How to run a JAR file

Question

I created a JAR file like this   jar cf Predit jar       I ran this JAR file by double clicking on it  it didn t work   So I ran it from the DOS prompt like this   java -jar Predit jar   It raised  Failed to load main class  exceptions  So I extracted this JAR file   jar -xf Predit jar   and I ran the class file   java Predit   It worked well  I do not know why the JAR file did not work  Please tell me the steps to run the JAR file

User · Answer

java -classpath Predit jar your package name MainClass

User · Answer

You need to specify a Main-Class in the jar file manifest   Oracle s tutorial contains a complete demonstration  but here s another one from scratch  You need two files   Test java   public class Test       public static void main String   args                System out println  Hello world              manifest mf   Manifest-version  1 0 Main-Class  Test   Note that the text file must end with a new line or carriage return  The last line will not be parsed properly if it does not end with a new line or carriage return   Then run   javac Test java jar cfm test jar manifest mf Test class java -jar test jar   Output   Hello world

User · Answer

Eclipse Runnable JAR File  Create a Java Project     RunnableJAR   If any jar files are used then add them to project build path  Select the class having main   while creating Runnable Jar file     Main Class  public class RunnableMainClass       public static void main String   args  throws InterruptedException           System out println  Name     args 0            System out println   ID      args 1              Run Jar file using java program  cmd  by supplying arguments and get the output and display in eclipse console   public class RunJar        static StringBuilder sb   new StringBuilder        public static void main String   args  throws IOException           String jarfile    D   JarLocation  myRunnable jar           String name    Yash           String id    777            try      jarname arguments has to be saperated by spaces             Process process   Runtime getRuntime   exec  cmd exe start  C java -jar   jarfile     name     id                          exec  cmd exe  C start dir java -jar   jarfile     name     id   dir                BufferedReader br   new BufferedReader new InputStreamReader process getInputStream                   String line   null              while   line   br readLine       null                   sb append line  append   n                              System out println  Console OUTPUT    n  sb toString                 process destroy             catch  Exception e               System err println e getMessage                        In Eclipse to find Short cuts   Help   Help Contents   Java development user guide   References   Menus and Actions

User · Answer

A very simple approach to create  class   jar file   Executing the jar file  No need to worry too much about manifest file  Make it simple and elgant   Java sample Hello World Program  public class HelloWorld       public static void main String   args            System out println  Hello World              Compiling the class file  javac HelloWorld java   Creating the jar file  jar cvfe HelloWorld jar HelloWorld HelloWorld class   or  jar cvfe HelloWorld jar HelloWorld   class   Running the jar file   java -jar HelloWorld jar   Or  java -cp HelloWorld jar HelloWorld

User · Answer

I have this folder structure      D  JavaProjects OlivePressApp com lynda olivepress Main class   D  JavaProjects OlivePressApp com lynda olivepress press OlivePress class   D  JavaProjects OlivePressApp com lynda olivepress olives Kalamata class   D  JavaProjects OlivePressApp com lynda olivepress olives Ligurian class   D  JavaProjects OlivePressApp com lynda olivepress olives Olive class   Main class is in package com lynda olivepress  There are two other packages      com lynda olivepress press      com lynda olivepress olive   1  Create a file named  Manifest txt  with Two Lines  First with Main-Class and a Second Empty Line   Main-Class  com lynda olivepress Main   D  JavaProjects OlivePressApp  Manifest txt  2  Create JAR with Manifest and Main-Class Entry Point  D  JavaProjects OlivePressApp jar cfm OlivePressApp jar Manifest txt com lynda olivepress Main class com lynda olivepress    3  Run JAR  java -jar OlivePressApp jar  Note  com lynda olivepress   means including the other two packages mentioned above  before point 1

User · Answer

You have to add a manifest to the jar  which tells the java runtime what the main class is  Create a file  Manifest mf  with the following content   Manifest-Version  1 0 Main-Class  your programs MainClass   Change  your programs MainClass  to your actual main class  Now put the file into the Jar-file  in a subfolder named  META-INF   You can use any ZIP-utility for that

User · Answer

Java  class Hello     public static void main String    args       System out println  Hello Shahid             manifest mf  Manifest-version  1 0 Main-Class  Hello   On command Line     jar cfm HelloMss jar  manifest mf Hello class    java -jar HelloMss jar   Output    Hello Shahid

User · Answer

If you don t want to deal with those details  you can also use the export jar assistants from Eclipse or NetBeans

User · Answer

Before run the jar check Main-Class  classname is available or not in MANIFEST MF file  MANIFEST MF is present in jar   java -jar filename jar

User · Answer

If you don t want to create a manifest just to run the jar file  you can reference the main-class directly from the command line when you run the jar file   java -jar Predit jar -classpath your package name Test   This sets the which main-class to run in the jar file

User · Answer

To run jar  first u have to create      executable jar   then      java -jar xyz jar    command will work

[java] How to run a JAR file

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