Java Introduction DengRung Liu 87715 Outline 4 History

Java Introduction 劉登榮 Deng-Rung Liu 87/7/15

Outline 4 History 4 Why Java? 4 Java Concept 4 Java in Real World 4 Language Overview 4 Java Performance!? 4 Conclusion

History (1/2) 4 Consumer electronics technology 4 Hardware & Software Difference 4 Programming language bottleneck 4 New Language Solution

History (2/2) 4 Proposed by Sun Microsystem 4 For Consumer Electronics 4 Not Only For Consumer Electronics 4 New Language ? (Updating)

Why Java ? (1/3) 4 Language trend (High-Level) 4 Object-Oriented world 4 Security requirement (Machine & To Yourself) 4 Internet hot! (Interactive Document)

Why Java ? (2/3) 4 Applications in the OS(Seldom Using Applications) 4 Real World? ! Different Platform? ! (How to cross different platform) 4 Write-Once-Run-Anywhere ! (Quickly Development) 4 Integrated with new technology

Why Java ? (3/3) 4 Distributed computing trend (RMI) 4 Backward compatibility (Only Related to Java Virtual Machine) 4 Fit wireless communication (low bandwidth required) 4 Some news!

Java Concept (1/6) 4 Java Virtual Machine (JVM) Java Source Code JVM (Intel) Intel/ Windows PC Java Compiler JVM (Sun) SPARC/ Solaris Workstation Byte Code Other Architectures Supporting JVM

Java Concept (2/6) 4 Java Runtime Environment (JRE) Class loader & bytecode verifier Interpreter Garbage Collector awt io net. . . Java class libraries JIT . . . Threads and Synchronization JVM

Java Concept (3/6) 4 100% Object-Oriented Programming Language 4 C-Like grammar 4 Different Packages & Interfaces

Java Concept (4/6) 4 Relation between JVM & Application 4 Interpreter & JIT (Just-In-Time Compiler) 4 JDK (Java Development Kit) & JVM 4 Java Version

Java Concept (5/6) 4 Development Environment JDK Visual J++ Symantec Café 4 No pointer in Java (Object Reference) 4 No memory management mechanism (Garbage Collector)

Java Concept (6/6) 4 Java Native Interface (JNI) JN I In Po terfa c int er e Array of pointers to JNI functions Pointer Per-thread JNI data structure C Language Function Pointer Native method . . .

Java in Real World 4 IC Card Machine 4 Consumer Electronics 4 Very small Hand Computer (Java Chip) 4 Will be HOT in Consumer Electronics

Language Overview 4 Sample Code

Java Defect? ! (1/2) 4 Hardware interface 4 Interpreter language performance 4 Java bug!? 4 Lack OS support

Java Defect? ! (2/2) 4 OS attention 4 Not popular language for programmer 4 Sun Microsystem

Conclusion 4 A New Programming Language 4 Cross-Platform Implementation 4 Java Chip 4 Java OS 4 Other OS Support 4 Project Experience Sharing