByPerson.put(jack, division); ticketsByPerson.get(jack); // asMap(), entries(), values()... Collections: Multimap<K, V> explain
179. // Bi-directional map, keys and values are unique BiMap<K1, K2> Goodies! javadoc
180. // Bi-directional map, keys and values are unique BiMap<K1, K2> // Two-tier map, or a map with two keys Table<R, C, V> Goodies! javadoc
181. // Bi-directional map, keys and values are unique BiMap<K1, K2> // Two-tier map, or a map with two keys Table<R, C, V> // < JDK 7, no diamond support List<String> list = Lists.newArrayList(); // Sets, Maps... Goodies! javadoc
182. // Bi-directional map, keys and values are unique BiMap<K1, K2> // Two-tier map, or a map with two keys Table<R, C, V> // < JDK 7, no diamond support List<String> list = Lists.newArrayList(); // Sets, Maps... // Ranges RangeSet<Integer> rangeSet = TreeRangeSet.create(); rangeSet.add(Range.closed(1, 10)); // {[1, 10]} Goodies! javadoc
183. Tons of good abstractions for you to use Bottom line
184. Hashing
185. Freaking PHP: md5($string) Hashing: JDK
186. Freaking PHP: md5($string) public static String md5Java(String message) { String digest = null; try { MessageDigest md = MessageDigest.getInstance("MD5"); byte[] hash = md.digest(message.getBytes("UTF-8")); String StringBuilder sb = new StringBuilder(2*hash.length); for(byte b : hash){ sb.append(String.format("%02x", b&0xff)); } digest = sb.toString(); } catch (UnsupportedEncodingException ex) { throw Throwables.propagate(ex); } catch (NoSuchAlgorithmException ex) { throw Throwables.propagate(ex); } return digest; } Hashing: JDK
187. Freaking PHP: md5($string) public static String md5Java(String message) { String digest = null; try { MessageDigest md = MessageDigest.getInstance("MD5"); byte[] hash = md.digest(message.getBytes("UTF-8")); String StringBuilder sb = new StringBuilder(2*hash.length); for(byte b : hash){ sb.append(String.format("%02x", b&0xff)); } digest = sb.toString(); } catch (UnsupportedEncodingException ex) { throw Throwables.propagate(ex); } catch (NoSuchAlgorithmException ex) { throw Throwables.propagate(ex); } return digest; } Hashing: JDK
188. HashFunction hf = Hashing.md5(); Hashing: Hasher
189. HashFunction hf = Hashing.md5(); HashCode hc = hf.newHasher() .putLong(id) .putString(name, Charsets.UTF_8) .putObject(person, personFunnel) .hash(); Hashing: Hasher
190. HashFunction hf = Hashing.md5(); HashCode hc = hf.newHasher() .putLong(id) .putString(name, Charsets.UTF_8) .putObject(person, personFunnel) // Defines how to hash .hash(); Hashing: Hasher
191. HashFunction hf = Hashing.md5(); HashCode hc = hf.newHasher() .putLong(id) .putString(name, Charsets.UTF_8) // HINT: remember this! .putObject(person, personFunnel) .hash(); Hashing: Hasher
192. HashFunction hf = Hashing.md5(); HashCode hc = hf.newHasher() .putLong(id) .putString(name, Charsets.UTF_8) .putObject(person, personFunnel) .hash(); hc.asBytes(); // byte[] hc.asInt(); // value in little-endian order hc.toString(); // hexadecimal in lower case Hashing: Hasher
193. // More hash functions! Hashing.md5(); Hashing.murmur3_32(); Hashing.murmur3_128(); Hashing.sha1(); Hashing.sha256(); Hashing.sha512(); Goodies! javadoc
194. // More hash functions! Hashing.md5(); Hashing.murmur3_32(); Hashing.murmur3_128(); Hashing.sha1(); Hashing.sha256(); Hashing.sha512(); // Bloom Filter public boolean mightContain(T); if true, T is probably there if false, T for sure is not there Goodies! javadoc
195. I/O
196. Binary encoding scheme, RFC 4648 I/O: BaseEncoding
197. Binary encoding scheme, RFC 4648 -- Serious stuff I/O: BaseEncoding
198. Binary encoding scheme, RFC 4648 BaseEncoding .base32() .encode("foo".getBytes(Charsets.US_ASCII)); I/O: BaseEncoding
199. Binary encoding scheme, RFC 4648 BaseEncoding .base32() .encode("foo".getBytes(Charsets.US_ASCII)); // returns MZXW6=== I/O: BaseEncoding
200. Binary encoding scheme, RFC 4648 BaseEncoding .base32() .encode("foo".getBytes(Charsets.US_ASCII)); // returns MZXW6=== byte[] decoded = BaseEncoding .base32() .decode("MZXW6==="); I/O: BaseEncoding
201. Binary encoding scheme, RFC 4648 BaseEncoding .base32() .encode("foo".getBytes(Charsets.US_ASCII)); // returns MZXW6=== byte[] decoded = BaseEncoding .base32() .decode("MZXW6==="); // returns the ASCII bytes of String “foo” I/O: BaseEncoding
202. // More schemas BaseEncoding.base16(); BaseEncoding.base32(); BaseEncoding.base64(); BaseEncoding.base64Url(); // Useful all the time Goodies! javadoc
203. KIA
204. KIA Caches EventBus
205. KIA Caches Networking EventBus Concurrency
206. KIA Caches Networking Math EventBus Concurrency More I/O
207. KIA Caches Networking Math Reflection EventBus Concurrency More I/O Collect
208. KIA Caches Networking Math Reflection Primitives EventBus Concurrency More I/O Collect Grumpy
209. Your friends Wiki
210. Your friends Wiki javadoc
211. Remember The “wheel”
212. Remember Read this code
213. Remember No Grumpy Cats were harmed in the making of this presentation
215. Thanks! jordi@donky.org @jordi9
216. Q & A jordi@donky.org @jordi9