Download to read offline
![A Java file
public class Foo {
public static void main(String[] args) {
System.out.println("Hello World!");
}
}
6](https://image.slidesharecdn.com/javagoeswildlesson1-141007110313-conversion-gate02/85/Java-goes-wild-lesson-1-6-320.jpg)
![Practice #2
Given the following code:
public class Foo {
public static void main(String[] args) {
System.out.println("Hello World!");
}
}
28](https://image.slidesharecdn.com/javagoeswildlesson1-141007110313-conversion-gate02/85/Java-goes-wild-lesson-1-28-320.jpg)
Uploaded byThierry Wasylczenko
Java goes wild, lesson 1
The document is an introductory lesson on Java programming by Thierry Wasylczenko, covering basic concepts such as setting up the JDK/JRE, compiling Java programs, and running them. It explains the structure of Java files, the role of the Java Virtual Machine, and how to establish a developer's environment. Practical exercises are provided to reinforce the learning of compiling and executing Java code.
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Similar to Java goes wild, lesson 1
Java goes wild, lesson 1
- 1. Java goes wild Lesson 1: Introduction to Java Thierry Wasylczenko
- 2. After this course... You will: • Know what is the JDK/JRE • Be able to set up your development environment • Know how to compile and run a Java program 2
- 3. Agenda • Bascis • How does all of this work? • Developer’s environment 3
- 4. Basics Success isneither magical nor mysterious. Success is the natural consequence of consistently applying the basic fundamentals. Jim Rohn “ 4
- 5. Basics • Sourcecode is inside files with .java extension • The source code is compiled into .class files • The class files are executed by a strange thing (covered later) 5
- 6. A Java file public class Foo { public static void main(String[] args) { System.out.println("Hello World!"); } } 6
- 7. How do Iget class files? • By compiling all Java files $ cd /location/of/java/files $ javac Foo.java $ ls Foo.class Foo.java $ 7
- 8. How do Irun it? • With the java command $ java Foo Hello World! $ • Yes you DON’T put the .class extension when you run a class ! 8
- 9. Java Archive •aka JAR • A collection of compiled Java classes • Package of a Java program • Can be runnable java -jar Foo.jar 9
- 10.
- 11. That’s awesome dude.But how does all of this work? You “ 11
- 12. 12 How doesall of this work? It is not the beauty of a building you should look at; it's the construction of the foundation that will stand the test of time. David Allan Coe “
- 13. The source code • Plain text file • File extension: .java • Rules for naming each file (covered later) 13
- 14. The bytecode 14 • Result of compilation • Something in between the source code and the machine’s language • Interpreted by the Java Virtual Machine
- 15. The Java VirtualMachine • aka the JVM • Kind of a black box • Interprets the Java bytecode • Is available on major platforms • "Compile once, run everywhere" 15
- 16. A little schema Source code Source code Byte code JVM Byte code JVM turns on turns on java java javac javac 16
- 17. Well man, you’retalking about JVM, javac, bytecode and cool stuff. But how do I set them up? You “ 17
- 18. 18 Developer's environment When people think about computer science, they imagine people with pocket protectors and thick glasses who code all night. Marissa Mayer “
- 19. Java Development Kit • aka JDK • Provides tools • javac: java compiler • javadoc: generates the documentation • ... • Includes a Java Runtime Environment 19
- 20. Java Runtime Environment • aka JRE • Provides tools: • java: for running Java applications • ... 20
- 21. JAVA_HOME • Anenvironment variable • Points to the JDK installation • Required by some tools such as: • IDEs • build tools (maven, gradle, ...) • ... • Used to update the PATH variable 21
- 22. JAVA_HOME: example #Unix export JAVA_HOME="/path/to/jdk" export PATH=$JAVA_HOME/bin:$PATH REM Windows set JAVA_HOME="C:pathtojdk" set PATH=%JAVA_HOME%bin;%PATH% 22
- 23. Avoid spaces inthe path of your JAVA_HOME. JAVA_HOME 23
- 24. JAVA_HOME: test thesetup To test the setup you can execute the following command: 24 $ java -version java version "1.8.0_11" Java(TM) SE Runtime Environment (build 1.8.0_11-b12) Java HotSpot(TM) 64-Bit Server VM (build 25.11-b03, mixed mode)
- 25. What does JREstand for? • Java Runtime Embeded • Java Routine Exclusive • Java Runtime Environment Start Stop 25
- 26. What is thecorrect command to execute a Java program? • java Foo.java • java Foo • java Foo.class Start Stop 26
- 27. 1. Set theJAVA_HOME in your environment 2. Verify your setup Practice #1 27
- 28. Practice #2 Giventhe following code: public class Foo { public static void main(String[] args) { System.out.println("Hello World!"); } } 28
- 29. 1. Copy itin your favorite editor 2. Save the file as Foo.java 3. Compile it 4. Run it Practice #2 29
- 30.
- 31.
- 32. Appendix • JavaCode conventions • Not maintained since 1997, may not be accurate 32