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effective java
The document discusses best practices in Java programming, particularly around optimizing for loops, managing multiple parameters in classes, and using design patterns like the builder and JavaBeans. It highlights performance comparisons, such as the efficiency of manual vs enhanced for-loops, and suggests methods to avoid unnecessary object creation, including using static initializers and factory methods. Overall, it emphasizes improving code readability and scalability while ensuring safety and immutability.
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effective java
- 1. Globalcode – Open4education Trilha– Android Bruno Fernandes Campos Desenvolvedor Mobile EFFECTIVE JAVA
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- 5. Globalcode – Open4education Agenda •What the difference in performance between for loops? • How to deal with several parameters classes? • How to make static classes safe? • How to avoid the unecessary objects creation? • Inside classes • Inside for loops • When concatenating strings
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- 7. Globalcode – Open4education ForLoops In Arrays Manual for-loop x Enhanced for-loop
- 8. Globalcode – Open4education ForLoops In Arrays Manual for-loop x Enhanced for-loop SAME PERFORMANCE WHEN READING ENTRANCES
- 9. Globalcode – Open4education Forloops in Collections For each X Iterator
- 10. Globalcode – Open4education Forloops in Collections For each X Iterator SAME PERFORMANCE
- 11. Globalcode – Open4education Forloops in ArrayLists Manual for-loop X For each
- 12. Globalcode – Open4education Forloops in ArrayLists X For eachManual for-loop
- 13. Globalcode – Open4education Forloops in ArrayLists X 1061 ms 1183 ms For each 100000 strings logged in the console performance test Manual for-loop
- 14. Globalcode – Open4education ManyConstructors Parameters What should I do?
- 15. Globalcode – Open4education NutritionFacts Class
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- 17. Globalcode – Open4education UsingTelescoping Constructor Pattern ● Force some unwanted values ● It does not scale well! ● Parameters reversion
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- 19. Globalcode – Open4education JavabeansPattern ● Easy to read ● Precludes the possibility of making a class imutable ● Imutability -> "All of the information contained in each instance is provided when it is created and is fixed for the lifetime of the object"
- 20. Globalcode – Open4education Thebuilder pattern!
- 21. Globalcode – Open4education UsingBuilder Pattern ● Easy to read and Write ● Safe -> Imutable
- 22. Globalcode – Open4education Howto turn static classes safe
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- 26. Globalcode – Open4education AndroidAPIUtilsavoiding instantiability
- 27. Globalcode – Open4education AvoidCreating Unecessary Objects
- 28. Globalcode – Open4education PrefeerStatic Factory Methods Constructors will always create a new instance!
- 29. Globalcode – Open4education INSIDECLASSES Avoid Creating Unecessary Objects
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- 31. Globalcode – Open4education UseStatic initializers
- 32. Globalcode – Open4education Whyuse static initialisers? ● Calendar, Date and Timezone instances created only once ● Executing 10 milion times : ○ 1st version took 32000ms ○ 2nd version took 130 ms 250 times faster!
- 33. Globalcode – Open4education INSIDEFOR LOOPS Avoid Creating Unecessary Objects
- 34. Globalcode – Open4education Badpractice at for loops
- 35. Globalcode – Open4education Goodallocation example
- 36. Globalcode – Open4education WHENCONCATENATING STRINGS Avoid Creating Unecessary Objects
- 37. Globalcode – Open4education BadPractice
- 38. Globalcode – Open4education BadPractice ● Strings are immutable ● Complexity square n
- 39. Globalcode – Open4education GoodPractice ● Linear complexity ● 85 times faster than the first one for 8.000 strings.
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