NullPointerException while trying to copy file

[Foss User]

I was trying to write a Java code to copy a file from local system to
a file system (which is also local file system). This is my code.

package in.fossist.examples;

import java.io.File;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.LocalFileSystem;
import org.apache.hadoop.fs.FileUtil;

public class FileOps
{
    public static void main(String[] args) throws IOException
    {
        FileUtil.copy(new File("a.txt"),
                      new LocalFileSystem(),
                      new Path("b.txt"),
                      false,
                      new Configuration());
    }
}

This is the error:

ubuntu:/opt/hadoop-0.19.1# bin/hadoop jar fileops-0.1.jar
in.fossist.examples.FileOps
java.lang.NullPointerException
        at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:375)
        at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:367)
        at org.apache.hadoop.fs.FileUtil.copy(FileUtil.java:286)
        at in.fossist.examples.FileOps.main(Unknown Source)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at 
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.hadoop.util.RunJar.main(RunJar.java:165)
        at org.apache.hadoop.mapred.JobShell.run(JobShell.java:54)
        at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
        at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)
        at org.apache.hadoop.mapred.JobShell.main(JobShell.java:68)

Please help me to fix this error.