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Download Jdk 1.8 for Mac

How to Install JDK 17 (on Windows, macOS & Ubuntu) and Go Started with Java Programming

The Coffee Development Kit (JDK), officially named "Java Platform Standard Edition" or "Java SE", is needed for writing and running Java programs.

JDK Variants

In that location are few variants of JDK:

OpenJDK: Currently, the "OpenJDK" developed by Oracle and the Java customs (@ https://openjdk.java.net/) provides a costless and open-source JDK official reference implementation.
OracleJDK: This article is based on the "OracleJDK" (@ https://www.oracle.com/coffee/) (due to legacy), which is free for personal and development use but no longer free for commercial utilise.

JDK Versions

Reference: "Java Version History" @ https://en.wikipedia.org/wiki/Java_version_history.

JDK Alpha and Beta (1995): Sun Microsystem announced Coffee in September 23, 1995.
JDK 1.0 (January 1996): Originally called Oak (named after the oak tree exterior James Gosling's role). Renamed to Java 1 in JDK ane.0.2.
JDK i.1 (February 1997): Introduced AWT event model, inner class, JavaBean, JDBC, and RMI.
J2SE 1.2 (JDK 1.2) (December 1998): Re-branded as "Java 2" and renamed JDK to J2SE (Java 2 Standard Edition). Also released J2EE (Java 2 Enterprise Edition) and J2ME (Java two Micro Edition). Included JFC (Java Foundation Classes - Swing, Accessibility API, Java 2D, Pluggable Expect & Feel, and Drag & Drop). Likewise introduced Drove Framework and JIT compiler.
J2SE 1.three (JDK 1.3) (May 2000): Introduced Hotspot JVM.
J2SE 1.iv (JDK 1.4) (February 2002): Introduced assert statement, non-blocking IO (nio), logging API, image IO, Java webstart, regular expression (regex) back up.
J2SE 5.0 (JDK 5) (September 2004): Officially called 5.0 instead of one.5 (by dropping the 1.). Introduced generics, autoboxing/unboxing, annotation, enum, varargs, for-each loop, static import. Run into "JDK 5 New Features".
Java SE 6 (JDK six) (December 2006): Renamed J2SE to Java SE (Java Platform Standard Edition). No new language features. See "JDK 6 New Features".
Java SE 7 (JDK vii) (July 2011): First version later on Oracle purchased Dominicus Microsystem - aslo called OracleJDK. Introduced Strings in switch statement, Binary integer literals, allowing underscores in numeric literals, improved type inference for generic example creation (or diamond operator <>), Catching multiple exception types and rethrowing exceptions with improved type checking. Run into "JDK 7 New Features".
Coffee SE eight LTS (JDK eight) (March 2014): Included support for Lambda expressions, default and static methods in interfaces, improved collection, and JavaScript runtime. Also integrated JavaFX graphics subsystem. See "JDK 8 New Features".
Coffee SE 9 (JDK ix) (September 21, 2017): Introduced modularization of the JDK (module) under projection Jigsaw, the Coffee Shell (jshell), and more. See "JDK nine New Features".
Java SE 10 (18.3) (JDK 10) (March 2018): Introduced var for type inference local variable (similar to JavaScript). Introduced time-based release versioning with ii releases each year, in March and September, denoted as YY.M. Removed native-header generation tool javah. See "JDK 10 New Features".
Coffee SE eleven LTS (18.9) (JDK eleven) (September 2018): Extended var to lambda expression. Standardize HTTP customer in java.cyberspace.http. Support TLS 1.three. Clean up the JDK and the installation package (removed JavaFX, JavaEE, CORBA modules, deprecated Nashorn JavaScript engine). OracleJDK is no longer gratis for commercial use, but OpenJDK is yet gratuitous. See "JDK 11 New Features".
Java SE 12 (19.3) (JDK 12) (March 2019): Switch Expression (preview). Run into "JDK 12 New Features".
Java SE xiii (19.nine) (JDK thirteen) (September 2019): Switch Expression (preview), Multi-line Text Cake (preview). Encounter "JDK 13 New Features".
Coffee SE 14 (20.3) (JDK fourteen) (March 2020): Records (preview)
Java SE 15 LTS (twenty.nine) (JDK 15) (September 2020):
Java SE sixteen (JDK 16) (March 2021):
Coffee SE 17 LTS (JDK 17) (September 2021):
Java SE xviii (JDK xviii) (March 2022):

"JDK" or "JRE"?

