cop 3330 notes 1/12. today's topics downloading java and eclipse hello world basic control...

COP 3330

Notes 1/12

Today's topics

• Downloading Java and Eclipse

• Hello World

• Basic control structures

• Basic I/O

• Strings

Downloading Java

Downloading Java

Downloading Java

Downloading Eclipse

Downloading Eclipse

Creating a Java Program With Eclipse

Creating a Java Program With Eclipse

Creating a Java Program With Eclipse

Creating a Java Program With Eclipse

Creating a Java Program With Eclipse

Running a Java Program With Eclipse

Running a Java Program With Eclipse

• Double-click Java Application

Running a Java Program With Eclipse

Running a Java Program Using Command Line

Running a Java Program Using Command Line

Running a Java Program Using Command Line

Running a Java Program Using Command Line

• Add the path of the bin directory of your JDK install to your path environment variable

• In my case:– C:\Program Files\Java\jdk1.5.0_04\bin

Running a Java Program Using Command Line

Running a Java Program Using Command Line

Running a Java Program Using Command Line

• If you get the error: – Exception in thread "main"

java.lang.NoClassDefFoundError: HelloWorldApp

• Make sure you’re in the same directory as your .java file and that you typed everything correctly

• If you still get the error, type at the command line: set CLASSPATH=

Java Virtual Machine

• Java is compiled to Java bytecode, not machine language

• Java bytecode is similar to machine code except that it is meant for the Java Virtual Machine (JVM)

• The JVM is an interpreter of Java bytecode (i.e. it runs Java programs)

Java Virtual Machine

• Machine language must be specific to a processor, so programs written in most languages must be recompiled to run on different processors

• The same compiled Java program can run on any computer that can run the correct version of the JVM