Java
/
Collections
- 1 Basics 9
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Classes S
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Objects S
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Arrays S
-
Variables S
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Loops S
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Numbers S
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Strings S
-
Exceptions S
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Regexp S
- 2 OOP 9
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Inheritance
-
Polymorphism
-
Static S
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Abstract
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Interfaces
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Constructors S
-
Packages
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Nested Classes
-
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
-
Maps
-
Generics
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Properties
-
Streams
-
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
-
Timer
-
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
-
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
-
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
-
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
-
On Action
-
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
Config
Java properties file is normaly used to store project configuration data or settings.
/**
* Properties file to store project configuration data.
* Use getProperty() to get values.
*/
package com.minte9.collections.properties;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
public class Config {
public static void main(String[] args) throws IOException {
InputStream input = new FileInputStream(
"java-pages/src/main/java/com/minte9/" +
"collections/properties/" +
"config.properties"
);
Properties props = new Properties();
props.load(input);
String user = props.getProperty("db.user");
int port = Integer.parseInt(
props.getProperty("db.port")
);
System.out.println("user: " + user); // my_user
System.out.println("port: " + port); // 9000
}
}
/*
*/
List
Use list() or forEach() for quick parsing.
/**
* Use Enumeration to loop through a properties file.
* User forEach to access every property.
*/
package com.minte9.collections.properties;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
public class List {
public static void main(String[] args) throws IOException{
InputStream input = new FileInputStream(
"java-pages/src/main/java/com/minte9/" +
"collections/properties/" +
"config.properties"
);
Properties props = new Properties();
props.load(input);
props.list(System.out);
/*
-- listing properties --
db.user=my_user
db.pass=my_password
db.port=9000
db.url=localhost
*/
props.forEach((k, v) -> {
System.out.println(k + " : " + v);
});
/*
db.user : my_user
db.pass : my_password
db.port : 9000
db.url : localhost
*/
}
}
System
You can access many useful System properties.
/**
* Use list() to print all System properties.
*/
package com.minte9.collections.properties;
public class SystemProperties {
public static void main(String[] args) {
System.getProperties().list(System.out);
/*
...
os.name=Linux
java.vm.specification.version=11
sun.java.launcher=SUN_STANDARD
user.country=US
sun.boot.library.path=/usr/lib/jvm/java-11-openjdk-amd64/lib
....
*/
System.out.println(
System.getProperty("os.name") // Linux
);
}
}
➥ Questions