Exception handling help in java word counter

I have written this code, for a java word counter that takes input from single or multiple files and gives back the output for the number of words. While exception handling, I require it to give me an error message when the execution code lacks specification of files names.
For example:
javac wordcount.java should return an error message
and
javac wordcount.java names.java should return the number of words.

Here is my code:

import java.io.*;
import java.util.*;
import java.text.*;
public class wordcount extends Thread {
  String str;
  public wordcount(String s) {
    this.str = s;
  }
  public static void main(String args[]) throws Throwable {
    for (String s: args) {
      //System.out.println(s);
      new wordcount(s).start();
    }
  }
  public void run() {
    System.out.println(this.str);
    try {
      File file = new File(this.str);
      Scanner sc = new Scanner(new FileInputStream(file));
      if {
        System.out.println("file doesnt exist");
      }
      int count = 0;
      while (sc.hasNext()) {
        sc.next();
        count++;
      }
      System.out.println("File :" + this.str + "=" + count);
    } catch (Exception e) {
      System.out.println(e);
    }
  }
}