Java
/
Effective
- 1 Basics 9
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Classes S
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Objects S
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Arrays S
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Variables S
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Loops S
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Numbers S
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Strings S
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Exceptions S
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Regexp S
- 2 OOP 9
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Inheritance
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Polymorphism
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Static S
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Abstract
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Interfaces
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Constructors S
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Packages
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Nested Classes
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Final
- 3 Compiler 2
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Sublime Text S
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Apache Ant
- 4 Collections 8
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Lists
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Comparable S
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Sets
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Maps
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Generics
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Properties
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Streams
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Json
- 5 Threads 4
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Create Thread S
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Sleep
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Lock
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Scheduler
- 6 Design Patterns 4
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Singleton
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Observer
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Strategy
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Mediator
- 7 Swing 12
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Frame
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Panel
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Listener
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Combo Box
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Label
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Image
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Menu
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Table
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Layout
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Drawing
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Timer
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Designer
- 8 I/O 7
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Streams IO
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Socket
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Watching Files
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Mail
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Logger
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Clipboard
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Encrypt S
- 9 Effective 7
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Constructors S
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Dependency Injection
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Composition
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Interfaces Default
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Import Static S
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Enums
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Lambdas
- 10 Junit 5
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About Junit S
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Test Case
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Suite Test
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Annotations
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Exceptions
- 11 Lambdas 7
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Expressions S
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Functional Interfaces
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Streams
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Common Operations
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Default Methods
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Static Methods S
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Single Responsibility
- 12 JavaFX 6
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Openjfx
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Scene Builder
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First App
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Jar Archive
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On Action
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Change Listener
- 13 Maven 4
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Demo
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Spring Boot
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Junit
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Guava
- 14 Spring Boot 13
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Quick start S
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Rest service S
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Consuming rest S
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Templates S
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Security auth S
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Command line S
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Scheduled task S
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Ajax S
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Jdbc mysql S
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Encrypt password S
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Https S
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Jwt S
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Post request S
R
Q
Default methods
p102 Prior to Java 8, adding new methods to interfaces breaks existing implemenations.
/**
* Starting with Java 8 ...
* interfaces can have default method construct
*/
package com.minte9.effective.interfaces_default;
public class DefaultMethods {
public static void main(String[] args) {
new Login().subscribe();
// Default subscribe method
new Subscribe().subscribe();
// Default subscribe method - overwritten
}
}
interface Commandable {
public abstract void getCommand();
public default void subscribe() { // Look Here
System.out.println("Default subscribe method");
}
}
class Subscribe implements Commandable {
@Override public void getCommand() {
}
@Override public void subscribe() {
System.out.println("Default subscribe method - overwritten");
}
}
/**
* Old class - don't need to imnplement subscribe()
*/
class Login implements Commandable {
@Override public void getCommand() {
}
//subscribe() overwitten - not needed!
}
Contract
p104 An interface is a contract, don't use interfaces for inheritance!
/**
* Default methods for existing interfaces ...
* should be avoided unless the need is critical.
*
* A default method added to an interface break main scope ...
* which is to unsure a valid contract betwween classes.
*/
package com.minte9.effective.interfaces_default;
public class Contract {
public static void main(String[] args) {
new Subscribe();
}
}
interface A {
public default void getCommand() {
}
public default void subscribe() {
}
}
class B implements A {
// there is no need to override subscribe() so ...
// the contract is no longer valid!
}
➥ Questions