added content to 100-java-fundamentals (#2491)

content/roadmaps/110-java/content/100-java-fundamentals/100-basic-syntax.md

@@ -2,6 +2,9 @@
 
 Understanding the basics is the key to a solid foundation. In this section, learn the basic terminologies, naming conventions, reserved words, conditions, functions, data structures, OOP, packages, etc.
 
+* To print output use --> System.out.println();
+* To take input from user --> Scanner or BufferedReader class can be used
+
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 <BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.geeksforgeeks.org/java-basic-syntax/'>Basic Java Syntax</BadgeLink>
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content/roadmaps/110-java/content/100-java-fundamentals/101-data-types-variables.md

@@ -2,6 +2,10 @@
 
 Variable in Java is a data container that stores the data values during Java program execution. Every variable is assigned a data type, which designates the type and quantity of values it can hold. Variable is a memory location name of the data. The Java variables have mainly three types: Local, Instance and Static.
 
+Data Types are divided into two group -
+* Primitive - byte,short,int,long,float,double,boolean and char
+* Non-Primitive - String, Arrays and Classes
+
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content/roadmaps/110-java/content/100-java-fundamentals/102-conditionals.md

@@ -6,6 +6,7 @@ Java has the following conditional statements:
 * Use `else` to specify a block of code to be executed if the same condition is false
 * Use `else if` to specify a new condition to test; if the first condition is false
 * Use `switch` to specify many alternative blocks of code to be executed
+* Use `?,:` operator to specify one line condition
 
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content/roadmaps/110-java/content/100-java-fundamentals/103-functions.md

@@ -2,6 +2,10 @@
 
 A method/function is a way to perform some task. Similarly, in programming like Java, a function method is a block of code written to perform a specific task repeatedly. It provides reusability of code. We write the function once and use it many times. It works on the 'DRY' principle i.e., "Do not repeat yourself".
 
+Steps -
+1. Define function - datatype function_name(parameters){body}
+2. Call function - function_name(values)
+
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content/roadmaps/110-java/content/100-java-fundamentals/104-datastructures.md

@@ -2,6 +2,11 @@
 
 As the name indicates itself, a **Data Structure** is a way of organizing the data in the **memory** so that it can be used efficiently. Some common data structures are array, linked list, stack, hashtable, queue, tree, heap, and graph.
 
+* Array allocates continuous memory for homogeneous data
+* Linked List stores data in nodes with references
+* Stack follows Last In First Out principle
+* Queue follows First In First Out principle
+
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content/roadmaps/110-java/content/100-java-fundamentals/106-files-and-apis.md

@@ -2,6 +2,9 @@
 
 Learn how to work with files i.e., reading, writing and deleting, files and folders, etc. Also, learn how to make API calls, parse the incoming response, and so on.
 
+* FileWriter - this class is useful to create a file by writing characters into it
+* FileReader - this class is useful to read data in form of characters from file
+
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content/roadmaps/110-java/content/100-java-fundamentals/106-packages.md

@@ -2,6 +2,8 @@
 
 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.
 
+To create package use this command -> javac -d directory javafilename
+
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content/roadmaps/110-java/content/100-java-fundamentals/107-loops.md

@@ -1,6 +1,10 @@
 # Loops
 
-In Java and other programming languages, loops are used to iterate a part of the program several times. There are three types of loops in Java, `for`, `while`, and `do...while`.
+In Java and other programming languages, loops are used to iterate a part of the program several times. There are four types of loops in Java, `for`, `forEach`, `while`, and `do...while`.
+
+* Synatx of `for` loop is `for(initialization;condition;increment/decrement){}`
+* Syntax of `forEach` loop is `for(data_type variable:array_name){}`
+
 
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content/roadmaps/110-java/content/100-java-fundamentals/108-exception-handling.md

@@ -2,6 +2,11 @@
 
 Exception Handling in Java is one of the effective means to handle the runtime errors so that the regular flow of the application can be preserved. Java Exception Handling is a mechanism to handle runtime errors such as ClassNotFoundException, IOException, SQLException, RemoteException, etc.
 
+There are three types of exceptions -
+1. Checked Exception - exceptions checked at compile time. Example - IOException
+2. Unchecked Exception - exceptions checked at run time. Example - NullPointerException
+3. Error - It is irrecoverable. Example - OutOfMemoryError
+
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