JRE (Java Runtime), which include a Java Virtual Machine and core libraries, is needed for running Java programs. JDK (Coffee Development Kit), which includes JRE plus the development tools (such as compiler and debugger), is need for writing as well as running Java programs. In other words, JRE is a subset of JDK. Since y'all are supposed to write Coffee Programs instead of merely running Java programs, you should install JDK, which includes JRE.

How To Install JDK on Windows

Footstep 0: United nations-Install Older Version(s) of JDK/JRE

I recommend that y'all install only the latest JDK. Although you can install multiple versions of JDK/JRE meantime, it is messy.

If you have previously installed older version(s) of JDK/JRE, un-install ALL of them. Goto "Control Panel" ⇒ (optional) "Programs" ⇒ "Programs and Features" ⇒ Un-install ALL programs begin with "Java", such equally "Java SE Development Kit ...", "Java SE Runtime ...", "Java Ten Update ...", and etc.

Step 1: Download JDK

Goto JDK (or Java SE) download site @ https://www.oracle.com/java/technologies/javase-downloads.html.
Under "Java SE Development Kit 17.0.{ten} downloads".
Select "Windows" ⇒ Download the "x64 Installer" (eastward.g., "jdk-17_windows-x64_bin.exe" - nearly 152MB).

Step 2: Install JDK

Run the downloaded installer. Accept the defaults and follow the screen instructions to complete the installation. By default, JDK is installed in directory "C:\Program Files\Java\jdk-17.0.{x} ", where {x} denotes the running "update number" starting from 1.

Launch "File Explorer". Navigate to "C:\Program Files\Coffee" to inspect this directories. Take note of your JDK Installed Directory jdk-17.0.{x} , in particular, the update number {x} .

I shall refer to the JDK Installed Directory equally <JAVA_HOME> , futurity, in this article (corresponding to surround variable %JAVA_HOME% in Windows or $JAVA_HOME in Unix/macOS).

Step 3: (SKIP for JDK 17, 16, sixteen - kept for completeness) Include JDK's "bin" Directory in the PATH

Windows' Control Prompt (CMD) searches the current directory and the directories listed in the PATH surround variable for executable programs.

JDK'southward programs (such equally Coffee compiler "javac.exe" and Java runtime "java.exe") reside in the sub-directory "bin" of the JDK installed directory. JDK'south "bin" needs to be added into the PATH.

Prior to JDK 15, you need to explicitly add JDK's "bin" into the PATH. Starting from JDK fifteen, the installation process adds the directory "C:\Program Files\Common Files\Oracle\Java\javapath" to the PATH. The "javapath" directory is a link to "javapath_target_xxxxxx", which contains a copy of the post-obit JDK programs:

java.exe: Java Runtime
javac.exe: Java Compiler
javaw.exe: Coffee Runtime for Windows Console-less
jshell.exe: Coffee Control-line Shell (since JDK 10) - a Read-Evaluate-Print Loop (REPL) which evaluates declarations, statements, and expressions as they are entered and immediately shows the results.

Link is used so that you tin can continue multiple copies (versions) of JDK.

To edit the PATH environment variable in Windows 10:

Launch "Control Console" ⇒ (Optional) "System and Security" ⇒ "Organization" ⇒ Click "Advanced system settings" on the left pane.
Switch to "Avant-garde" tab ⇒ Click "Environment Variables" button.
Under "Organisation Variables" (the bottom pane), scroll down to select variable "Path" ⇒ Click "Edit...".
For Newer Windows 10:
You shall come across a TABLE listing all the existing PATH entries (if not, goto side by side step). Click "New" ⇒ Click "Browse" and navigate to your JDK'due south "bin" directory, i.e., "c:\Plan Files\Java\jdk-15.0.{10}\bin ", where {ten} is your installation update number ⇒ Select "Motion Upward" to move this entry all the style to the TOP.
For Older Windows 10 (Fourth dimension to change your computer!):
(Caution: Read this paragraph iii times before doing this step! Don't push "Use" or "OK" until you are 101% certain. There is no Undo!!!)
(To exist SAFE, copy the content of the "Variable value" to Notepad before changing information technology!!!)
In "Variable value" field, APPEND "c:\Program Files\Java\jdk-15.0.{x}\bin" (where {x} is your installation update number) IN FRONT of all the existing directories, followed by a semi-colon (;) to split up the JDK's bin directory from the rest of the existing directories. Practise NOT DELETE any existing entries; otherwise, some existing applications may non run.
```
Variable name  :                              PATH                            Variable value :                              c:\Program Files\Java\jdk-15.0.{x}\bin;                            [do not delete exiting entries...]            
```

Yous need to re-started CMD for the new environment settings to take consequence.

