Code in main does not require catch, but code in constructor does

Question

this is the original program, its all in main. i took all the code out of main and put it in a constructor to make it more usable, and started making the necessary adjustments. i eventually got it to work but i had to catch exceptions EVERYWHERE. why does this code not require so many exceptions when the code is in main?
import java.io.BufferedInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
public class MainClass {
  public static void main(String args[]) throws Exception {
    URL u = new URL("");
    URLConnection uc = u.openConnection();
    String contentType = uc.getContentType();
    int contentLength = uc.getContentLength();
     // ||
    if (contentLength == -1) {
      throw new IOException("Error: No File Found.");
    InputStream raw = uc.getInputStream();
    InputStream in = new BufferedInputStream(raw);
    byte[] data = new byte[contentLength];
    int bytesRead = 0;
    int offset = 0;
    while (offset < contentLength) {
      bytesRead = in.read(data, offset, data.length - offset);
      if (bytesRead == -1)
        break;
      offset += bytesRead;
    in.close();
    if (offset != contentLength) {
      throw new IOException("Only read " + offset + " bytes; Expected " + contentLength + " bytes");
     String dirText = "text";
     String dirTarget = "target";
     String filename = u.getFile().substring(u.getFile().lastIndexOf('/') + 1);
     String dirAndFile;
     // determine weather the file is a target or is to be parsed for more files
     if(contentType.startsWith("text/")) {
          dirAndFile = dirText + "\\" + filename;
     else {
          dirAndFile = dirTarget + "\\" + filename;
    FileOutputStream out = new FileOutputStream(dirAndFile);
    out.write(data);
    out.flush();
    out.close();
}Edited by: chopficaro on May 1, 2010 8:15 AM

Answer 1

ok but still, why do i not have to catch all these exceptions when the code is in main rather than a constructor? heres the code after i put it in the constructor:
import java.io.BufferedInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.net.MalformedURLException;
public class MainClass {
     public static void main(String args[]) throws Exception
          MainClass mc = new MainClass("http://www.google.com/intl/en_ALL/images/logo.gif");
     MainClass(String addr)
          URL u = null;
          try
               u = new URL(addr);
          catch (MalformedURLException e)
               // Print out the exception that occurred
               System.out.println("Invalid URL "+addr+": "+e.getMessage());
          URLConnection uc = null;
          try
               uc = u.openConnection();
          catch (IOException e)
               // Print out the exception that occurred
               System.out.println("Unable to create "+addr+": "+e.getMessage());
          String contentType = uc.getContentType();
          int contentLength = uc.getContentLength();
          if (contentLength == -1)
               System.out.println("no file");//throw new IOException("Error: No File Found.");
          InputStream raw=null;
          InputStream in=null;
          try
               raw = uc.getInputStream();
               in = new BufferedInputStream(raw);
          catch (IOException e)
          // Print out the exception that occurred
          System.out.println("bad input stream "+e.getMessage());
          byte[] data = new byte[contentLength];
          int bytesRead = 0;
          int offset = 0;
          while (offset < contentLength)
               try
                    bytesRead = in.read(data, offset, data.length - offset);
               catch (IOException e)
                    // Print out the exception that occurred
                    System.out.println(e.getMessage());
               if (bytesRead == -1)
               break;
               offset += bytesRead;
          try
               in.close();
          catch (IOException e)
               // Print out the exception that occurred
               System.out.println(e.getMessage());
          if (offset != contentLength)
               System.out.println("didnt read enough bytes"); //throw new IOException("Only read " + offset + " bytes; Expected " + contentLength + " bytes");
          String dirText = "text";
          String dirTarget = "target";
          try
               String filename = u.getFile().substring(u.getFile().lastIndexOf('/') + 1);
               String dirAndFile;
               // determine weather the file is a target or is to be parsed for more files
               if(contentType.startsWith("text/"))
                    dirAndFile = dirText + "\\" + filename;
               else
                    dirAndFile = dirTarget + "\\" + filename;
               FileOutputStream out = new FileOutputStream(dirAndFile);
               out.write(data);
               out.flush();
               out.close();
          catch (IOException e)
               // Print out the exception that occurred
               System.out.println(e.getMessage());
}