Java Puzzle Ball - Oracle

Java Puzzle BallNick RistucciaLesson 0What is Java?Copyright 2017, Oracle and/or its affiliates. All rights reserved.

Lesson 0 is Optional Lesson 1 is where the real fun starts!– But you'll need Java 8 or higher installed to run Java Puzzle Ball. Lesson 0 gives an overview of Java and what you'll be installing.– But you won't need to know these technical details for this course.– You can skip Lesson 0 and go right to Lab 0. Lab 0 gives installation instructions so that you can – Play Java Puzzle Ball.– Edit Java code.Copyright 2017, Oracle and/or its affiliates. All rights reserved. 3

Purpose of a Computer ProgramA computer program is a set of instructionsthat run on a computer or other digitaldevice. At the machine level, the program consists ofbinary instructions (1s and 0s).– Machine code Most programs are written in high-level code(readable).– Must be translated to machine codeCopyright 2017, Oracle and/or its affiliates. All rights reserved. 4

Translating High-Level Code to Machine CodeA compiler converts your codeinto a CPU-specific code calledmachine code. These arebinary files, which areplatform-specific.Copyright 2017, Oracle and/or its affiliates. All rights reserved. 5

Linked to Platform-Specific LibrariesA binary file is linked withlibraries to create aplatform-dependentexecutable.For example, a Windowsbinary only makes sense toWindows machines.Copyright 2017, Oracle and/or its affiliates. All rights reserved. 6

Platform-Dependent ProgramsPlatform-dependentexecutables work on onlyone platform. For example,.exe's for Windows.Programs written in mostlanguages usually requirenumerous modifications torun on more than one typeof platform. Programmersdon't like this extra work.Copyright 2017, Oracle and/or its affiliates. All rights reserved. 7

Java Is Platform-IndependentA Java program can run on several different CPUs and operating systemcombinations, usually with few or no modifications.Java programs are compiled with a Java compiler. The resulting format of acompiled Java program is platform-independent Java bytecode instead ofCPU-specific machine code.Copyright 2017, Oracle and/or its affiliates. All rights reserved. 8

Java Programs Run in a JVMA Java Virtual Machine (JVM)interprets the bytecode,allowing the program to runon any machine with a JavaRuntime Environment (JRE)installed.Java VirtualMachine(JVM)Programmers like writingtheir applications once, andhaving it run everywhere.Copyright 2017, Oracle and/or its affiliates. All rights reserved. 9

Java Runtime Environment (JRE) Includes:– The Java Virtual Machine (JVM)– Java class libraries Purpose:JRE– Read bytecode (.class)– Run the same bytecode anywhere with a JVMCopyright 2017, Oracle and/or its affiliates. All rights reserved. 10

Java Development Kit (JDK) Includes:– JRE– Java Compiler– Additional toolsJDK Purpose:– Compile bytecode (.java .class)Copyright 2017, Oracle and/or its affiliates. All rights reserved. 11

Integrated Development Environment (IDE) Purpose:– Provide a sophisticated text editor– Offer assistance debugging code– Manage projects– Write source code (.java)NetBeansIDE Examples:– NetBeans– Eclipse– Greenfoot and BlueJCopyright 2017, Oracle and/or its affiliates. All rights reserved. 12

Your CodeThe code you type inNetBeans will look likethis:You'll look like this whenyour code finally works:It often won't work andwill need debugging first.Copyright 2017, Oracle and/or its affiliates. All rights reserved.

Compiling and Running a Java ProgramWriteNetBeans.javaCompile.classJDKCopyright 2017, Oracle and/or its affiliates. All rights reserved. RunJRE14

Summary A computer program is written in a high-level language, but must becompiled into machine code. Most programming languages compile a separate executable for eachplatform. Java is platform-independent.An IDE like NetBeans is used to write source code (.java).The JDK compiles bytecode (.java .class).Bytecode runs in a JVM, which is part of the JRE.Copyright 2017, Oracle and/or its affiliates. All rights reserved. 15

A Java program can run on several different CPUs and operating system combinations, usually with few or no modifications. Java programs are compiled with a Java compiler. The resulting format of a compiled Java program is platform-independent Java bytecode instead of CPU-specific machine code. Java Is Platform-Independent 8