Stride four: Verify the JDK Installation

Launch a CMD via i of the following ways:

Click "Search" button ⇒ Blazon "cmd" ⇒ Cull "Control Prompt", or
Correct-click "Get-go" button ⇒ run... ⇒ enter "cmd", or
Click "Start" button ⇒ Windows System ⇒ Command Prompt

Issue the post-obit commands to verify your JDK installation:

(Skip for JDK 17, sixteen, 15) Issue "path" command to list the contents of the PATH environment variable. Check to make sure that your JDK's "bin" is listed in the PATH.
```
              path              PATH=c:\Program Files\Java\jdk-{xx.y.z}\bin;other entries...            
```

Upshot the following commands to verify that JDK/JRE are properly installed and brandish their version:

                javac -version              javac                17.0.one                                          java -version              java version "17.0.i" 2021-x-xix LTS Java(TM) SE Runtime Environs (build 17.0.1+12-LTS-39) Java HotSpot(TM) 64-Chip Server VM (build 17.0.1+12-LTS-39, mixed fashion, sharing)

Step 5: Write a How-do-you-do-Globe Coffee Program

Create a directory to keep your works, e.m., "d:\myProject" or "c:\myProject". Do Not save your works in "Desktop" or "Documents" every bit they are hard to locate. The directory name shall not contain blank or special characters. Use meaningful but short name as it is easier to type.
Launch a programming text editor (such equally TextPad, NotePad++, Sublime Text, Atom). Begin with a new file and enter the following source code. Save the file as "How-do-you-do.java", nether your work directory (eastward.grand., d:\myProject).
```
                public class Hello {      public static void main(String[] args) {       System.out.println("Hello, globe!");    } }
```

Step half dozen: Compile and Run the Hello-World Java Program

To compile the source lawmaking "How-do-you-do.java":

Starting time a CMD Vanquish (Search ⇒ enter "cmd" ⇒ select "Command Prompt").
Set the Current Drive to the drive where y'all saved your source file "Hullo.java".
If you use bulldoze "c", skip this step.
Else if you use drive "d", enter " d: " as follow:
```
              d:              D:\xxx>            
```
Gear up the Current Working Directory to the directory that you saved your source file via the cd (Change Directory) command. For example, suppose that your source file is saved in directory "myProject".
```
              cd \myProject              D:\myProject>            
```

Issue a dir (List Directory) command to confirm that your source file is present in the current directory.

              dir              ...... 20-xxx-twenty  xx:xx PM               277                Hello.java                ......

Invoke the JDK compiler " javac " to compile the source code "Hello.java".
```
              javac Hello.java            
```
The compilation is successful if the command prompt returns. Otherwise, error letters would be shown. Correct the errors in your source file and re-compile. Check "Common JDK Installation Errors", if you encounter problem compiling your plan.

The output of the compilation is a Java class chosen "Hello.class". Issue a dir (List Directory) command again to bank check for the output.

              dir              ...... twenty-xxx-20  xx:20 PM               416                How-do-you-do.class                xx-30-xx  xx:xx PM               277 How-do-you-do.java ......

To run the program, invoke the Coffee Runtime " java ":

          java Hello          Hello, world!

Everything that tin can possibly get wrong will go wrong: Read "JDK Installation Common Errors".

Step 7: (For Avant-garde Users Only) JDK'southward Source Code

Source code for JDK is provided and kept in "<JAVA_HOME>\lib\src.zip" (or "<JAVA_HOME>\src.aught" prior to JDK 9). I strongly recommend that y'all to go through some of the source files such as "String.java", "Math.java", and "Integer.coffee", under "java\lang", to learn how experts plan.

