LEARNING JAVA v19-03-20 Update

LEARNING JAVA
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Screenshot by Willi Glenz

BASIC GUI-SNIPPET v0.002

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() {
        //
    }

}

BASIC CLI-SNIPPET

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);
   }
}

MODIFIER

                Class Package Subclass World
private            ok       -        -     -
default            ok      ok        -     -
protected          ok      ok       ok     -
public             ok      ok       ok    ok

OPERATORS

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

PRIMITIVE DATA TYPES

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

WRAPPER CLASSES

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)

SWING

TutorialsPoint - Learning Swing
Oracle Trail - Swing
O'Reilly - AWT Reference

ORACLE-JAVA-TUTORIALS

JAVA-BASICS

Learning Java - tutorialspoint • javatpoint
Bradley Kjell - Introduction to Computer Science using Java
IdeOne - Online Compiler and IDE

TERMINAL

# 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 )