Added Information on OOPs, Packages, JVM, Threads (#1831)

Co-authored-by: “Mohamed <“dmdbilal8604@gmail.com”>
Co-authored-by: Kamran Ahmed <kamranahmed.se@gmail.com>

content/roadmaps/110-java/content/100-java-fundamentals/105-oop.md

@@ -1,4 +1,4 @@
-# OOPs
+# OOP
 
 Object-oriented programming is a core of Java Programming, which is used for designing a program using classes and objects. This can also be characterized as data controlling for accessing the code.
 

content/roadmaps/110-java/content/100-java-fundamentals/106-packages.md

@@ -3,5 +3,6 @@
 A package is a namespace that mainly contains classes and interfaces. For instance, the standard class `ArrayList` is in the package `java.util`. For this class, `java.util.ArrayList` is called its fully qualified name because this syntax has no ambiguity. Classes in different packages can have the same name. For example, you have the two classes `java.util.Date` and `java.sql.Date`, which are different. If no package is declared in a class, its package is the default package.
 
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+<BadgeLink colorScheme='blue' badgeText='Official Site' href='https://docs.oracle.com/javase/8/docs/api/java/lang/Package.html'>Packages in Java</BadgeLink>
 <BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.javatpoint.com/package'>Java Package</BadgeLink>
 <BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.geeksforgeeks.org/packages-in-java/'>Packages In Java</BadgeLink>

content/roadmaps/110-java/content/101-java-advanced-topics/106-how-jvm-works.md

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 The Java Virtual Machine is a program whose purpose is to execute other programs. JVMs are available for many hardware and software platforms (i.e. JVM is platform dependent). JVM is the one that actually calls the main method present in a java code. JVM is a part of JRE(Java Runtime Environment)                                                                                                     
 
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+<BadgeLink colorScheme='blue' badgeText='Official Site' href='https://docs.oracle.com/javase/8/docs/api/java/lang/Package.html'>Packages in Java</BadgeLink>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.javatpoint.com/jvm-java-virtual-machine'>What is JVM?</BadgeLink>
 <BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.infoworld.com/article/3272244/what-is-the-jvm-introducing-the-java-virtual-machine.html'>Introducing the Java Virtual Machine</BadgeLink>
 <BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.geeksforgeeks.org/jvm-works-jvm-architecture/'>JVM Architecture</BadgeLink>
 <BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.javatpoint.com/jvm-java-virtual-machine'>JVM (Java Virtual Machine) Architecture</BadgeLink>
+<BadgeLink badgeText='Watch' href='https://youtu.be/G1ubVOl9IBw'>How JVM works?</BadgeLink>

content/roadmaps/110-java/content/101-java-advanced-topics/108-basics-of-threads.md

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 A thread in Java is the direction or path that is taken while a program is being executed. Generally, all the programs have at least one thread, known as the main thread, that is provided by the JVM or Java Virtual Machine at the starting of the program’s execution
 
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+<BadgeLink colorScheme='blue' badgeText='Official Site' href='https://docs.oracle.com/javase/7/docs/api/java/lang/Thread.html'>Threads in Java</BadgeLink>
 <BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.simplilearn.com/tutorials/java-tutorial/thread-in-java'>An Introduction to Thread in Java</BadgeLink>
 <BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.geeksforgeeks.org/java-threads/'>Java Threads</BadgeLink>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.javatpoint.com/how-to-create-a-thread-in-java'>How to Create a Thread in Java?</BadgeLink>
 <BadgeLink badgeText='Watch' href='https://www.youtube.com/watch?v=TCd8QIS-2KI'>Java Threads Tutorial</BadgeLink>
+<BadgeLink badgeText='Watch' href='https://youtu.be/TCd8QIS-2KI'>Threads in Java</BadgeLink>