How to Install JDK on macOS

Footstep 1: Bank check if JDK has been Pre-Installed

To check if JDK has been installed, open up a "Final" (Search "Terminal"; or Finder ⇒ Become ⇒ Utilities ⇒ Terminal) and issue this command:

          javac -version

If a JDK version number is returned (e.yard., JDK x.x.ten), then JDK has already been installed. If the JDK version is prior to 11, go on to Step ii to install the latest JDK; otherwise, proceed to "Step iii: Write a Howdy-world Coffee programme".
If message "control non establish" appears, JDK is Non installed. Proceed to the "Step two: Install JDK".
If bulletin "To open javac, you need a Java runtime" appears, select "Install" and follow the instructions to install JDK. Then, proceed to "Step 3: Write a How-do-you-do-globe Coffee program".

Step 2: Download JDK

Goto JDK (or Java SE) download site @ https://www.oracle.com/java/technologies/javase-downloads.html.
Under "Coffee SE Development Kit 17.0.{x} downloads".
Select "macOS" ⇒ Download the "x64 Installer" (e.k., "jdk-17_windows-x64_bin.exe" - about 152MB).
Under "Oracle JDK", click "JDK Download".
Download the "x64 DMG installer" (e.g, jdk-17_macos-x64_bin. dmg - nearly 168MB (I am assuming that you are using Intel processor, non ARM processor. Mac is moving to ARM processor.)

Pace 3: Install JDK/JRE

Double-click the downloaded Disk Image (DMG) file. Follow the screen instructions to install JDK/JRE.
Squirt the DMG file.

To verify your installation, open a "Terminal" and effect these commands.

                javac -version              javac 17.0.{x}                            java -version              java version "17.0.{x}" ......                            which javac              /usr/bin/javac                            which java              /usr/bin/java

Step three: Write a Howdy-World Java Programme

Create a directory called "myProject" under your "habitation" directory (Launch "Finder" ⇒ "Go" ⇒ "Habitation"; Select "File" ⇒ "New Folder" ⇒ "myProject").
In macOS/Unix, the "home" directory of the current user tin be referenced equally "~". Hence, this new directory can be referenced equally "~/myProject".
Utilize a programming text editor (such every bit Sublime Text or Atom) to input the following source lawmaking and salvage as "How-do-you-do.coffee" under the directory "~/myProject".
(If you employ macOS'southward default text editor "TextEdit" (NOT recommended), you need to open a new file ⇒ cull "Format" ⇒ "Make Plain Text" ⇒ Enter the source lawmaking ⇒ Save as "Hello.coffee".)
```
                public course Hello {       public static void main(String[] args) {       System.out.println("Hello, world from Mac!");    } }
```

Footstep 4: Compile and Run the How-do-you-do-World Java Program

To compile the source code "Hullo.java", open up a new "Terminal" ("Go" ⇒ "Utilities" ⇒ "Last") and issue these commands (equally illustrated):

                cd ~/myProject                            ls              Hello.java   ......                            javac Hello.java                               ls              Hello.grade   Hello.java   ......

To run the Hello-world, invoke the Java Runtime "java" as follows:

              java Hello              Howdy, world from Mac!

How to Install JDK (fifteen) on Ubuntu

We shall effort both the OpenJDK (free and open up-source) and the Oracle JDK (gratuitous for personal and evolution, just not free for production).

Step 0: Cheque if JDK has already been Installed

Open a Terminal and issue this control:

$          javac -version

If a JDK version number (e.one thousand., "javac ten.10.ten") appears, JDK has already been installed. You lot can skia the installation and goto Open2.

Step 1a: Install OpenJDK

[TODO]

To remove OpenJDK, result command:

$          sudo apt-get purge openjdk-\*

Step 1b: Install Oracle JDK

Goto Oracle JDK (Java SE) download site @ https://www.oracle.com/coffee/technologies/javase-downloads.html ⇒ Under "Oracle JDK", click "JDK Download" ⇒ Select "Linux x64 Compressed Archive" package (e.chiliad., "jdk-15.0.{x}-linux-x64_bin.tar.gz" - 179MB). The tarball volition be downloaded in directory "~/Downloads", by default.
Nosotros shall install JDK nether "/usr/local/java" (or Ubuntu's default JDK directory /usr/lib/jvm; or /opt/java). Outset, create a directory "coffee" under "/usr/local". Open up a Terminal and issue these commands:
```
$              cd /usr/local              $              sudo mkdir java            
```
Extract the downloaded package (Bank check your downloaded filename!)
```
$              cd /usr/local/java              $              sudo tar xzvf ~/Downloads/jdk-15.0.{x}-linux-x64_bin.tar.gz            
```
JDK shall be extracted in a folder "/usr/local/java/jdk-15.0.{10}", where {x} is the update number.

