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
Constants
p157 Before Enum, group constants were used.
/**
* Before Enum, a commont pattern was to use group contants
*/
package com.minte9.effective.enums;
public class Constants {
public static void main(String[] args) {
System.out.println(
Utils.Color.ANSI_RED + "This text is red!" +
Utils.Color.ANSI_RESET
);
}
}
class Utils {
public static class Color {
public static final String ANSI_RESET = "\u001B[0m";
public static final String ANSI_BLACK = "\u001B[30m";
public static final String ANSI_RED = "\u001B[31m";
public static final String ANSI_GREEN = "\u001B[32m";
public static final String ANSI_YELLOW = "\u001B[33m";
public static final String ANSI_BLUE = "\u001B[34m";
public static final String ANSI_PURPLE = "\u001B[35m";
public static final String ANSI_CYAN = "\u001B[36m";
public static final String ANSI_WHITE = "\u001B[37m";
}
}
Classes
p158 Enum types are classes that export one instance for each enumaration constant.
/**
* Enum types
*
* Are classes that exports one instance for each enumaration constant.
* An Enum can start as a simple collection of enum and evolve over time.
*/
package com.minte9.effective.enums;
public class Classes {
public static void main(String[] args) {
System.out.println(Planet.MERCURY);
// MERCURY
System.out.println(Color.PURPLE + "Purple 1!" + Color.RESET);
// Purple 1!
System.out.println(Color2.PURPLE + "Purple 2!" + Color.RESET);
// Purple 2!
System.out.println(Color3.PURPLE + "Purple 3!" + Color.RESET);
// Purple 3!
}
}
enum Planet {
MERCURY, VENUS, EARTH, MARS, JUPITER, SATURN, URANUS, NEPTUNE
}
enum Color {
RESET, BLACK, RED, GREEN, YELLOW, BLUE, PURPLE, CYAN, WHITE;
public String toString() {
switch(this) {
case RESET: return "\u001B[0m";
case BLACK: return "\u001B[30m";
case RED: return "\u001B[31m";
case GREEN: return "\u001B[32m";
case YELLOW: return "\u001B[33m";
case BLUE: return "\u001B[34m";
case PURPLE: return "\u001B[35m";
case CYAN: return "\u001B[36m";
case WHITE: return "\u001B[37m";
default: return null;
}
}
}
enum Color2 {
RESET("\u001B[0m"), BLACK("\u001B[30m"), RED("\u001B[31m"),
GREEN("\u001B[32m"), YELLOW("\u001B[33m"), BLUE("\u001B[34m"),
PURPLE("\u001B[35m"), CYAN("\u001B[36m"), WHITE("\u001B[37m");
private final String value;
private Color2(String c) {
value = c;
}
public String toString() {
return value;
}
}
enum Color3 {
RESET { public String toString() { return "\u001B[0m"; } },
BLACK { public String toString() { return "\u001B[30m"; } },
RED { public String toString() { return "\u001B[31m"; } },
GREEN { public String toString() { return "\u001B[32m"; } },
YELLOW { public String toString() { return "\u001B[33m"; } },
BLUE { public String toString() { return "\u001B[34m"; } },
PURPLE { public String toString() { return "\u001B[35m"; } },
CYAN { public String toString() { return "\u001B[36m"; } },
WHITE { public String toString() { return "\u001B[37m"; } };
}
Type safety
The primary advantage of using enum vs constants is type safety.
/**
* Enum type safety ...
*
* The primary advantage of using enum vs constants is type safety.
* With enum only the applicable values can be used.
*/
package com.minte9.effective.enums;
public class TypeSafety {
public static void main(String[] args) {
Tools.print("This text is purple!", C.PURPLE);
// This text is purple!
Tools.print("This text is purple underline!", "\033[4;35m"); // allowed
// This text is purple underline!
Tools.output("This text is purple!", ColorEnum.PURPLE);
// This text is purple!
// Tools.output("This text is purple!", "\033[4;35m"); // Look Here
// not applicable for the arguments
}
}
class Tools {
public static void print(String message, String color) {
System.out.println(color + message + Color.RESET);
}
public static void output(String message, ColorEnum color) { // Look Here
System.out.println(color + message + Color.RESET);
}
}
class C {
public static final String RESET = "\u001B[0m";
public static final String BLACK = "\u001B[30m";
public static final String RED = "\u001B[31m";
public static final String GREEN = "\u001B[32m";
public static final String YELLOW = "\u001B[33m";
public static final String BLUE = "\u001B[34m";
public static final String PURPLE = "\u001B[35m";
public static final String CYAN = "\u001B[36m";
public static final String WHITE = "\u001B[37m";
}
enum ColorEnum {
RESET { public String toString() { return "\u001B[0m"; } },
BLACK { public String toString() { return "\u001B[30m"; } },
RED { public String toString() { return "\u001B[31m"; } },
GREEN { public String toString() { return "\u001B[32m"; } },
YELLOW { public String toString() { return "\u001B[33m"; } },
BLUE { public String toString() { return "\u001B[34m"; } },
PURPLE { public String toString() { return "\u001B[35m"; } },
CYAN { public String toString() { return "\u001B[36m"; } },
WHITE { public String toString() { return "\u001B[37m"; } };
}
➥ Questions
Last update: 512 days ago