# Hello World

Calculations start from a special `StartPoint` class. That class contains main method (`public void main()`):

```java
import java.io.IOException;
import org.pcj.*;

public class HelloWorld implements StartPoint {

    public static void main(String[] args) throws IOException {
    String nodesFile  = "nodes.txt";
    PCJ.executionBuilder (PcjExample.class)
                .addNodes(new File("nodes.txt"))
                .start();
    }
    }

    @Override
    public void main() throws Throwable {
                System.out.println("Hello World from PCJ Thread " + PCJ.myId()
                                   + " out of " + PCJ.threadCount() );
            }
}
```

The compilation and execution requires *PCJ-5.0.9.jar* in the path:

`javac -cp .:PCJ.jar HelloWorld.java java -cp .:PCJ-5.0.9.jar HelloWorld`

The expected output is presented below:

`wrz 23, 2016 2:00:22 AM org.pcj.internal.InternalPCJ start INFO: PCJ version 5.0.0.SNAPSHOT-a728f5f built on 2016-09-13 00:58:48.180 CEST. wrz 23, 2016 2:00:22 AM org.pcj.internal.InternalPCJ start INFO: Starting HelloWorld with 4 threads (on 1 node)... Hello World from PCJ Thread 2 out of 4 Hello World from PCJ Thread 0 out of 4 Hello World from PCJ Thread 1 out of 4 Hello World from PCJ Thread 3 out of 4 wrz 23, 2016 2:00:22 AM org.pcj.internal.InternalPCJ start INFO: Completed HelloWorld with 4 threads (on 1 node) after 0h 0m 0s. BUILD SUCCESSFUL (total time: 0 seconds)`


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