<center>**LEARNING JAVA**<br><a href="https://www.oracle.com/java/">homepage</a><a href="https://www.oracle.com/technetwork/java/langenv-140151.html"> whitepaper</a><a href="https://docs.oracle.com/en/java/javase/11/"> documentation</a><a href="https://www.oracle.com/technetwork/java/javase/downloads/index.html"> download</a><a href="https://docs.oracle.com/en/java/javase/11/docs/api/index.html"> api</a></center>


<center>![Screenshot](https://files.steempeak.com/file/steempeak/wglenz/elYArpDm-image.png)Screenshot by Willi Glenz</center>


<center><b>BASIC GUI-SNIPPET v0.002</b></center>
```
package de.wglenz.java;

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class Main {

	JFrame frame;
	JLabel label;
	JButton button1;
	JButton button2;
	JButton button3;

	public Main() {
		super();

		label = new JLabel("Empty");
		button1 = new JButton("Button 1");
		button1.addActionListener(new Listener1());

		button2 = new JButton("Button 2");
		button2.addActionListener(new Listener2());

		button3 = new JButton("Button 3");
		button3.addActionListener(new Listener3());

		frame = new JFrame("Phoenix");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.getContentPane().add(BorderLayout.WEST, button1);
		frame.getContentPane().add(BorderLayout.SOUTH, button2);
		frame.getContentPane().add(BorderLayout.EAST, button3);
		frame.getContentPane().add(BorderLayout.CENTER, label);
		frame.setSize(600, 400);
		frame.setVisible(true);
	}

	public static void main(String... args) {
		Main phoenix = new Main();
		phoenix.run();
	}

	class Listener1 implements ActionListener {
		public void actionPerformed(ActionEvent e) {
			label.setText("Button 1: OK");
		}
	}

	class Listener2 implements ActionListener {
		public void actionPerformed(ActionEvent e) {
			label.setText("Button 2: OK");
		}
	}

	class Listener3 implements ActionListener {
		public void actionPerformed(ActionEvent e) {
			label.setText("Button 3: OK");
		}
	}

	public void run() {
		//
	}

}

```


<center><b>BASIC CLI-SNIPPET</b></center>
```
public class Main {
   private String msg;

   public Main() {
      super();
      this.msg = "Hello World!";
   }

   public static void main(String[] args) {
      Main phoenix = new Main();
      phoenix.run();
   }

   public void run() {
      System.out.println(msg);
   }
}
```

<center><b>MODIFIER</b></center>
```
				Class Package Subclass World
private			   ok		-		 -	   -
default			   ok	   ok		 -	   -
protected		   ok	   ok	    ok     -
public			   ok	   ok		ok	  ok
```


<center><b>OPERATORS</b></center>
```
Arithmetic		+ - * / & ++ --
Relational		== != > < >= <=
Bitwise			& | ^ ~ << >> >>>
Logical			&& || !
Assignment		= += -= *= /= %= <<= >>=  &= ^= |=
Miscellaneous	?: instanceof
```



<center><b>PRIMITIVE DATA TYPES</b></center>
|Type|Size|Range|Default|Class & Field|
|-|-|-|-|-|
|byte|8 bit|-2^7 to 2^7 -1|0||
|short|16 bit|-2^15 to 2^15 -1|0||
|int|32-bit|-2^31 to 2^31 -1|0|Integer.MIN_VALUE to Integer.MAX_VALUE|
|long|64 bit|-2^63 to 2^63-1|0L||
|float|32 bit|-3.4E38 to 3.4E38|0f||
|double|64 bit|-1.7E308 to 1.7E308|0d||
|char|16 bit|'\u0000' to '\uffff' (0 to 65,565)|'\u0000'||
|boolean|1 bit||false||

<center><b>WRAPPER CLASSES</b></center>
```
public Byte(byte|String value|s)
public Short(short|String value|s)
public Integer(int|String value|s)
public Long(long|String value|s)
public Float(float|double|String value|value|s)
public Double(double|String value|s)
public Character(char value)
public Boolean(boolean|String value|s)
```

<center><b>SWING</b></center>
- TutorialsPoint - <a href="https://www.tutorialspoint.com/swing/index.htm">Learning Swing</a>
- Oracle Trail - <a href="https://docs.oracle.com/javase/tutorial/uiswing/">Swing</a>
- O'Reilly - <a href="https://www.oreilly.com/openbook/javawt/book/index.html">AWT Reference</a>



<center><b>ORACLE-JAVA-TUTORIALS</b></center>
- <a href="https://docs.oracle.com/javase/tutorial/getStarted/"> Getting Started</a>
- <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/index.html"> Language Basics</a>
- <a href="https://docs.oracle.com/javase/tutorial/java/concepts/index.html"> Object-Oriented Programming Concepts</a>
- <a href="https://docs.oracle.com/javase/tutorial/java/javaOO/index.html">Classes and Objects</a>
- <a href="https://docs.oracle.com/javase/tutorial/java/IandI/index.html">Interfaces and Inheritance</a>
- <a href="https://docs.oracle.com/javase/tutorial/java/data/index.html">Numbers and Strings</a>
- <a href="https://docs.oracle.com/javase/tutorial/java/package/index.html">Packages</a>
- <a href="https://docs.oracle.com/javase/tutorial/essential/exceptions/index.html">Exceptions</a>
- <a href="https://docs.oracle.com/javase/tutorial/essential/io/index.html">Basic I/O</a>
- <a href="https://docs.oracle.com/javase/tutorial/essential/concurrency/index.html">Concurrency</a>
- <a href="https://docs.oracle.com/javase/tutorial/java/generics/index.html">Generics</a>
- <a href="https://docs.oracle.com/javase/tutorial/java/annotations/index.html">Annotations</a>



<center><b>JAVA-BASICS</b></center>
- Learning Java - <a href="https://www.tutorialspoint.com/java/index.htm">tutorialspoint </a>• <a href="https://www.javatpoint.com/java-tutorial">javatpoint </a>
- Bradley Kjell - <a href="https://chortle.ccsu.edu/java5/index.html">Introduction to Computer Science using Java</a>
- IdeOne - <a href="https://ideone.com/"> Online Compiler and IDE</a>



<center><b>TERMINAL</b></center>
```
# apt-get install default-jdk default-jdk-doc openjdk-11-jdk openjdk-11-doc
$ java -version; javac -version
# update-java-alternatives -l
# update-java-alternatives -s java-1.11.0-openjdk-amd64
# update-alternatives --display java
# update-alternatives --config java
$ mkdir -p /tmp/java/{tools,test,phoenix};cd /tmp/java; ls -lisa
$ vim Main.java ^z fg
$ ( cd /tmp/java/; vim Main.java )
```