Inform the Ubuntu to use this JDK/JRE:

                $              sudo update-alternatives --install "/usr/bin/coffee" "java" "/usr/local/java/jdk-15.0.{x}/bin/java" 1               $              sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/local/java/jdk-15.0.{x}/bin/javac" ane              $              sudo update-alternatives --install "/usr/bin/jshell" "java/usr/local/java/jdk-15.0.{10}/bin/jshell" 1               $              sudo update-alternatives --prepare java /usr/local/java/jdk-xv.0.{10}/bin/java               $              sudo update-alternatives --prepare javac /usr/local/java/jdk-15.0.{x}/bin/javac              $              sudo update-alternatives --ready jshell /usr/local/coffee/jdk-15.0.{x}/bin/jshell

The to a higher place steps set upward symlinks java, javac, jshell at /usr/bin (which is in the PATH), that link to /etc/alternatives and and then to JDK bin directory.
The "alternatives" organization aims to resolve the situation where several programs fulfilling the same function (due east.thou., different version of JDKs). It sets upwardly symlinks thru /etc/alternatives to refer to the actual programs to exist used.

$              ls -ld /usr/bin/java*              lrwxrwxrwx 1 root root twenty thirty xx xx:xx /usr/bin/coffee -> /etc/alternatives/java ......              $              ls -ld /etc/alternatives/java*              lrwxrwxrwx 1 root root twenty 30 xx twenty:xx /etc/alternatives/java -> /usr/local/coffee/jdk-15.0.{x}/bin/java ......               java -> /usr/bin/coffee (thru PATH) -> /etc/alternatives/java -> /usr/local/java/jdk-fifteen.0.{x}/bin/java (bodily programme)

Alternatively, you tin include the JDK'southward bin into the PATH directly.

To verify the JDK installation, outcome these commands:

                $              javac -version              javac fifteen.0.{x}               $              coffee -version              java version "15.0.{x}" ......               $              which javac              /usr/bin/javac              $              which java              /usr/bin/java

(Don't Do this footstep - It is taken care by "alternatives" in Step 3. Proceed here to show you how to set PATH.)
Add JDK'southward binary directory ("bin") to the "PATH" by editing "/etc/profile":

$              cd /etc              $              sudo nano profile

Add together these lines at the cease of the file "/etc/profile", replace "{x}" with the actual number:

export JAVA_HOME=/usr/local/java/jdk-xv.0.{x} consign PATH=$JAVA_HOME/bin:$PATH

Rerun the configuration file by:

                $              source /etc/contour               $              repeat $JAVA_HOME              /usr/local/coffee/jdk-15.0.{x}              $              repeat $PATH              /usr/local/java/jdk-15.0.{x}/bin:......

Step 2: Compile and Run a Hello-world Java Program

File Explorer ⇒ Habitation ⇒ Create a new folder called "myProject" to keep our works.
Open up "Text Editor" (gedit). Enter the following source code and save as "Hello.java" under the "~/myProject" directory created earlier.
```
public class Hello {       public static void main(Cord[] args) {       System.out.println("Hello, world from Ubuntu!");    } }
```

To compile the Howdy-world Java program, launch a Concluding and issue these commands:

                $              cd ~/myProject               $              ls              ...... Hullo.java ......               $              javac Hi.java               $              ls              ...... Hello.class ......

Run the Hello-globe Java program:

                $              java Howdy              Hello, world from Ubuntu!

Notes: Starting from JDK eleven, you tin can compile and run the hi-world in one unmarried step via:

            $          java Hello.coffee          Hello, world from Ubuntu!

Source-Code Editors & IDEs for Java Programming

Eclipse IDE

You need to first install Eclipse. Read "How to Install Eclipse".
javaan and so proceed to write your first Java program. Read "Writing your first Java Program with Eclipse".
Eclipse allow yous to debug plan graphically. Read "Debugging program in Eclipse".

NetBeans IDE

You demand to first install NetBeans. Read "How to Install NetBeans".
You can so proceed to write your first Java plan. Read "Writing your starting time Java program with NetBeans".
NetBeans allow you to debug program graphically. Read "Debugging plan in NetBeans".

