JAVA v1

Image source: Willi Glenz - Java

public class Tools {
    public String getInput(String prompt) {
        String tmp = null;
        System.out.print(prompt + " ");
        try {
            BufferedReader is = new BufferedReader(new InputStreamReader(System.in));
            tmp = is.readLine();
            if (tmp.length() == 0) {
                return null;
            }
        } catch (Exception e) {
            System.out.println("IOException: " + e);
        }
        return tmp;
    }
}

White Paper     : oracle.com/technetwork/java/langenv-140151.html

Getting Started : docs.oracle.com/javase/tutorial/getStarted/index.html
Language Basics : docs.oracle.com/javase/tutorial/java/nutsandbolts/index.html
Object-Oriented Programming Concepts : docs.oracle.com/javase/tutorial/java/concepts/index.html
Classes and Objects : docs.oracle.com/javase/tutorial/java/javaOO/index.html
Interfaces and Inheritance : docs.oracle.com/javase/tutorial/java/IandI/index.html
Numbers and Strings : docs.oracle.com/javase/tutorial/java/data/index.html
Packages        : docs.oracle.com/javase/tutorial/java/package/index.html
Exceptions      : docs.oracle.com/javase/tutorial/essential/exceptions/index.html
Basic I/O       : docs.oracle.com/javase/tutorial/essential/io/index.html
Concurrency     : docs.oracle.com/javase/tutorial/essential/concurrency/index.html
Generics        : docs.oracle.com/javase/tutorial/java/generics/index.html
Annotations     : docs.oracle.com/javase/tutorial/java/annotations/index.html
Swing           : tutorialspoint.com/swing/index.htm

chortle.ccsu.edu/java5/index.html
oreilly.com/openbook/javawt/book/index.html
tutorialspoint.com/java/index.htm

docs.oracle.com/javase/7/docs/api/index.html?overview-summary.html
docs.oracle.com/javase/8/docs/api/index.html?overview-summary.html
docs.oracle.com/javase/9/docs/api/index.html?overview-summary.html
docs.oracle.com/javase/10/docs/api/index.html?overview-summary.html
 
$ java -version
$ javac -version
# apt-get install default-jdk default-jdk-doc
# apt-get install openjdk-8-jdk openjdk-8-doc
# update-java-alternatives -l
# update-java-alternatives -s java-1.11.0-openjdk-amd64
# update-alternatives --display java
# update-alternatives --config java
$ screen vim ~/java/Main.java
$ ( cd ~/java/; vim Main.java )

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

// BASICS 01
public class SolarSystem {
    public static void main(String[] args) {
        String[] objects = { "Sun", "Mercury", "Venus", "Earth", "Mars", "Jupiter", "Saturn", "Uranus", "Neptune", "Centaurs", "Comets", "Kuiper belt", "Scattered disk", "Heliosphere", "Detached objects", "Oort cloud", "Boundaris" };
        for (int i = 0; i < objects.length; i++) {
            System.out.println(objects[i]);
        }
    }
}

// BASICS 02
public class SolarSystem {
    public static void main(String[] args) {
        String[] objects = { "Sun", "Mercury", "Venus", "Earth", "Mars", "Jupiter", "Saturn", "Uranus", "Neptune", "Centaurs", "Comets", "Kuiper belt", "Scattered disk", "Heliosphere", "Detached objects", "Oort cloud", "Boundaris" };
        for (String i : objects) {
            System.out.println(i);
        }
    }
}

//BASICS 03
public class Tools {
    public String getInput(String prompt) {
        String tmp = null;
        System.out.print(prompt + " ");
        try {
            BufferedReader is = new BufferedReader(new InputStreamReader(System.in));
            tmp = is.readLine();
            if (tmp.length() == 0) {
                return null;
            }
        } catch (Exception e) {
            System.out.println("IOException: " + e);
        }
        return tmp;
    }
}