1. An Introduction to Java – Part I, language basics
By: Mihir Shah

2. Overview Basic Structrue Source code, Compilation, Execution
Data Types, Operators, Strings
Variables
If statements, Loops
Arrays

3. Basic Structure
The basic structure of Java programs: public class ClassName { public static void main(String[] args) {
program statements }
User defined methods
Explanations:
Public classes are accessible from any class.
Classes, which are not declared public are accessible only within their package
Public methods may be called from any class.
Static methods do not operate on objects.
The keyword void indicates that the method does not return a value.
The array args of the main method stores command line arguments.

4. Source code, Compilation, Execution
Source code should be same name as the public class
File must be saved with the extension .java
Ex. Public class TestFile
File name: TestFile.java
To run the command type java then the file name
Ex. Java TestFile

5. Data Types, Operators, Strings
Integers: int, short, long, byte
Floating-Point Types: float, double
The Character Type: char
The Boolean Type: boolean (values: true, false)
Operators
Arithmetic Operators: +, -, *, /, %
Relational Operators: ==, !=, <, >, <=, >=
Logical Operators: &&, ||, !
Strings
Enclosed in “”
Concatenate with +
Int Length();

6. Variables Need to be declared Ex: Int n = 5; System.out.println(n);
Output: 5
String s = “Hello”;
String t = “World”;
System.out.println(s+“ ”+t);
Output: Hello World

7. If statements, Loops If statements While loop For Loops
if(…) { … } else { … }
While loop
while(….) { … }
For Loops
for(initialization; condition; update) { … }

8. Arrays Standard class in java
Defined by specifying the array type followed by []
Create objects with operator new
Array count is from 0 to length-1
arrayName.length
Examples
int n = 5;
int[] numbers = new int[n];
for(int i=0; i<numbers.length; i++) numbers[i]=n-i; for(int i=0; i<numbers.length; i++) system.out.println(numbers[i]);