Fix conflict

Abstract Keyword/AbstractExample.java

@@ -0,0 +1,32 @@
+// a abstract class
+abstract class H {
+    int x;
+
+    /* abstract */ int y; // variables cannot be abstract
+
+    /* abstract */ H () {x=1;} // constructor cannot be abstract
+
+    void triple  (int n) {x=x*3;}; // a normal method
+
+    static int triple2 (int n) {return n*3;}; // a static method in abstract class is ok.
+    abstract void triple3 (); // abstract method. Note: no definition.
+
+    // static abstract void triple3 (int n); // abstract static cannot be combined
+    int returnMe () {return x;}
+}
+
+// H1 extends (inherits) H. When a class extends a abstract class,
+// it is said to “implement” the abstract class.
+class H1 extends H {
+    void triple3 () {x=x*3+1;} // must be defined, else compiler makes a complaint.
+    //Also, all return type and parameter must agree with the parent class.
+}
+
+public class AbstractExample {
+    public static void main(String[] args) {
+        // H xx = new H(); // abstract class cannot be instantiated
+        H1 myO = new H1(); // abstract class cannot be instantiated
+        myO.triple3();
+        System.out.println(myO.returnMe());
+    }
+}

Abstract Keyword/README.md

@@ -0,0 +1,13 @@
+## The “abstract” Keyword
+
+1. The keyword abstract can be used on class declaration. For example abstract MyClassX (…);.
+1. The keyword abstract can be used on method declaration. For example abstract int f (…);.
+1. When a class is declared abstract, it cannot be instantiated.
+1. When a method is declared abstract, it cannot have definition.
+1. Only abstract classes can have abstract methods. Abstract class does not necessarily require its methods to be all abstract.
+
+## Purpose of Abstract Classes
+
+The purpose of abstract class is to serve purely as a parent of classes. (that is, solely for the purpose of extension (inheritance) by other classes.)
+
+The difference between abstract class and “normal” class is that, the abstract class's methods cannot have any definition.

CONTRIBUTING.md

@@ -9,7 +9,9 @@ First off, thanks for taking the time to contribute!
 *   The aim of the repository is mainly to help out newcomers to Java programming. Kindly keep that in
     mind and add necessary comments in your source code.
 
-*   Make the program user friendly. The user shouln't be left with doubts while running a program. 
+*   Make the program user friendly. The user shouln't be left with doubts while running a program.
+    For example : While requiring an user input , add a print statement along with it describing what
+    the user should input.
 
 *   Include your program within the appropriate package. For example all GUI's are included within 
     "guiprojects" package. 
@@ -34,8 +36,6 @@ There are various channels, on which you can ask questions:
 
 *   PM in Linkedin  : https://www.linkedin.com/in/yedhin1998
 
-*   Contact me via WhatsApp (intended for close friends)
-
 ## Code Style
 
 Refer to this [Code Convetion](http://www.oracle.com/technetwork/java/codeconvtoc-136057.html) while writing your source files.

Data Types And Operators/CommonDataTypes.java

@@ -0,0 +1,18 @@
+package operators;
+public class CommonDataTypes {
+    /**
+     * This program demonstrates common variable type usage and
+     * how to format output of variables.
+     */
+    public static void main(String[] args) {
+        String studentName = "Bette Itall";
+        int age = 22;       
+        double gpa = 3.75;
+        boolean isFemale = true;
+        System.out.printf("%s is %d years old. %s has a %4.3f gpa.\n",
+                studentName,
+                age,
+                (isFemale ? "She" : "He"),
+                gpa);
+    }
+}

Data Types And Operators/OnePlusTwoEqualsTwelve.java

@@ -0,0 +1,33 @@
+package operators;
+
+import java.util.Scanner;
+
+public class OnePlusTwoEqualsTwelve {
+
+    public static void main(String[] args) {
+        // 1 + 2 equals 12? Whaaaaaaaaaaaaat??!?!?!?
+        String x = "1";
+        String y = "2";
+        System.out.println(x + y);  // not what you expect;
+
+        String first = "Jimmy ";
+        String last = "Page";
+        System.out.println(first + last );
+
+        // so, how does one to convert string to int?
+        int i = Integer.parseInt(x);
+        int j = Integer.parseInt(y);
+
+        System.out.println(i + j);
+
+        // What about booleans? 
+        String areYouHappy = "true";
+        boolean ishappy = Boolean.parseBoolean(areYouHappy);
+        System.out.println(ishappy);
+
+        // Or String to double?
+        String gpa = "3.96";
+        Double realgpa = Double.parseDouble(gpa);
+        System.out.println(realgpa - 1.0 );
+    }
+}

