Java Basic Training: Hello World
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This document provides an overview of basic Java training. It covers: - Setting up a development environment including choosing an editor, installing the JDK, and configuring a terminal emulator. - Java language fundamentals such as variables, operators, control flow statements, and packages. - Classes and objects including access modifiers, constructors, static vs instance members, and initializing fields. - Other concepts like naming conventions, coding style, and annotations. - Exercises are provided to practice each topic. Homework includes completing an online Java course and writing an address book program.
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Java Basic Training: Hello World
- 1. JAVA BASIC TRAINING I. The Language Essentials
- 2. HELLO WORLD HelloWorld.java with default package HelloWorld.java with named package > javac HelloWorld.java > java HelloWorld
- 3. PREPARATION
- 4. DEVELOPMENT SETUP Editor Choose anyone you prefer But do not rush to IDE Make sure you’ve killed “tab” JDK JDK not JRE 6 not 7 Terminal Emulator Unix, Linux, Mac, but sorry M$
- 5. NAMING CONVENTION Package com.ericsson.ma.javatraining Class/Interface HelloWorld Method helloWorld(); Variable String helloWorld = “Hello World”; Constant HELLO_WORLD http://java.about.com/od/javasyntax/a/nameconventions.htm
- 6. CODING STYLE Similar with C++ Space instead of tab Always make block with {} Already defined for EMA development (Eclipse): Get it here: /proj/EMA/env/formatter.xml Or install the all-in-one shot
- 7. VARIABLES
- 8. VARIABLES Instance Variables Class Variables Local Variables Parameters
- 9. VARIABLES Primitive Types byte (0) short (0) int (0) long (0L) float (0.0f) double (0.0d) boolean (false) char (‘u0000’) Object Array is an object must be initialized primitive/object Value or References
- 10. EXERCISES Try some illegal field names Test default values
- 11. OPERATORS
- 12. OPERATORS Mostly the Same as C++ equals and == instanceof
- 15. CONTROL FLOW STATEMENTS Enhanced for statement Never use labeled break/continue Avoid continue and break Always use {} to clarify blocks
- 16. EXERCISES Enhanced for statement Write a small program to give number of days of a specified month Read from standard input Input like “1”, “2”, “3”, “quit”; if “quit”, terminate
- 17. PACKAGE
- 18. PACKAGE Naming Conventions java and javax are reserved by Java language itself domain name + product name Importing Package import com.ericsson.ma.javatraining.HelloWorld; import static com.ericsson.ma.javatraining.HelloWorld.say; import com.ericsson.ma.javatraining.*; Managing Source and Class Files Not required to rely on file system to manage source and class files As a universal convention, please rely on file system
- 19. EXERCISES Refactor three classes into three different packages com.ericsson.ma.javatraining.Server => c.e.m.j.s com.ericsson.ma.javatraining.Utilities => c.e.m.j.u com.ericsson.ma.javatraining.Client => c.e.m.j.c
- 20. CLASS AND OBJECT
- 21. CLASS AND OBJECT Class Constructor/”Destructor” Class Hierarchy Modifier Method and Field Object Instance of Class Garbage Collector
- 22. CLASS AND OBJECT Modifier Class Package Subclass World public Y Y Y Y Access Control protected Y Y Y N no modifier Y Y N N private Y N N N
- 23. CLASS AND OBJECT Class Members aka, static methods/fields Thread-safety Instance Members
- 24. CLASS AND OBJECT Initializing Fields Instance Fields Class Fields Static Block
- 25. EXERCISES Write a few classes to represent Resource, Tester, Designer Common fields like id, gender, name, unit Test can test while designer can design, so the behaviors of working are different The following code creates one array and one string object. How many references to those objects exist after the code executes? Is either object eligible for garbage collection? ... String[] students = new String[10]; String studentName = "Peter Parker"; students[0] = studentName; studentName = null; ...
- 26. ANNOTATION
- 27. ANNOTATION Information for the Compiler Used by compiler to detect errors and suppress warnings Compiler-time and Deployment-time Processing Software tools can process annotation to generate XML, files, and so on Runtime Processing Available to be examined at runtime
- 28. EXERCISES Try @Override in previous test/designer exercise Try @SuppressWarnings
- 29. HOMEWORK Finish all sections of http://t.cn/Ste59J Strongly recommend http://t.cn/SteofW Write an address book program Store name, address, phone number Possbile to search by phone number, either complete or partial
Editor's Notes
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- - everything from stratch\n- default package, HelloWorld.java\n > main\n > pure OO\n- named package\n\n
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- try to explain these in HelloWorld.java\n\nfield concept\n
- - show literals\n- show array usage\n- ArrayCopyDemo without print out for exercise\n
- - name like 1test\n- field default values, local variable default values\n
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- write examples to show equals and ==\n\nString a = “hello”;\nString b = “hello”;\n\na.equals(b);\na == b\n\nString a = new String(“hello”);\nString b = new String(“hello”);\n\na.equals(b);\na == b\n
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- for (int a : array) {\n}\n
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- describe when to use static import and not overuse it\n
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- there is no multi-inherits\n\nshape, rectangle, triangle to show class hierarchy\n
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- mention thread safety here\n
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- show -cp option when compiling\n
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