An Introduction to Java – Part 1 Dylan Boltz

What is Java?  An object-oriented programming language  Developed and released by Sun in 1995  Designed to bridge the gap between digital consumer devices and computers  Syntax very similar to that of C++

Basic Program Structure public class ClassName { public static void main(String[] args) { program statements } user defined methods }

Things to Remember About the Structure  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.

Operators  Arithmetic Operators: +, -, *, /, %  Relational Operators: ==, !=,, =  Logical Operators: &&, ||, !

Data Types  Integers – int, short, long, byte  Floating-Point Types – float, double  Character Type – char  Boolean Type – boolean (values: true, false)

Strings  Standard class in Java  ‘+’ used for string concatenation  Example:  String greeting = “hello”;  Member Functions:  int compareTo(String other)  boolean equals(Object other)  int length()

Variables  Variables need to be declared  Variables must be initialized before use  Examples:  int year = 2010;  System.out.println(year);  String greeting = “Hello”;  String name = “Bob”;  System.out.println(greeting + “ “ + name);

Conditional Statements  If/else statements similar to C++  Curly braces not required for enclosing a single instruction Example: If(…){ … }else{ … } Example: If(…) … else …

Loops  While Loops  Similar to C++  Example  while(…){  …  }  For Loops  Also similar to C++  Example  for(initialization; condition; update){  …  }

Arrays  Also similar to C++  Arrays are a standard class in Java  Selected Member Functions  static void sort(type [ ] a)  static int binarySearch(type [ ] a, type v)  static boolean equals(type [ ] a, Object other) Example: int[ ] numbers = new int[ 10 ]; for(int i = 0; i < numbers.length; i++) numbers[ i ] = i;

Resources  anguage_basics.pdf anguage_basics.pdf   java/data/basic_types/21integers.html java/data/basic_types/21integers.html  java/data/basic_types/22floatingpoint.html java/data/basic_types/22floatingpoint.html