Operators/README.md → Data Types And Operators/README.md

@@ -1,4 +1,7 @@
-# The Java programming language has around 30 operators as summarized below:
+## Primitive Data Types
+Check out this [link](https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html) to learn in detail about basic data types.
+
+## The Java programming language has around 30 operators as summarized below:
 ```
 Simple assignment
 =

Data Types And Operators/UnderstandingTypeCasting.java

@@ -0,0 +1,21 @@
+package operators;
+
+public class UnderstandingTypeCasting {
+
+    public static void main(String[] args) {
+        // This demo will help explain type casting.
+        int x = 20;
+        int y = 15;
+        int i = x / y;              // int / int == int
+        double d1 = x / y;          // int / int == int then cast to double
+        // implicit type cast
+        double d2 =  x / (y * 1.0); // int * double == double; int / double = double
+        // explicit type cast
+        double d3 = x / (double)y;  // int / double = double
+
+        System.out.println(i);
+        System.out.println(d1);
+        System.out.println(d2);
+        System.out.println(d3);
+    }
+}

EventHandling/sum_2nos.java

@@ -1,3 +1,4 @@
+package guiprojects;
 import java.awt.*;
 import java.awt.event.*;
 import java.applet.*;
@@ -15,7 +16,7 @@ public class sum_2nos extends Applet implements ActionListener
 
 	public void init()
 	{
-//		t1.setForeground(Color = Red);
+		//t1.setForeground(Color = Red);
 		add(l1);
 		add(t1);
 		add(l2);
@@ -36,4 +37,3 @@ public void actionPerformed(ActionEvent e)
 		}
 	}
 }
-

JDBCTemplate/JdbcBeg.java

@@ -0,0 +1,50 @@
+
+import java.sql.*;
+/********************
+  Contributed by leo
+  ->make sure that you have JDBC Driver install.
+  ->You should have a SQL server Running.
+************************/
+public class JdbcBeg implements Runnable{
+    //Threads are just used to make Server timings
+    public void run() {
+        System.out.print("Connecting to SQL DB waiting For Connection ");
+        for (int i = 0; i < 5; i++) {
+            try {
+                Thread.sleep(1000);
+                System.out.print(".");
+            } catch (InterruptedException e) {
+                System.out.println("Error while threading .");
+            }
+        }
+            System.out.println("\nYou are connected to SQL DB");
+
+    }
+    public static void main(String[] args) {
+        Thread thread=new Thread(new JdbcBeg());
+        thread.start();
+        try{
+            Thread.sleep(5000);
+            thread.join();
+        }catch (InterruptedException e){
+            System.out.println("Something wrong while threading.");
+        }
+
+        try {
+            //Connection is obtained using GET method. Replace the url,username,password with yours.
+            Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306", "root", "nopass1234");
+            Statement statement = connection.createStatement();
+            statement.executeUpdate("use employee");//Use your update statements instead of mine.
+            ResultSet resultSet = statement.executeQuery("select * from livesin");//Use your select queries here
+            //Result is stored as a ResultSet object
+            while (resultSet.next()) {
+                System.out.println();
+                System.out.println(resultSet.getString("pname") + "  " + resultSet.getString("street") + "  " + resultSet.getString("city") + " ");
+                //Replace the column label to columns used in the table
+            }
+
+        } catch (SQLException sqlException) {
+            System.out.println("Error occurred while processing");
+        }
+        }
+    }

JDBCTemplate/README.md

@@ -0,0 +1,21 @@
+# Requirements
+
+* Set up MySql
+	* [in Windows](https://www.roseindia.net/mysql/installing-mysql-on-windows10.shtml)
+	* [in most common Linux distros](https://dev.mysql.com/doc/refman/8.0/en/linux-installation.html)
+
+**in Arch Linux setting up both MySql and JDBC can be found [here](https://wiki.archlinux.org/index.php/JDBC_and_MySQL)**
+
+* Set up JDBC
+	* [in Windows](https://blogs.msdn.microsoft.com/brian_swan/2011/03/02/getting-started-with-the-sql-server-jdbc-driver/)
+	* [in Linux](https://stackoverflow.com/questions/5307048/where-do-i-install-a-jdbc-driver-on-ubuntu)
+
+## Creating your own Database in MySql (optional)
+
+After completing the installations , follow this [link](https://www.liquidweb.com/kb/create-a-mysql-database-on-linux-via-command-line/) and create a database of your own.
+Do this if you want to learn working with MySql. Else make use of the already created DB in the given example(s).
+
+## Usage
+
+Its important to note that , when , say you're in Arch Linux, then your default vendor is mariadb , thus in the program you would have to replace "mysql" with "mariadb".
+Rest of the execution as same as what had been done with other programs , compile and run `JdbcBeg.java`