Visual Studio (VS) Lawmaking IDE

Click Hither, look for "VS Code for Java Programming"

Sublime Text (for Windows, macOS, Linux)

Click Here, look for "Sublime Text for Java Programming"

Cantlet (for Windows, macOS, Linux)

[TODO]

TextPad (for Windows only)

Click HERE, look for "TextPad for Java Programming".

NotePad++ (for Windows only)

Click Hither, look for "NotePad++ for Java Programming".

(JDK 11 New Feature) Launch Single-Source-File

From JDK 11, you can "compile and run" a single-file program in one step, without explicit compilation.

Write a "Hello.java" (see previous section).
Delete "Hi.course", if it exists.

You tin compile/run "Hello.java" in one command as follows:

                              java Hello.coffee              Hello, globe!

Notes:

This is applicable to single source-file only.
No need to utilise javac to compile the program.
It compiles in memory (without producing a .class file), and run.
This feature is introduced for beginners to learn Coffee, and for professionals to test a Java feature.
The filename and classname need not be the same.

How To Set JAVA_HOME Environment Variable

Many Java applications (such as Tomcat) require the environment variable JAVA_HOME to exist set to the JDK installed directory.

See "How to prepare JAVA_HOME for Windows" or "How to set JAVA_HOME for macOS/Linux".

Mutual Errors in installing JDK

          SYMPTOM:          Cannot compile Coffee program from the CMD vanquish (e.g., "javac Hello.java" does non piece of work!)          Error MESSAGE:          'javac' is not recognized as an internal or external control, operable program or batch file.          PROBABLE CAUSES:          The PATH environment variable, which maintains a listing of search paths for executable    programs (including "javac.exe"), does non include JDK's bin directory.          POSSIBLE SOLUTIONS:          1) Start a CMD beat (click "Outset" push ⇒ "run..." ⇒ enter "cmd") and issue a          path          command:          prompt>          path          PATH=.......    ii) Bank check if it includes your JDK'south "bin" directory. For example, suppose that your JDK is installed        in "c:\programme files\coffee\jdk-15.0.one", and then PATH should include "c:\program files\java\jdk-fifteen.0.ane\bin".       Otherwise, include JDK's bin directory in the PATH environment variable.       Read "Step 3 of How to install JDK".

          SYMPTOM:          Tin compile but cannot run Java programme from the CMD shell (eastward.g., "java Hello" does not piece of work!)          ERROR Bulletin (Post JDK one.7):          Error: Could not discover or load main class 30          Mistake Message (Pre JDK i.7):          Exception in thread "main" java.lang.NoClassDefFoundError: 30          Likely CAUSES:          1) The Coffee form (in this example, Hi.form) is Non in the current directory.    2) The CLASSPATH environs variable is set, simply does not include the current directory ".".          POSSIBLE SOLUTIONS:          1) Outcome a "dir" control to listing the contents of the current directory.        Check that it contains the Java class to be run (e.g., Howdy.class).        You lot need to compile the source program (".java") to get the class file (".grade").    ii) If the Java class is nowadays in the current directory, result a "set classpath" command       to cheque its settings:             prompt>          set classpath          CLASSPATH=.......       If you lot receive the message "Environment variable CLASSPATH not divers" and          your plan is correct, I tin can't help you hither.       Otherwise, if the CLASSPATH is defined, for beginner, I suggest that y'all remove         the CLASSPATH surround variable.          From "Control Panel"         ⇒ Organisation         ⇒ (Vista just) Advanced system settings          ⇒ Switch to "Advanced" tab          ⇒ Environs Variables          ⇒ System variables (and also User variables)          ⇒ Select variable "CLASSPATH"          ⇒ Delete (Delete from both the System variables and User variables)    three)          (For Advanced Users Only)          If CLASSPATH is not prepare, information technology is defaulted to the current directory.       However, if CLASSPATH is set, the current  directory is Not implicitly included.       You tin can include the current  directory (denoted past a single dot ".") in front of the        existing class-paths.        Read "Java Applications and Surroundings Variable" for more discussion on CLASSPATH.

          SYMPTOM:          Can compile but cannot run the Hello-globe plan (e.grand., "java Hullo" does not work!)          Fault Bulletin (Post JDK 1.7):          Error: Main method not found in form Hi.          POSSIBLE SOLUTIONS:          Check whether there is a primary() method in your programme, and the signature of your main()   as shown in the mistake message.

