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

Answer 1

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

Answer 2

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.

Answer 3

java -classpath Predit.jar your.package.name.MainClass

Answer 4

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.

Answer 5

To run jar, first u have to create

executable jar

then

java -jar xyz.jar

command will work