(Advanced) External JAR Files and Native Libraries

Notes: This section is applicable to JDK prior to JDK 9. JDK 9 introduces a new level chosen "module" on superlative of package, and "jmod" files for Coffee modules. Need to revise this section for JDK nine.

External Java API packages (such as Servlet API, MySQL Connector/J, JOGL, JUnit) are often distributed in JAR files (Java Archive - a single-file parcel of many Java classes similar to Cipher or TAR), with possibly Native Libraries (".lib" and ".dll" in Windows, or ".a" and ".so" in Linux/macOS).

External JAR Files (".jar")

If external JAR files are not properly included:

During the compilation, you will receive compilation fault "cannot find symbol" for classes belonging to the external packages.
During execution, you volition go a runtime mistake "Could non discover or load master form xxx" or "NoClassDefFoundError".

To include external JAR files, you can either:

(Prior to JDK 9) Copy all the JAR files of the external packages to the Coffee'southward Extension Directories (Not applicative from JDK nine).
- For Windows, the JDK extension directory is located at "<JAVA_HOME>\jre\lib\ext" (e.1000., "c:\Program Files\Coffee\jdk1.8.0_xx\jre\lib\ext").
- For macOS, the JDK extension directories are "/Library/Coffee/Extensions" and "/System/Library/Java/Extensions".
- For Ubuntu, the JDK extension directories are "<JAVA_HOME>/jre/lib/ext" (e.thou., "/usr/user/java/jdk1.eight.0_xx/jre/lib/ext") and "/usr/java/packages/lib/ext".
The location of JDK's extension directories is kept in Java's System Property "java.ext.dirs". You tin print its contents via System.out.println(System.getProperty("java.ext.dirs")).
You lot can also include all the JAR files in the CLASSPATH environs variable. CLASSPATH may incorporate directories (of Java classes) or JAR files (single-file archive of Java classes). If you set the CLASSPATH, you lot must also include the current directory (denoted as ".").
- For Windows, set the CLASSPATH in Control Panel ⇒ System ⇒ Avant-garde system settings ⇒ Avant-garde ⇒ Surroundings Variables ⇒ System Variables ⇒ New ⇒ In "Variable proper name", enter "CLASSPATH" ⇒ In "Variable value", enter ".;path1\30.jar;path2\yyy.jar", where the entries are separated by a semi-colon (;).
- For Linux and macOS: Edit ~/.profile or ~/.bash_profile (or /etc/profile for system-broad setting) to include the post-obit line at the cease of the file:
```
export CLASSPATH=.:path1/30.jar:path2/yyy.jar
```
  The entries are separated by colon (:).

You lot can too set the CLASSPATH in the javac/java command-line via the option -cp <paths> (or -classpath <paths>), for example,

                 javac              -cp .;path1\xxx.jar;path2\yyy.jar              ClassName.java  java              -cp .;path1\xxx.jar;path2\yyy.jar              ClassName               javac              -cp .:path1/30.jar:path2/yyy.jar              ClassName.java  java              -cp .:path1/thirty.jar:path2/yyy.jar              ClassName

External Native Libraries (".lib", ".dll", ".a", ".and then")

Some external package may provide static or shared native libraries in the form of ".lib" (Windows' static LIBrary), ".dll" (Windows' Dynamically Link Library), ".a" (Unix's static (Archive) library), or ".so" (Unix's Shared Object library).

Native Libraries are to be kept in a directory accessible via JRE's Holding "java.library.path", which normally but not necessarily includes all the directories in the PATH environment variable.

Native libraries are not involved in the compilation. Simply if they are not properly included during runtime time, you volition go a runtime mistake "java.lang.UnsatisfiedLinkError: no xxx in coffee.library.path".

To include external native libraries:

Re-create the native libraries into a arrangement library directory, e.g., c:\windows\system32 (Windows), /usr/lib or /usr/local/lib (macOS/Unix). Yous can verify that the directory is included in Java's System Belongings "java.library.path", via System.out.println(System.getProperty("coffee.library.path")).

You can also set the native library path via the java's control-line choice -Djava.library.path=30 , for example,

                java              -Djava.library.path=xxx                            ClassName

Eclipse/NetBeans

Using an IDE can greatly simplifies inclusion of external packages. Read "Eclipse How-To" or "NetBeans How-To".

Link to References & Resources